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Editorial

Hippocrates Said It First!

Hippocrates, the most important physician in antiquity, explained in his work "Treatise on Airs, Waters and Places" that man depends on the forces of nature. The "health" of the environment influences human health. Hundreds of years later, this Hippocratic approach remains absolutely valid.

The big difference from the era in which the father of clinical observation lived is the change in the environment and the lifestyles propitiated by human intelligence.

In a context of globalisation of markets and, therefore, of the logic initiated by the Industrial Revolution, Planet Earth has undergone a series of alterations that are apparent on a global as well as local level. The greenhouse effect, climatic change, the hole in the ozone layer, acid rain, desertification, loss of biological diversity and genetic resources, deterioration of many urban environments, appearance of new pathologies associated with our lifestyles… this environment affects human health. Many diseases have been eradicated, but new ones appear which are linked to a society that produces wellbeing while generating risks, many of which are associated with health.

In this issue of the magazine Medi Ambient. Tecnologia i Cultura, we take on an oceanic subject: health and environment. Our goal is to present a panoramic view of up-to-the-minute, key aspects in a field -the influence of the environment on human health- that currently moves -and will continue to move in the coming years- many medical and scientific resources.
The scientific journalist and chemist Xavier Duran argues for the need for more research in order to establish with a maximum amount of certainty the effects of environmental changes on human health. He also delves into the need to have economic indicators include the damage caused by certain products or activities in order to have the price come closer to the real cost to society.

Rosa Girbau and Catalina Salas, professors at the Nursing College of the University of Barcelona (Escola Universitària d'Infermeria de la Universitat de Barcelona), explain why the condition of the environment is a key factor in individual and collective wellbeing.

Nutrition experts Abel Mariné and Carme Vidal, researchers at the University of Barcelona, analyse the influence of the environment on food and health. They send us a message of calm in regard to the safety of the food we eat.

The physician Jordi Sunyer, researcher at the Municipal Institute of Medical Research (Institut Municipal d'Investigacions Mèdiques or IMIM), explains how the quality of the air affects our bodies. In another article, Jordi Sunyer, together with Manolis Kogevinas and Josep Maria Antó from the IMIM, set forth the latest research related to health in regard to water pollution, industrial waste, dioxins, electromagnetic fields and mobile phones.

The interview is with Alfons Calera, an expert in occupational health. Finally, there is the regular contribution by the lawyer Ignasi Doñate, who explains European regulations on protecting people and the environment from hazardous substances.
All these articles make clear just how right the wise physician Hippocrates was.

Lluís Reales
Editor of Medi Ambient. Tecnologia i Cultura

Health and the environment: from ambiguity to economic accountability
Xavier Duran.
Chemist and scientific journalist.

Despite the fact that some doubts still remain, there is increasing evidence that environmental problems have a negative impact on health. The global change that the planet is experiencing may exacerbate these problems, especially in poorer countries. In order to offset this, the effects on health need to be made economically accountable and attempts made to reduce the inequalities that increase the risks in certain areas and social classes.

One of the characters in "Hard Times" (1854), the wealthy businessman Mr. Bounderby, speaks highly of the fumes that cloud the air of the industrial town of Coketown: "That's meat and drink to us. It's the healthiest thing in the world in all respects, and particularly for the lungs. If you are one of those who want us to consume it, I differ from you. We are not going to wear the bottoms of our boilers out any faster than we wear 'em out now, for all the humbugging sentiment in Great Britain and Ireland". In this novel, Charles Dickens portrays industrial society, with its subsequent cost in social and environmental terms and inequality, in a truly masterly way. However, in a society that appeared to produce so much wealth and did well for the interests of Mr.

Bounderby, and more than likely many other people as well, what was the point in worrying about all that smoke? And even though it was so strongly affecting the working class neighbourhoods (sic) "in the innermost fortifications of that ugly citadel, where Nature was as strongly bricked out as killing airs and gases were bricked in (…), in the last close nook of this great exhausted receiver, where the chimneys, for want of air to make a draught, were built in an immense variety of stunted and crooked shapes?."1

The smoke produced by the technological and economic revolution undoubtedly caused many health problems, yet the cause of these problems had been around for some time. In 1775, the English surgeon Percival Pott noted an unusually high rate of cancer of the scrotum amongst chimney sweeps. In addition to certain work-related diseases such as this, it is likely that inadequate hygiene conditions and over-crowding, together with the use of large quantities of coal, produced an increase in the number of diseases and deaths, and that these misfortunes affected particularly the poorer social classes. In 1845, Friedrich Engels, in "The conditions of the working class in England", produced some epidemiological data according to which the mortality rate in the poorer areas of the city of Manchester were twice that of the more well-off areas. Life expectancy in the industrial centres in 1840 was 25 for the workers and 55 for the upper classes.

It would seem to be undeniable that the obvious improvements in the living conditions of the majority of people have been accompanied by inadequacies that have also contributed to the emergence or expansion of health and sanitation problems. As development has provided new tools to prevent or remedy disease, man has found himself in a social context where new risks have appeared and where the aforementioned new tools were not accessible to everybody. Instead of it increasing, particular social groups have even found their well-being to have decreased in the name of so-called progress.

Nevertheless, when it comes to establishing the consequences of environmental degradation on health or, to express it in a way that does not imply negative judgement, of the changes that socio-economic activities have introduced in the environment (together with the changes that the planet naturally undergoes), one runs up against the problems of ambiguity. Health problems in the genetic era would appear to be attributed to specific causes that can be precisely located. On the other hand, when it comes to health problems resulting from environmental conditions, this certainty is disconcerting or at least it opens the way for many difficulties in establishing the causes and consequences in a conclusive way. To start with, environmental conditions already amount to a wide range of elements from atmospheric and noise pollution to the emergence of a detrimental socio-economic setting. It therefore boils down to a very large number of possible causes that can be mutually stimulated or offset. This makes it difficult to come to any ultimate conclusion, which is what many people appear to be demanding, including, and what is even more serious, many policy makers who have to find the means to apply safeguards.

Such levels of certainty are not demanded in other areas. Many economic measures are applied without anybody having established that they have indisputably found the cause of either the problem that is to be resolved or the results that these actions will bring about. If politicians were to ask economists for the type of conclusive data that they are demanding from climatologists and ecologists, few decisions would be made in this field and it is more than likely that the state budget of most countries would still be at the level of several years ago. One cannot expect to achieve absolute certainty in the field of environmental health, as in many others, and for this reason clear indications or significant evidence should be sufficient for measures to be undertaken.

While increasing amounts of data on the effects of pollution on health have become available, it is difficult to verify these effects due to the wide variety of factors that are involved. When it comes to analysing the effects of a particular issue or thing under study, for example, the concentration of certain pollutants, factors such as predisposition, lifestyle habits, socio-economic status and other determining factors of each particular individual need to be taken into account. This in fact is done in all epidemiological studies although in many other cases it is much easier to separate the different factors.

Furthermore, different large-scale studies appear to link pollutants with the consequences for health and the increase in mortality. In the so-called Six City Study by the Harvard School of Public Health in Boston, data on mortality rates and pollution levels were compared for six cities in North America, with data on more than 8,000 adults being gathered over a period of 16 years. The results showed that the risk of dying young for people living in the most polluted city (Steubenville, Ohio) was 26% higher than that of the inhabitants of the city with the cleanest air (Portage, Washington).2 Criticism from certain sources compelled the data to be reanalysed from the point of view of a wide range of factors, such as education, income level, ethnic grouping, access to health care, and others. The inclusion of new factors by the Health Effects Institute, an independent organisation made up of both industrial and governmental groups, made no change to the results, which warned of the risk of particles smaller than 2.5 micrometers in diameter or PM2.5. Other studies would also appear to confirm that particles smaller than 10 micrometers in diameter (PM10) increase the risk of death from all causes, and especially from cardiovascular or respiratory diseases.3

Other studies link atmospheric pollution with infant and adult mortality4 and different types of disease. While new studies are required in many cases to confirm the hypotheses, sufficient indications already probably exist to enable certain relationships to be established and that show the need for measures to be taken. However, all of this depends, as is mentioned below, on the balance that is struck between the benefits and detrimental effects of these measures.

The effects of global change

On the other hand, if the relationship between environmental problems and health really does exist (the fact that it does exist would appear to be undeniable so it is more a question of what relationship and to what degree), will the situation get worse with the process of global change? Once again, one comes up against uncertainty. Even though the latest reports by the IPCC (International Panel on Climate Change) do not leave much room for doubt concerning global change, some of its consequences and the responsibility of human activities in the process, political, economic and industrial sectors do not appear to be inclined to accept the idea and, at all events, they resist taking any measures to mitigate it due, they say, to the economic cost that this would lead to. The cost-benefit balance, which is discussed further on, emerges yet again.

The expression 'global change' means that the effects go way beyond a mere increase in the average temperature of the planet. These changes will have a great effect on the complex workings of the atmosphere and the ecosystems on Earth and will lead to socio-economic and even geopolitical effects at the same time.

In what way can they affect health? Yet again, one comes up against a multiple variety of factors. The effects in each zone will not differ merely because of diverse climatic variations but because it will be necessary to consider the outset from the socio-economic, demographic and environmental points of view as well. One example, taken from some studies carried out in Germany and United States, is the extreme temperatures that have led to a slight increase in the number of deaths in summertime over the last few years although this increase has been more significant in certain places and in certain years. The reasons may be greater access to air-conditioned buildings or a reduction in the number of certain cardiovascular risk factors that increase people's susceptibility to heat waves. This will obviously not be valid, however, for all social classes in these places or for the majority of the inhabitants in other countries who will be more vulnerable to this increase in temperature.5

Some of the possible effects of global change include a decrease in air quality in urban areas with pollution problems, changes in the spatial and seasonal distribution of the vectors of certain infectious diseases, variations in the marine environment which increase the risk of toxicity from fish and shellfish consumption, and a decrease in food availability, which would enhance the problems of nutrition in different countries with a low level of socio-economic development.6

It is a complex matter to establish the consequences of all of these possible consequences because it is still not known precisely what the effects are and to what degree climatic change will take place in particular regions. Furthermore, the possible health consequences, even assuming certain climatic variations, are also a source of debate. A report by the US National Academies of Science National Research Council (NRC), published in April 2001, stated that there is very little sound scientific evidence to support the conclusions on the negative impact of climatic change on health. The report declared that the relationship between climate, human behaviour and infectious diseases is so complex that it makes any form of prediction very difficult.

The NRC committee considers that many predictions have been based on short term climatic variations without taking into account other factors that may have had an influence, such as changes in public health interventions and human geography. The differences between regions subjected to very similar conditions is very clear, one example being the outbreaks of dengue on either side of the border between United States and Mexico. Between 1980 and 1996 there were 50,000 confirmed cases in the three Mexican states that border on the Río Grande and less than one hundred in neighbouring regions just north of the river in Texas over the same period. This was due to the fact that most of the inhabitants in Texas spend more time at home where they have air conditioning and blinds on the windows. This means that there were fewer possibilities for them to get bitten by mosquitoes.

According to those who point to the sanitation risks of global change, the NRC overlooks the fact that certain changes have already been detected in the distribution of the vectors of certain diseases (mosquitoes have spread to higher areas of Papua-New Guinea, Rwanda and areas of Central and South America where there was previously no malaria) and, on the other hand, it presents a view that focuses mainly on the United States, where sanitation measures exist that are beyond the reach of developing countries.7

Some studies point out that even Nordic countries have been affected. The fact that spring has been brought forward, together with a milder climate in general, has led to an increase in encephalitis which is transmitted by a certain type of parasite. Other possible factors include a population increase in endemic areas and an increase in the number of household pets.8 Once again, however, these are countries with health and sanitation structures that enable this problem to be dealt with.

In fact, the species of mosquito that carry the micro-organisms that produce malaria and dengue have been detected at higher altitudes due to the fact that the higher temperatures enable them to adapt to places where they cannot normally live (the mosquito that transmits dengue has been observed at an altitude of 2,200 metres in Colombia). Many such countries do not have sanitation and public health service structures that permit rapid action if some initial cases are detected and the way of life and the needs of the inhabitants expose them even more to infection. These infectious diseases, malnutrition and heat waves can have much more serious effects in poorer countries.9 If sufficient attention is paid to the uncertainties, climatic change may not notably lead to an increase in the outbreak of these diseases in certain places. However, the combination of climatic change and deficient sanitation and social structures most definitely will.

There are also climatic phenomena that are independent of human action that have an influence on certain diseases. One case is the ENSO (El Niño-Southern Oscillation), an abnormally warm ocean current in the Western Pacific that can cause highly diverse effects including torrential rains and drought and affect food availability in areas that are thousands of kilometres apart. The ENSO appears to have some kind of relationship with cholera epidemics in Bangladesh and research into this could enable preventive measures to be taken inside the country itself.10

Lastly, mention should also be made of some negative effects (even though they may well be temporary) of so-called globalisation and the exportation of Western ways of life to societies that have maintained very different habits. For example, a fat and carbohydrate-rich diet rich is more than likely the cause of the increase in diabetes in countries like Nauru,11 where the metabolism of most people is adapted to food availability and climate. Another example is the appearance of cases of anorexia and bulimia in Fiji a few years after the arrival of television in these Pacific islands. According to Anne Becker, an anthropologist at the Harvard Medical School, 74% of Fijian girls thought they were too big or fat in 1998, 38 months after the arrival of TV and series like "Melrose Place" or "Xena: Warrior Princess".12 Other factors may have an influence on the appearance of these diseases but it is quite likely that the importation of fashion trends from the West has been largely responsible for this.

More than just the exportation of habits, globalisation is a complex and probably unstoppable process that provides benefits on the one hand but also generates risks and inequality on the other. The fact that markets become globalised but not regulations and controls may end up exacerbating certain problems, both in the developing and developed countries. On the one hand, there is a lack of stricter controls over the obtaining and processing of food products in developing countries (the use of particular pesticides, for example). On the other, it is not rationally justifiable that substances prohibited in developed countries continue to be used in the developing countries.

Only in certain cases can there be sufficiently convincing reasons and then with the proviso that these are periods of transition. One example is the use of DDT. One of the latest pieces of research on the effects DDT has on health points out that the number of premature births in the United States between 1959 and 1966 was linked to concentrations of DDE (a product resulting from the breakdown of DDT) in the mothers' blood. The research workers stressed that premature birth is one of the factors that contribute to the risk of infant mortality.13 However, in countries where malaria is an important cause of death, especially in children under the age of 5, the use of DDT to eliminate mosquitoes that transmit the malaria-causing micro-organism can provide more benefits than harm, as long as such measures are not viewed as a permanent solution and alternative forms of protection are searched for.

Economic accountability

Establishing the real risk of increase of certain diseases is important for deciding whether measures are to be taken and, if so, which ones. When looking for certainty, however, one should remember the words of Disraeli: "People's health is the foundation on which their well-being and strength are built". Increasing the health standards, therefore, does not just mean reducing the pain and suffering of a few people or improving the statistics for life expectancy. Health is an essential element that conditions both people's happiness and their ability to progress and increase their wealth and standard of living. In these terms, health improvement cannot be seen as a cost but as the best investment there is.

Likewise, when it comes to calculating the relationship between the cost and return of these investments, highly different and even startling interpretations can be made that depend not just on the credibility of the predictions but also the concept itself of the meaning of well-being and economic growth.

A book was published in 1997 on the economic costs of certain unhealthy habits, such as smoking and drinking alcohol, and of traffic accidents.14 The research on which the bulk of the book was based had been financially sponsored by Philip Morris, which, according to the co-ordinator of the book, "had naturally given the authors free rein to express their opinions".15 In the introduction, the co-ordinator, Francisco-Javier Braña, from the Universidad Complutense in Madrid, claimed that the differences of absenteeism between smokers and non-smokers were very small, according to studies carried out in the United States, and, furthermore, that there was no proof or studies to support the figures that have been given on the impact of tobacco on passive smokers. At all events, the conclusion of the research was that taxes on tobacco were much higher than the potentially harmful effects caused by tobacco.

As is well known, the large tobacco companies have denied for a long time that smoking is clearly related to particular types of disease or a decrease in life expectancy. It would appear that they have later changed tack, although their assessment had recourse more to bad taste that to serious economic research. A report, commissioned by Philip Morris and drafted by the Arthur D. Little firm of consultants, appeared in July 2001 with an assessment of the indirect positive effects of tobacco smoking in the Czech Republic. The conclusions were that the country made a saving of 1,227 dollars (around 1,400 euros) every time that a smoker died. In overall numbers, the Czech state would have saved around 5,800 million crowns (17.4 million euros) in 1998 from the death of smokers, as a result of the fact that it would no longer have to account for certain expenses. The balance was calculated by using figures of the interest on tobacco taxes plus savings in housing for the elderly, retirement pensions and other social and health care costs in general.

What was just another joke on the witty British comedy series "Yes, minister", with a practically identical line of argument to this, was now disguised as scientific study. The scandal forced Philip Morris to apologise and cancel similar studies in other East European countries,16 as well as recognising that "no-one benefits from the very real and serious diseases caused by tobacco".17

It is surprising, for one thing, that the tobacco company was so quick to present arguments denying the negative influence of tobacco in shortening people's lives and to consider the savings when enough people die before reaching the age when they deserve to receive a retirement pension. It is either a question of 'tobacco does not kill and the Czech State does not make any savings' or 'tobacco does kill and we are faced with a serious public health problem'.

On the other hand, however, it is also surprising to see how very little value is attached to human life and people's health. Using data that were probably very similar, yet with a completely different ethical slant, another study (this time a real scientific research project) came to different conclusions. Research workers at the Erasmus University in Rotterdam (Netherlands) calculated that if an important percentage of the people stopped smoking, then savings would be made in the short term whereas in the long term, it would mean an increase in the costs of health care, i.e. more people would live to an age when the costs shoot up.18 However, the researchers ended by emphasising the fact that if smoking is a high risk to health, then the aim of policies concerning this habit should be clear and simple, i.e. people should be discouraged from smoking because society has decided to invest money in adding years onto life and health onto years.

This just goes to show that any economic analysis of health cannot deviate from the objectives that are sought after. In terms of savings alone, this would lead to tobacco being promoted as a way of reducing expenditure on retirement and health care for the elderly. However, if good health and the increase in life expectancy are considered an asset, then they need to be accounted for in economic terms one way or another. If not, any calculations that are made will be biased. Furthermore, there are costs that would be evaluated quite differently according to the data provided - if one takes into account whether tobacco and pollution increase respiratory or cardiovascular problems or not. There are even technical devices for reducing the impact of uncertainty in these studies.19

These evaluations are also conditioned, however, because the benefits may occur in the medium or long term whereas policy makers are more interested in immediate effects on the economy and those that have a very tangible economic value. Moreover, when it comes to talking about money, the basic idea is that "all profit can be potentially evaluated in monetary terms".20
Certain environmental problems can also have different positive and negative effects. The depletion of the ozone layer enhances the effect of ultraviolet radiation, which affects the immune system as well as causing more skin cancer.21 While this can lead to higher vulnerability to infectious diseases, it can also lead to a decrease in autoimmune diseases such as diabetes.22

In other cases, environmental measures devised to deal with a particular problem can provide additional health benefits. This is the case of the reduction in greenhouse gas emissions as a way of dealing with climatic change. As well as reducing the effects of this change on health, it can also lead to benefits in the short term by reducing respiratory and cardiovascular problems. An American research team pointed out these benefits over the last two decades in Mexico City, New York city, Santiago de Chile and São Paulo that have a joint population of 45 million people.23 Their results show that a reduction in emissions until the year 2020 and in these cities alone would prevent 64,000 premature deaths, 65,000 cases of chronic bronchitis and 37 million working days lost due to incapacity for work or limited working activity. They emphasised that the calculations are conservative as many other pollutants and effects, which cannot be precisely quantified with current knowledge, are not included. Another study, quoted by the authors, points to the fact that a reduction of the emissions from coal-burning power stations in the United States would prevent 18,700 deaths every year and lead to a saving of 3 million lost working days and 16 million days lost through limited working activity.24

Nevertheless, the effects on health would not appear to modify the accountability of certain activities. The joy with which an increase in car sales is greeted and the pessimism that seems to accompany a decline shows the importance given to a sector that in effect does have a large impact on Gross National Product, both in terms of direct (the car industry and maintenance) and indirect profits (infrastructure, tourism, entertainment, etc.). These benefits would need to be at least made more precise with the negative effects on health, from accidents to the diseases and deaths connected with atmospheric and noise pollution, without mentioning the costs of congestion and time wasted. In Mexico City, for example, seventy-five percent of all pollution comes from motor vehicles. Many large cities in Asia also have serious problems due to the large increase in the number of vehicles.

There is probably more documentary evidence covering the effects of lead pollution than most others. Although there are other possible sources of this metal, most of the lead absorbed into the bodies of children comes from petrol that contains lead as an additive.25 The increase in the use of lead-free petrol has led to a significant decrease in the concentrations of this metal in people's blood.26

Lead causes various problems in neurological development. A relationship has been observed between levels of lead and lower IQ and learning problems. Moreover, it may be practically impossible or highly difficult to correct the effects of exposure during infancy. At least one experiment with a drug to eliminate lead from the body showed that children did not undergo any improvement in IQ.27

These effects of pollution (lead and other substances) should logically either be included as a negative effect of the increase in the number of cars or internalised in the cost of fuel. On the other hand, it is curious how often the opposite occurs. For example, the lower price of diesel petrol leads to an increase in the number of vehicles with diesel engines, despite the negative impact that this type of fuel has on health, due to both carcinogenic effects (probably much less than tobacco) and respiratory and cardiovascular problems.28 These costs should be incorporated in the price of diesel petrol.

Another example is that of the research carried out by Jordi Sunyer and his team at IMIM (Barcelona Municipal Institute of Medical Research).29 From a study of 95 healthy children born in Flix (Ribera d'Ebre) between 1997 and 1999, they observed that the ones who were breast-fed had concentrations of hexachlorobenzene (an organo-chlorate) that were three times higher than the others, but, at the same time, their level of neurobehavioral development was also higher. This was due to the fact that the nutrients in their mothers' milk provided benefits despite the cost of ingesting organo-chlorates as well. The study showed that children in the area, where the Ercros Industrial factory (formerly Erkimia) is located, have a lower than average level of neurobehavioral development compared to Catalonia as a whole. Studies are needed to find out if this is due to organo-chlorate levels or other causes (socio-economic level, other types of environmental exposure). If it can be shown that there is a relationship with the industrial activity, aside from taking action concerning the organo-chlorate levels, an economic cost assessment would need to be introduced in order to consider not just the possible benefits of factory installation location (creation of on-site jobs, indirect income).

The subject of exposure to pollutants such as lead and their effects leads us to the last point to be dealt with, i.e. socio-economic inequalities. Lead causes a lot more harm in low-income areas. As ever, it is necessary to consider other possible factors that may have an effect on the result although there does appear to be sufficient proof by now that it is the presence of this metal that causes a large number of these problems. This would suggest that environmental problems have a much more negative impact on the lower social classes.

The relationship between purchasing power and health and life expectancy has been extensively researched and differences occur both between countries and within the different regions of a particular country. 30 People with lower incomes are more exposed to infectious agents and the effects of pollution and they have less health care assistance and access to preventive measures and exploration. Moreover, certain habits or problems considered to be risk factors (smoking, alcoholism, obesity, under-nourishment, etc.) are also more widespread in these groups. The WHO, in its annual report in 1998, declared that poverty is the major cause of disease and premature death in the world.

Low socio-economic levels are connected with the incidence of environmental problems because cheaper housing is available in industrial areas and areas with other characteristics that expose them more to these problems. Exposure to pollution or inadequate hygiene conditions thus appears to be an inevitable fact for the levels of society that cannot afford to spend more on living somewhere else.

These groups however also face many other problems when it comes to taking measures to reduce exposure to risk factors. The increase in respiratory problems in the developing world would decrease substantially if families used stoves and fuel that were less polluting. It is not so much a question of pollution in the outside air but more of inside people's homes, which are often badly ventilated. One study carried out of 55 families in Kenya showed that exposure to particles of PM10 was, in extreme cases, up to 100 times higher than the levels recommended by the EPA, the US environment agency. The transfer of technology to replace stoves and basically for people to stop using coal or wood would have a positive effect on 2,000 million people around the world.31 In the case of India, where 80% of all homes use these types of fuel, interior domestic pollution causes half a million infant deaths per year. Seventy-five percent of exposure to pollutant particles occurs in rural areas of developing countries and this translates into 3 million deaths every year around the world,32 yet these people lack the resources to put alternatives into practice or to live in better-ventilated houses.

Conclusions

Bringing about the reduction in the damage that environmental changes cause to health means, in the first place, more research in order to have certain knowledge of the damage, and also action, even though there is only a certain amount of proof available or signs that are clear enough. It also means including the damage caused by certain products and activities in economic indicators in order for the cost to be brought nearer to what the real cost means for society. Lastly, the inequalities preventing most of humanity from having access to these benefits need to be reduced, given that many people cannot provide themselves with these from other sources or change their habits with the means at their disposal.

All of this is complex enough, although it is possible, at least partially. I began with a quote from Dickens' "Hard Times" and finish off with a reference to "Faust" by Goethe. One of the goals of the main character is the construction of a sea wall on the coast to transform the area into a garden "like Eden". The difficulties in carrying out the gigantic construction and the unperceived consequences are, for some, a warning by Goethe of the problems created by the Industrial Revolution and excessive economic growth. Faust believes that all of the obstacles can be overcome by applying man's knowledge and the current level of technological achievement, which turns out to be untrue.

Man has often believed that his level of technological and economic development lets him go on with extremely ambitious projects but when it comes down to attaining other goals, such as improving people's health and reducing mortality around the world, it is as if too many voices begin to clamour that this is a utopian operation that would either be unsuccessful or prohibitively expensive. This is perhaps a good time to set Faust's idea in motion, where almost everything is seen to be possible, and to try and make headway, no matter how little, in projects that are probably a lot more necessary than great engineering works. We should also not forget that while our actions can have a short-term positive or negative impact, the generations that come after ours' and the life of the species see the life span of each individual as being insignificant. As Hans C. Binswanger and Kirk R. Smith say in an article on Goethe's "Faust",33 in reference to an expression by Paracelsus (the dose makes the poison), "reducing dose rates sufficiently to protect individuals may not necessarily protect society indefinitely".

References

1 --C. Dickens: "Hard Times"
2 --Dockery, D.W. et al, The New England Journal of Medicine, 1993, 329: 1753-59
3 --Samet, J.M. et al: The New England Journal of Medicine, 2000, 343: 1742-49
4 --Pollution may be responsible for 9% of infant deaths in the United States, according to a study by the University of Basel (Switzerland) and the Harvard School of Public Health, presented at the annual meeting of the American Thoracic Society in San Francisco on 23 May 2001.
5 --McMichael, T. (2001): "Human frontiers, environments and disease. past patterns, uncertain futures", Cambridge University Press, p. 259
6 --"Technical Summary: Impacts, Adaptation and Vulnerability", www.ipcc.ch. See also McMichael, op. cit, pp. 283-317.
7 --McMarthy, M.: "Uncertain impact of global warming on disease", The Lancet, 14-4-2001, 357: 1183.
8 --Lindgren, E. and Gustafson, R., The Lancet, 7-7-01, 358: 16-18
9 --Martens, P., "How Will Climate Change Affect Human Health?", American Scientist, Nov.-Dec., 1999, 87: 534-541
10 --Pascual, M., Rodó, X. et al.: "Cholera Dynamics and El Niño-Southern Oscillation", Science, 8-9-2000, 289: 1766-69
11 --McMichael, op. cit., pp. 68-70
12 --Paper presented at the American Psychiatric Association 19 May 1999. Quoted in the Otago Daily Times. Online Edition, 20-5-99
13 --Longnecker, M.P. et al, The Lancet, 14-7-01, 358: 110-114
14 --Braña, F.-J. (co-ord.) (1997): "Análisis económico de los estilos de vida: externalidades and coste social", Civitas, Madrid.
15 --Ibid, p. 30
16 --Le Monde, 28-7-01, p. 1
17 --El País, 27-7-01, p. 24
18 --Barendregt, J. J. et al.: "The health care costs of smoking", The New England Journal of Medicine, 1997, 337: 1052-57
19 --Hutton, G.: "Cost-effectiveness of environment health interventions", www.who.int/environmental_information/Disburden/WSH00-10
20 --Ibid, p. 74
21 --In some cases, the increase in cases of skin cancer may also be due to the migration of people with more sensitive skin and thus unadapted to places with more intense radiation.
22 --A paper on the relationship between the ultraviolet radiation gradient and multiple sclerosis can be found in McMichael, A.J. et al, "Epidemiology", 1997, 8: 642-645
23 --Cifuentes, L. et al: "Hidden Health Benefits of Greenhouse Gas Mitigation", Science, 17-8-01, 293: 1257-59
24 --"The particulate-related health benefits of reducing power plant emissions", Clean Air Task Force, Boston, 2000, www.cleartheair.org
25 --Mielke, H.W.: "Lead in the Inner Cities", American Scientist, January-February 1999, 87: 62-73.
26 --Thomas, V.M. et al, "Environmental Science & Technology", 1999, 33: 3942-48. Amongst other studies referring to Catalonia also included in this paper, see Domingo, J.L. et al. Science of Total Environment, 1996, 184: 203-209 and Environment International, 1995, 21: 821-825 and Rodamilans, M. et al, Bulletin of Environmental Pollution Toxicology, 1996, 56: 717-721
27 --"Rogan, W.J. et al, The New England Journal of Medicine, 10-5-01, 344: 1421-26
28 --Benkimoun, P., Le Monde, 30-6-2001, p. 20. A complete report can be found at: www.ineris.fr/
recherches/diesel/diesel.1htm
29 --Avui, 2-6-2001, p. 32.
30 --A very comprehensive paper is by Leon, D. and Walt, G. (pubs.): "Poverty, inequality and health. An international perspective", Oxford University Press, 2001.
31 --Ezzatti, M. and Kammen, D.M., The Lancet, 25-8-2001, 358: 619-624
32 --WHO, Press release/56, 14-9-2000
33 --"Paracelsus and Goethe: founding fathers of environmental health", Bulletin of World Health Organization, 2000, 78: 1162-64

Environment as a determining factor of health
Maria Rosa Girbau and Katy Salas
Lecturers at the Escola Universitària d'Infermeria (University College of Nursing), University of Barcelona

The state of the environment is a key factor for the well-being of both individuals and society as a whole. Moreover, many experts defend the idea that a suitable environment is a fundamental human right and this has been acknowledged by the Catalan Parliament. The writers of this article explain the hazards that are affecting the environment and that consequently pose a threat to people's health.

Up until the first half of the twentieth century, man paid little attention to the consequences of his impact on the environment and it was only after the Second World War that people began to be aware of the implications of man's actions on the environment and people's health.

Certain events, such as the nuclear bombs on Hiroshima and Nagasaki, the oil crisis and the foreseeable depletion of other minerals, the destruction of the ozone layer, proof of climatic change, the hazardousness of many natural and synthetic products, unpredictable natural disasters, the new strain of Creutzfeldt Jakob disease, etc., have all made it very clear that indiscriminate action by man on the environment has a boomerang effect that directly works against man himself. The words of ecologist Ramon Margalef are poignantly fitting, "Maybe it is us who are the planetary cancer, and it is our quality of life and survival that are endangered and not that of planet Earth".

The environment has been considered a determining factor of people's health for many years although it was not until the 1970s that different models appeared to explain the causes of health impairment in inhabitants in the developed world. Some of these models pointed to the holistic component (Laframboise 1974) as being the cause of disease-related mortality while others referred to the ecological model (Austin and Werner 1973), and that of well-being (Travis 1977).

Regular advances were made concerning the genesis of contemporary diseases on the basis of these initial contributions and in 1974 the Canadian Minister of Health Marc Lalonde, who had worked on developing previous models, presented a report on the health of the population in Canada entitled "New perspectives on the health of the Canadian population". The report described genetic factors, environmental factors, lifestyle and the health system as being the main determinants. New concepts concerning the determinants of health have appeared in recent years and can be classified on five different levels: biological, physical and psychic determinants; lifestyle determinants; environmental and community determinants; physical environment, climate and environmental pollution determinants; and, lastly, the factors determining macrosocial structure, politics and a population's outlook on life.

The environment is thus clearly a fundamental element affecting the wellbeing of both individuals and society as a whole, which calls for a new kind of environmental awareness based on shared responsibility, which in turn involves a change in people's attitudes based on the principle of environmental solidarity.

In this respect, the Secretary General of the United Nations Organisation (UNO), Kofi Annan, at the World Summit on Social Development in 1995, contended that "a healthy society is one that takes care of its members and gives them the opportunity to participate in the decisions that affect their lives" and therefore their health.

At the same time, one should be aware that both social and economic well-being are concepts that progress in tandem with sustainable development although it is very clear that people are not sensitive to the question of environmental problems until these are defined and socially accepted, which shows the importance of the media in making people aware of the hazards.

From an initial overall view of the human being, health is understood to be a process of balance or harmony between the different dimensions that make up the individual and his or her external environment. Man is a key element in maintaining the necessary balance and it stands out that the physical, biological and social environment plays a highly important role in contemporary disease and illness (cardiovascular, respiratory, and digestive problems, cancer, allergies, spongiform disease, etc.), with new problems being generated in the realm of public health.

On the basis of these considerations, there is a need to involve the different institutional, social, political, economic and professional actors for it is these who ultimately are directly or indirectly responsible for people's health.

Historical background

The oldest known reference to the relationship between man and the environment dates from the 5th century BC. The Treatise on Airs, Waters and Places by Hippocrates (460-377 BC), states that, in order to understand health and disease, man must be studied in his normal state and in relation to the environment where he lives, together with the causes that have disturbed the balance between man and his external and social environment.

Hippocrates' ideas were applied to construe the environmental conditions of human life and they can thus be considered to be one of the earliest roots of human ecology, along with Aristotle's works on natural history.

This ecological approach has unfortunately not prevailed in the field of the health sciences that, for different reasons, have been highly influenced by physiology and the study of man's internal environment that began in France during the 19th century, and reinforced by the advances made in the 20th century in the field of diagnosis and therapy. At the same time, the role of the physical, psychic and social environment in the genesis of health or disease in man has been overlooked.

In 1948, the United Nations General Assembly adopted and proclaimed the Universal Declaration of Human Rights, in which the environment itself is not dealt with explicitly although note can be made of several of its articles in that they demonstrate institutional and governmental responsibility with respect to the protection of the individual.

Article 1 states that "All human beings… should act towards one another in a spirit of brotherhood". Here, the principle of solidarity is laid down.
Article 3 states that "Everyone has the right to... security of person", which therefore institutes the right to live with guarantees.
Article 6 states that "Everyone has the right to recognition everywhere as a person before the law". This can be understood to mean the right to be protected.
Article 21.1 states that "Everyone has the right to take part in the decision-making process...", which assumes that people must actively participate in decisions that may compromise their integrity.

From the second half of the 20th century onwards, the ecology movement, together with an increased awareness of environmental issues, led to the UNO taking initiatives and it was from this point on that a series of far-reaching international conferences began to be held. The first world summit, known as "Only One Earth", was held in Stockholm in 1972, with the object of assessing the hazards resulting from pollution of the human environment. The bases for achieving international agreement on issues involving the environment were established here, and it also led to the United Nations Environment Programme (UNEP) being established.

The differences and difficulties in reaching global agreements on the problems affecting both rich and poor countries, which still persist today, became evident at this international summit where Indira Gandhi is attributed with saying, "environmental problems in the developing countries are not the collateral effects of excessive industrialisation but a reflection of the inadequacy of development".

At the 30th World Health Assembly in the city of Alma-Ata (1977), the World Health Organisation (WHO) agreed to draw up a series of objectives for achieving health for all by the year 2000, amongst which appeared the preservation of the environment. In 1984, the European Regional Office drew up a list of 38 objectives, corresponding to Europe, that made explicit reference to the creation of healthy environments (objectives nos. 18 to 25).

Various other global conferences were held during the 1990s, including the International Conference on Health Promotion (Ottawa, 1986), the Montreal Protocol (1987) on the protection of the ozone layer; the Sundswall Conference (Sweden, 1991), and several preparatory ones preceding the Earth Summit in Rio de Janeiro in 1992, with the sole objective of making progress in the knowledge of environmental hazards.

The purpose of the Rio Summit (1992), or "Earth Summit" as it is known, was to achieve a balance between social and economic needs and environmental needs, and three fundamental documents were drawn up:

• Agenda 21, considered to be a declaration of principles based on a world plan of action for promoting sustainable development.
  
• The document on Climatic Change, with the objective of reducing the gases responsible for the greenhouse effect.
  
• The document on Biological Diversity, which exhorted countries to undertake measures to conserve plant and animal species, with a series of directives on the most sustainable ways of managing forests.

The "Earth Summit + 5" was held in New York in 1997, with the purpose of determining and recognising the objectives achieved in applying the agreements reached in Rio.

As far as Climatic Change is concerned, summits have been held in Kyoto (Japan, 1997), The Hague (2000) and Bonn (2001), with somewhat disappointing results.

Other interesting initiatives that have reinforced some of the proposals presented at the different international forums include the reports presented by the Club of Rome in 1972, including the one entitled "The limits of growth", which was updated in 1992 with the title "Beyond the limits of growth".

Also worthy of mention is the Brundtland Report (1987), which expounded the idea of "meeting present needs without compromising the ability of future generations to meet their own needs", and established the relationship between sustainable development and economic systems.

An example of a local level project is the one by the Barcelona City Hall known as Barcelona Agenda 21, in which the commitments to face the new environmental challenges of the 21st century, together with the social, urban and economic development of the city in a sustainable way with the environment, are made manifest.

Risks associated with unsustainable development

Man's egocentric activities imply a potential risk to the health of both individuals and society as a whole in that the environment in which we live is highly dynamic due to the action of different cycles (carbon, nitrogen, water, etc.). It is also highly complex because there is an exchange of energy and matter and, at the same time, a constant interrelationship of elements on the different gradients or levels in nature, and the effects of man can break the fragile balance of the environment and endanger its integrity.

The possibility therefore of man being able to live in healthy conditions depends on his ability to adapt to changing conditions, and this ability is related to physical, biological and social factors.

In general terms, pollution can be defined as the alteration of the properties of an environment due to the incorporation, generally as a result of the direct or indirect action of man, of particles, gas compounds, disturbances, materials or radiation that lead to modifications in the structure and function of the ecosystems affected.

When asking the question of what the potential risks to health are, certain factors need to be taken into account which are closely linked to how serious the effect is, such as:

• the characteristics and degree of solubility of pollutants
  
• the quantity of substance or pathogen
  
• the period of exposure to risk
  
• the mechanisms of action or toxicodynamics
  
• the defence mechanisms of the affected organ and/or tissue
  
• the entry route and subsequent transformation of the substance
  
• immunity characteristics, and other variables that make the individual more susceptible, such as age, previous pathologies, etc.

Atmosphere

The atmosphere is the layer of gas that forms a sphere surrounding the Earth. It is made up of a mixture of gases in variable proportions according to altitude (troposphere, stratosphere, mesosphere and thermosphere) and is responsible for the temperature.

Atmospheric pollution is the degradation of the layer of gases due to the increase of elements that are normally present or by the presence of substances and/or particles that are foreign to its normal composition. Air pollution is a process that begins with gas and/or particle emissions and man has been exposed to it since the discovery of fire, although unsustainable development has increased the quantity and quality of polluting agents and today affects both industrialised and developing countries.

The presence of pollutants in the atmosphere may be the result of natural causes such as volcanic eruptions, soil erosion, sand storms, earthquakes, anaerobic fermentation processes, plant pollination, etc. and/or anthropogenic and/or artificial causes, such as road traffic, industrial processes and power stations, domestic and industrial heating, waste incineration, nuclear testing, war, etc.

Man ingests different harmful elements by way of the respiratory tract (into the lungs by inhaling), by contact with the skin (cutaneously) and orally (by direct or indirect ingestion).

Inhalation: Gases, vapour, aerosols and particles in suspension can all penetrate the respiratory organs. Size and shape, together with an individual's respiratory parameters determine the levels of pollutant absorption and penetration to the deeper respiratory tracts.

Skin contact: Many substances can penetrate the skin, such as biocides and organic solvents. Factors to be taken into account are the condition of the skin (erosion of the skin makes absorption easier), body temperature and peripheral circulation (an increase in these leads to higher absorption).

Oral ingestion: This is the most frequent way that pollutant substances found in drinking water enter the body.
These substances are mainly metabolised by the liver, kidneys, lungs, skin and the gastrointestinal tract, with elimination occurring mainly via the urine and bile. The elimination of volatile and gaseous substances is by way of exhaling.

There are numerous effects of air pollution and it is both difficult to quantify them and to establish causal relationships. Mention should be made, however, of the fact that they are especially dangerous for people with chronic pulmonary illness (emphysema, bronchitis, asthma), for the elderly and for babies. According to the WHO, between 30-40% of the cases of asthma and 20-30% of all respiratory problems may be related to air pollution in certain towns and cities, and it is considered to be one of the main causes reducing life expectancy in general, together with non-disabled life expectancy.

Some of the most significant aspects due to its effects on health are as follows:

• Carbon monoxide (CO): non-water soluble in the mucous membranes of the respiratory apparatus, which facilitates its ability to penetrate the alveolar walls, with a great affinity for one of the four iron atoms in the haemoglobin molecule (210-240 times more than oxygen molecules), which transforms it into carboxyhaemoglobin. This interferes with the correct exchange of gases in the capillaries and produces anoxia due to lack of O2.
  Clinical manifestations include cephalalgia, dizziness, faintness, nausea and vomiting. Serious intoxication can lead to cardiac irregularities due to myocardial ischemia, which can cause angor and infarct; neurological disturbances with obnubilation and coma; cutaneous irregularities, with pallor and cyanosis; and psychomotor dysfunctions with co-ordination impairment.
  
  
• Sulphur oxides (SOx): water-soluble, which facilitates absorption in the upper sections of the respiratory tract, causing irritation of the mucous membranes and bronchial constriction. Clinical manifestations may worsen if they interact synergically with other particles in suspension in the atmosphere, which facilitates penetration to the alveola. They also stimulate the taste and smell senses.
  
  
• Nitrogen oxides (NOx): non-water soluble in the mucous membranes of the respiratory apparatus, these penetrate the alveolar walls, where they combine with haemoglobin (Hb) and are transformed into nitrosamines with carcinogenic properties. Clinical manifestations include irritation of the mucous membranes, pulmonary edema, chronic pulmonary fibrosis and death due to asphyxia.
  
  
• Tropospheric ozone (O3): a secondary pollutant formed by the action of ultraviolet radiation on the oxygen molecules, which transform by dissociation into two reactive atoms that subsequently combine together with other oxygen molecules to form an ozone molecule. It is insoluble, which facilitates penetration in the respiratory tract. Clinical manifestations include irritation of the mucous membranes, dry throat, cephalalgia, fatigue, decline, an increased breathing rate, a decrease in the pulmonary function, and it is even related to a decrease in the ability to concentrate.
  
  
• Solid particles: the degree to which these have an effect is in relation to their ability to penetrate the pulmonary cavities, which has to do with molecular size and their affinity with the humidity of the air. They can act as inert particle deposits on the alveolar walls, which hinders gaseous exchange. They can also affect people through the ingestion of foodstuffs made of ingredients affected by particles that have been absorbed by plant life through dry deposition.
  
  
• Others: such as fluorides, lead, mercury, cadmium and asbestos. As a result of their ability to volatilise, they are absorbed by breathing and can lead to irritation of the mucous membranes and respiratory difficulties. Some, like asbestos, are potentially carcinogenic.

With respect to the effects on the atmosphere, mention must be made of the influence of carbon dioxide (CO2), nitrogen oxides (NOx), methane (CH4), chlorofluorocarbons (CFC) and ozone (O3) on the greenhouse effect. This is the increase in temperature due to the presence of gases in the layers of the atmosphere that prevent infrared (long wavelength) radiation from escaping out into space, which contributes to the warming of the atmosphere.

Its effects on health are linked to shifts in the increase of average air temperature, with alterations to ecosystems and loss of biodiversity. This therefore hinders the availability of food resources, the destruction of natural habitats due to the increase in sea-level (which in turn contributes to human migrations) and an increase in diseases transmitted by vectors (malaria), due to the increase in humidity.

Predictions are constantly being made in order to assess the impact according to the different potential scenarios (population, radiation, humidity, precipitation, erosion, agriculture, forests, absorption mechanisms in plants and oceans, etc.).

The presence of chlorofluorocarbons (CFCs) in the layers of the atmosphere causes depletion of the ozone layer situated in the stratosphere and formed of O3. The depletion of this layer is produced by the action of CFCs, which are highly volatile and chemically stable gases used in refrigeration units, pesticides, air conditioning, aerosols, foam, etc. On reaching the stratosphere, they are broken down by the action of ultraviolet rays and give off chlorine and bromide molecules that destroy the ozone.

This layer is vital for living beings in that it protects them from the sun's ultraviolet radiation. The decrease in stratospheric ozone is connected with the appearance of melanomas, cataracts and inhibition of the immune system.

Other harmful effects are due to acid rain, which leads to the acidification of the components in ecosystems; temperature inversions, which impede the vertical circulation of pollutants and their dispersion; and photochemical smog, with clinical manifestations in the form of coughs, nose and throat irritation, bronchial constriction, visual impairment and inability to concentrate.

The vulnerability of plants to atmospheric pollution must also be taken into account. They can suffer from growth retardation, yellowing of the leaves and death in extreme situations. Animals as well are vulnerable and they can undergo a decline in productivity, breeding irregularities and death by poisoning on ingesting contaminated plant matter.

The most outstanding material effects are the social consequences of the loss of architectural and artistic heritage, together with the cost of restoration and maintenance of damaged structures.

Water

Water is essential for life. All living beings are made predominantly of water and it is the most abundant substance on the planet, two thirds of which is covered with water. 97% is found in liquid form in the ocean, 2.25% is in a solid state in the ice caps, glaciers and in the form of snow, a small quantity occurs in the form of vapour in the atmosphere and a mere 0.75% is fresh water apt for human consumption when it is not polluted, in rivers, lakes and underground aquifers.

A human being can survive with between 2.5 to 5 litres of water per day. However, the demand in industrial societies can reach 500 litres per person per day, taking into account all types of use and is also the most demanding in terms of quality. The growing demand increasingly reduces the time taken between the disposal of water supplied and the next time it is used. The problem is thus one of quality and quantity.

In historical terms, water has played a very important role in the health of the world's societies. 80% of all illnesses in the world are directly or indirectly related to water (due to floods; drought; the transmission of epidemics such as cholera and other diarrhoea-causing illnesses; as a habitat for insects that transmit diseases such as malaria, dengue, Rift Valley fever, etc.).
On the other hand, the introduction of personal hygiene, public sanitation and advances made in microbiology have made an enormous contribution to improving the quality of life and health of the world's population.

Water is therefore a precious and scarce asset. So much so, in fact, that the European Water Charter was proclaimed in Strasbourg in 1968. Point 1 states that "there is no life without water and it is a treasure indispensable to all human activity". It ends with point 12 that states that "Water knows no frontiers: as a common resource it demands international co-operation".

Sources of water pollution

Polluted water is hereby understood to mean water containing substances that are alien to the natural composition of water and/or micro-organisms that may represent a hazard to people. In this case, it cannot be used for drinking, cooking, irrigating crops, or in the food industries.

• Pollution of urban origin: this results from all of the activities in a town or city used fundamentally for domestic, commercial, small industry, public infrastructure and transport purposes. This type of waste water may carry a biological and chemical load.
  
  
• Pollution of industrial origin: given the wide variety of different industrial processes, waste water originating here may contain a chemical load (heavy metals, various types of compound, etc.), a physical load (increase in temperature, radioactivity) and a microbiological load (bacteria, viruses, fungi, etc.). In spite of environmental protection laws, the disposal of industrial waste water continues to present a high risk for rivers, lakes and the sea, and thus for human health.
  
  
• Pollution of agricultural origin: the great increase in the use of chemical fertilisers to make crops more profitable, together with all types of biocides to prevent plagues and disease from affecting plants, has led to a great increase in the pollution of run-off water and groundwater.
  
  
• Pollution of livestock origin: liquid manure that is generated on today's intensive livestock farms is a real problem in terms of elimination due to the high content of nitrogen and other compounds, together with the microbiological load.
  
  
• Marine pollution: considering that coastlines are often highly built up and industrialised areas, the waste water from these areas is the main source of pollution constantly affecting marine waters but not the only one. The maritime transport of passengers and goods is the other source that all too often has been the origin of important ecological disasters, such as spills of oil and other hazardous substances into the sea due to accidents, or the cleaning of tanks at high sea by oil tankers (which quite naturally is prohibited).

Types of pollutants

Pollutants in water can be biological, chemical and physical.

Biological pollutants: these are microbiological agents capable of causing infectious diseases in man and animals. They can be classified as:

• Bacteria: such as, for example, Vibrio Cholerae that produces cholera, an infectious disease that causes vomiting, fluid evacuations that are similar to rice water, acidosis and muscular cramps; Salmonella typhi, which causes typhoid fever that comes on with the sudden appearance of fever, asthenia, exanthema in the thorax and abdomen, hepatosplenomegaly, and diarrhoea, as well as unconsciousness, and other types of salmonellosis, etc.
  
• Viruses: such as, for example, the hepatitis A virus, an infectious disease that spreads by orofecal transmission, with a period of incubation of between 15 and 60 days and produces fever, symptoms of discomfort and non-specific digestive disorders and jaundice. It is endemic to the Mediterranean basin. Enteroviruses: these cause digestive irregularities. Adenoviruses: these cause adenoidal and amygdaloid irregularities. Reoviruses: these can cause intestinal and/or respiratory irregularities.
  
• Parasites: such as, for example, various types of amoebiasis, that cause a dysentery-type syndrome that can subsequently spread and affect other organs like the liver, lungs, kidneys, brain, etc, with amoebic abscesses being produced. Helminthiasis (due to intestinal worms) can occur in different phases of its life cycle (egg, larva, adult, etc.).
  
• Fungi: these reproduce by way of spores and some may be pathogens for man and animals. They live in humid conditions, such as, for example, around the edges of public swimming pools or on the ground where there are public showers (athlete's foot).

Chemical pollutants: these are chemical elements or compounds found in water from different sources that may be toxic for human beings, animals, and aquatic flora. Contact is either by ingestion of contaminated water, through the skin and/or mucous membranes, especially if these are impaired in any way (wounds, cuts, erosion, etc.), and by inhaling vapours or aerosols.
The repercussions that a particular chemical substance can have on a person's health will depend on: its chemical form, its concentration, the form of contact, the transformations it may undergo, either due to reaction with other substances or processes of accumulation in the food chain, and the susceptibility of the individual or group.

The most common pollutants are:

Nitrates: the concentration in surface waters is usually below 5 mgr/litre. These concentrations can be much higher in groundwater. Direct consumption or food preparations for babies (feeding bottles) using water with high nitrate concentrations can cause methaemoglobinaemia (cyanosis due to hypoxia).

Fluorides: These are salts used in a wide number of industrial processes, in chemical synthesis, insecticides, pesticides and rodenticides. While fluoride is considered to be essential in preventing dental decay, in high concentrations it can lead to fluorosis, which is characterised by loss of weight, brittle bones, anuria, aesthenia, general discomfort, rigid joints, and discoloration of teeth in the formation stage.

Mercury, lead, cadmium, nickel and other metals: these are highly toxic and in general they tend to accumulate. Minamata disease (from the bay in Japan) is a serious and complex set of toxic symptoms, with nervous and psychic disorders due to the ingestion of mercury in the sea and/or water polluted by spillage from vinyl chloride industries. Saturnism is acute or chronic lead (or lead salt) poisoning and can be extremely serious. Cadmium can be found in water as a result of industrial spills and plastic and metal piping.

Arsenic: Therapy using arsenic has been used for over 3000 years although it is also a very well known poison (it is merely a question of dosage) that is highly toxic, produces vomiting, diarrhoea, the breakdown of fat in the liver, and weakness in the limbs and even paralysis.

Selenium: certain selenium salts, such as selenium sulphide, are used as a topical antimycotic for treating ringworm, as a keratolitic and in scalp disorders (seborrheic dermatitis and dandruff). In large doses it is highly toxic.
Organo-chlorate compounds: these are compounds found in insecticides, pesticides, the best known being DDT, aldrin and endosulphan. They are liposoluble and tend to accumulate. DDT has been found in the layer of body fat in penguins in the Antarctic.

Hydrocarbons: Numerous hydrocarbons, particularly benzopyrenes (which are potentially carcinogenic), have been found in seawater; they have a low solubility in fresh water although this can increase with the presence of anionic detergents (surfactants). These produce foam in the turbulent stretches of rivers and obstruct waste water treatment processes and the natural purification of currents. It has been compulsory for detergents to be biodegradable since 1960.

Physical pollution: the temperature of water varies according to the season of the year although if it is used as a coolant (in thermal power stations and nuclear power stations), the increase in temperature leads to an increase in solubility and alters the biological processes that take place in it (colonies of legionella can form in the open part of cooling towers for they need a certain temperature).

Radioactivity can occur in water for natural reasons (radioactive elements in the lithosphere) although it is normally found as a result of the radioactive activities developed by man.

Waste water treatment:

The large demographic increase, industrialisation and the intensification of livestock breeding and agriculture that occurred during the 20th century have, as a whole, by far exceeded the natural purification capacity of the water cycle, as a result of which water has to be treated artificially.

There are various processing techniques in waste water treatment plants, and these are either physico-chemical and/or biological.

Physico-chemical processing: in schematic terms, this consists of the initial filtering of coarse material, a second filtering of smaller material, a flocculation process (with ferrous sulphate or aluminium chloride), a sedimentation process and lastly a sand bed filtering process and then disposal into a river or sea by way of an ocean outfall at a distance of various kilometres from the coast.

In the case of waste water treatment plants, a preliminary chlorinating process is carried out after filtering to reduce the microbiological load. The sand bed may be replaced by an active carbon bed (that has a high absorption capacity) in the last phase, together with an oxidation process using added ozone, and a final chlorinating process that makes it apt for distribution to the mains network.

Biological processing is based on imitating natural purification. It basically consists of filtering, with the water being passed through pools of active clay (that contain bacteria capable of breaking down the organic material) and fat separators. It is then subjected to a sedimentation process and finally a decanting process.

Waste

Considering that the soil plays a key role in the exchange of material and energy and acts as an active receptor of all of the components in the air and in water, waste constitutes a reservoir of micro-organisms that are potentially hazardous and capable of infecting the population in general.

Man is an important factor that alters the dynamics of the soil, with waste being uncontrollably dumped on the environment as a consequence of the consumer model that modern day society has mistakenly chosen and considers to be the product of wellbeing.

There are many causes for the increase in waste that is turning the planet into a gigantic landfill site. This phenomenon is both of great concern and dangerous because eliminating, processing and recycling waste may compromise people's quality of life and impede the sustainable development that is so avidly sought after.

From this perspective, it is important to understand the main causes for the increase in urban waste in order to try and modify consumer attitudes, reduce the volume of waste at source, and encourage waste reuse, recycling and exploitation.

These causes include:

• Hygiene and health needs, which have led to a spectacular increase in the use of packaging and wrapping to prevent the risk of contamination in handling and incorrect storage.
  
• The change of eating habits, with an increase in the consumption of fast and pre-cooked food.
  
• Urban growth due to migration from rural areas, together with the demand for services and an increase in consumption.
  
• The consumer society, with its "use and throw away" habits, and an increase in the use of paper, glass, plastic, cans, PVC, etc.

At the present time, five million people die every year as a result of diseases connected with waste and a thousand million people are lacking any type of garbage collection service. This is particularly serious in the developing countries and makes the world's population highly vulnerable to different pathogenic micro-organisms through the food chain or by direct contact.

Helminthiasis, salmonellosis, ancylostomiasis, anthrax, leptospirosis, tetanus, opportunistic mycoses, and toxoplasmosis, are just some of the diseases that human beings can contract this way.

Different types of waste (urban and municipal, industrial, radioactive and clinical) are generated by human activities, and the risk that they present depends on the characteristics of the waste and how it is processed. From the public health point of view, however, care needs to be taken with the ways that waste is eliminated in order to guarantee that it is totally harmless during collection, transportation and final disposal.

Selective collection (of glass, paper, plastic, cans, tetra brik aseptic cartons, organic waste, medicaments, batteries, fluorescent light bulbs, oil, domestic appliances): this is the most plausible means of recovery because it reduces the volume of municipal waste, the consumption of energy, water and raw materials, gas emissions, the consumption of chemical fertilisers, it reduces pressure on landfill sites and incineration, it impedes the presence of vectors and reservoirs (rodents, fleas, arthropodae), and provides social benefits by creating jobs in the recycling industry.

Different ways of eliminating waste are as follows:

• Controlled landfills: this entails difficulties, such as finding new spaces where they can be located at a reasonable cost, places that are geologically adequate and also willingly accepted by the neighbourhood.
  
• Incineration: this way of partially eliminating waste is not totally risk-free for public health because potentially carcinogenic substances like dioxins are emitted into the atmosphere. A large proportion of clinical waste contains chlorine, an element that remains undestroyed and forms hydrochloric acid which can pollute the atmosphere.
  
• Underground confinement and tanks: radioactive waste in Spain, particularly that produced by nuclear power stations, is managed by the firm ENRESA. The risks involved with this elimination technique are difficult to assess because little is known about the long-term effects (radioactive particles have a very long half-life).

Noise as a source of pollution

Sound is the sensation that an animal perceives by way of its hearing as a result of a disturbance in the pressure and density in the material environment that surrounds it (gas, liquid and/or solid), caused by a vibration that spreads out in the form of a sound wave.

Two characteristics of sound are particularly interesting here:

1. Intensity: the degree of loudness of the acoustic vibration or pressure, together with the alteration that is produced in the air. It is measured in terms of dB (decibel) units. The measurement scale is logarithmic, as to an arithmetic one, which means that an increase of 3dB is equivalent to doubling the intensity of the perceived sound.

The maximum permitted level, according to legislation in Spain, is 85dB over 8 working hours. Measures must be taken to reduce noise above this level.

The threshold level for hearing in human beings (young people) is above 0, and the pain threshold is 125dB.

2. Frequency: this is the number of vibrations or cycles produced per second. This is what is known as pitch, which goes from very low frequencies (low pitch) to high frequencies (high pitch). The vibrations are measured in Hz (Hertz). The human ear (a young person) can hear deep sounds from 20Hz (frequencies below these are known as infrasound), at the lower end, and up to 20,000Hz (above these are the ultrasounds) at the high end.

Sound is one of the main forms of communication between animals and human beings but it turns into noise when we perceive it as being uncomfortable or when it produces a sensation of anxiety or repulsion; it can even cause pain. The unpleasant sensation that is perceived can produce a subjective (individual or cultural) and/or objective (well-informed) disturbance to a person's physiology and behaviour that is/are observable and/or measurable.

From the point of view of public health, continual exposure to noise both at and away from work has become so important that a Congress on Noise as a Public Health Problem was held in Washington in 1974. Two years prior to this in 1972, it was recognised as being a pollutant of the first magnitude at the Environment Summit held by the United Nations in Stockholm. The WHO has estimated that there are 120 million people in the world who have disabling hearing difficulties.

Noise forms part of most activities in urban life and this holds true for the past as well as the present. In ancient Rome, as well as in medieval cities, regulations existed to control both carriage transit and working activities that were a nuisance to the inhabitants.

With industrialisation, the sources of noise pollution have increased in quantity and variety. The main ones are: the transportation of people and goods in both developed countries and large cities in the developing world (cars, motorcycles, buses, coaches, trucks, conventional and high speed trains, and planes), industry (machinery in operation), the building and public works sector, leisure and entertainment installations (bars, discotheques, open air restaurants, etc.), noise in the home (domestic appliances, radio, TV, hi-fi, air conditioning, lifts, etc.) and in offices (printers, photocopiers, drinks machines, etc.).

The harmful effects of noise:

Aside from being a nuisance, noise is also a risk to health. The effects of noise can be divided as follows:

a) Specific effects on the hearing organ, b) effects on the physiology or functioning of the rest of the organism, c) effects on behaviour and activity.
a)

• Continuous exposure (8 working hours) to noise louder than 85-90 dB constitutes a high risk of deafness at work that in general is bilateral and irreversible in the frequency bands of this type of noise.
  
• Occasional exposure to loud noise (95-100dB) of different frequencies similar to discotheque music produces what is known as hearing fatigue. This causes a temporary loss of hearing ability, with the recovery time being directly proportional to the time of exposure.
  
• Exposure to a sudden short noise (pistol shot, firecracker, hammer blow, a bomb explosion or a gas bottle explosion, for example) can produce a hearing trauma that causes total deafness if it is loud enough and if the individual affected is close to the source. This is a result of the mechanisms of perception of the vibration and transmission of the nervous impulse being affected, and is more or less reversible.

b) Continuous exposure to noise is described as being able to cause arterial hypertension or ischemic cardiopathy in the cardiovascular system. In the respiratory organs, it can produce apnea when the noise is sudden and tachypnea (an increase in the respiratory rate) when it is continuous.

Symptoms affecting the digestive system include a reduction in saliva secretion, vulnerability to gastric ulcers, a decrease in intestinal peristalsis, sluggish digestion, and nausea including vomiting.
Increased secretions of cortisone and adrenaline can occur in the endocrine system. This is of special importance to pregnant women as it can lead to a decreased irrigation in the womb and placenta, with an increase in the cardiac rate of the foetus. The possibility of an increase in glycemia has also been described.

Sound can affect the central nervous system in the form of insomnia, anxiety, irritability and a decrease in the ability to concentrate.

Eyesight problems have also been observed, with a decrease in the field of vision, difficulties in distinguishing colours and a decrease in night vision, which may represent a hazard when driving.

• Impairment of balance due to dizziness.
  
• Increase in muscular tension.
  
• Increase in skin sensitivity.

c) As far as behaviour and activity are concerned, it is a fact that a noisy environment impedes interpersonal oral communication. People become more nervous and aggressive, they show signs of fatigue and emotional lability.
Background noise makes concentration and learning difficult. The risk of making errors increases at work, together with the likelihood of a higher accident rate.

Emphasis must be placed on the individual and cultural variability that exists in perceiving sound as noise and in the effects it has on health.

Preventive measures:

Different types of measure can be adopted:

• Technical: insulation at source (machinery can be insulated inside cabins; shock absorbers can be used to reduce vibration; screens can be used to separate them, etc.). Protection for people (helmets, earphones or earplugs). Buildings (both working premises and housing can be built with insulation materials, and carpets, curtains, wall hangings, etc. used to deaden sound as well as being decorative).
  
  
• Legislation: the drawing up of national, regional and municipal regulations on noise generated by different sources.
  
  
• Education is perhaps the most effective way of avoiding unnecessary noise at its source. The benefits of educating people to respect the environment are there for all because the behaviour of society as a whole is the sum of all individual behaviour.
  We believe, however, that the best strategy would be to incorporate new consumer values in society and to develop attitudes that are much more respectful of the environment in order to be able to continue to enjoy this precious treasure that we have been given in the future. As Einstein used to say, "An intelligent man is one who solves problems, a wise man is one who avoids them".

Bibliography

• FOLCH R. Planeta Viu. Barcelona: Fundació Enciclopèdia Catalana; 1998.
  
• GIRBAU Mª R., SALAS K. Salut i Medi Ambient. Text-Guia. Barcelona: Edicions Universitat de Barcelona; 2000.
  
• LUDEVID M. El canvi global en el medi ambient. Barcelona: Proa-Universitat Pompeu Fabra; 1995.
  
• W.H.O. Pollution de l'Aire. Aide-Mémoire Nº 187. October 2000. Available at: http://www.who.int/inf-fs/fr/am187.html
  
• W.H.O. Les Déchets Liés aux soins de sante. Aide-Mémoire Nº 253. September 2000. Available at: http://www.who.int/inf-fs/fr/am253.html
  
• W.H.O. Rapport Annuel du Comité Européen de l'Environnement et de la Santé (CEES). Comité Regional de l'Europe. 13 September 2001.
  
• W.H.O. Résumé d'orientations des Directives de l'OMS relatives au bruit dans l'environnement. Available at: http://www.who.int/environmental
  
• W.H.O. Le bruit au travail et le bruit ambient. Aide-Mémoire Nº 258. Available at: http://www.who.int/inf-fs
  
• PIEDROLA G. Medicina preventiva y salud pública. 10th ed. Barcelona: Masson-Salvat Medicina; 2001.
  
• TÀBARA D. La percepció dels problemes del medi ambient. Barcelona: Beta Editorial-Generalitat de Catalunya; 1996

Influence of the Environment on the Relationships between Food and Health
Abel Mariné Font and
M. Carmen Vidal Carou
Departament de Nutrició i Bromatologia. Universitat de Barcelona (Department of Nutrition and Bromatology. University of Barcelona)

Food is one more link in the environmental chain and is therefore subject to the negative effects of pollution. There are positive interactions as well, but today consumers are concerned with the safety or innocuousness of the food they eat. The authors describe the main contaminants, they introduce the concept of the risk/benefit balance and they offer assurances that, in general, the food we eat is reasonably safe.

1. Introduction

"If I listened to everyone, the solution would be to not eat anything, and that certainly isn't good"
(J. Mª Espinàs)

The environment has an inevitable influence on food that is often positive but at other times is negative. This interaction, in addition to reasons of availability, could have cultural repercussions in regard to the choice of nutritional food as, for example, possible deficits associated with a certain geographical area, as well as toxicological deficits due to the potential presence of contaminants or, more generally, xenobiotics1 in food. Despite it being undeniable that the environment is the main provider of xenobiotics in our food, it should also be remembered that some of them, especially vegetables, naturally contain microcomponents that, in relatively high doses and/or under certain conditions, could give rise to undesirable and even toxic effects on consumers.

When considering the relationship between food and the environment, the first thing one thinks of is just the negative effect. Certainly, environmental pollution is an important problem today that requires specific action, and the fact that food is in fact another link in the environmental chain make it impossible to isolate it from this pollution. It would not be fair, however, to fail to recognize that environmental influences on our food go well beyond this, and not just with negative connotations, but in many cases there are positive interactions as well.

When food is valued, consideration is given not only to nutritional value and sensory or organoleptic2 qualities, rather, and above all, its safety must be guaranteed, which means it must be innocuous. In fact, safety has always been a condition closely linked to food, in the sense that, because it is considered as such, it must not produce any type of undesirable effect on consumers (as long as consumption is rational).

Currently, our developed society shows great concern for health and, along these lines, once the multiple relationships existing between food and health are acknowledged, interest, and sometimes even anxiety, is sparked by all matters affecting, more or less reliably, food safety. Obviously we cannot sit before a plate of food and think about all it could contain that could be harmful to our health. In the same way, it makes no sense to sit before each meal with a calculator in order to make sure that the combination of products chosen covers all nutritional needs. Surely the probability of suffering undesirable psychological consequences due to this type of behaviour is greater than the risk this behaviour tries to prevent. In fact, as pointed out by Bello et al. (2000), "concern for the safety of what is consumed has accompanied man from his first steps on this planet. Therefore, throughout history, man has been making a selection of raw food materials to provide him with a healthy state of wellbeing, while rejecting others that caused undesirable effects".

From this perspective, one can understand that every new food raises suspicion and distrust while, on the other hand, what has always been around -classic and traditional foods- inspire greater trust. Therefore, consumers find themselves faced, against traditional safety, with the uncertainty of possible risks associated with technologies applied to improve animal and vegetable production, all this without forgetting that food production cannot be isolated from the existence of a degree of environmental pollution that is hardly to be undervalued.

Bello et al (2000) point out that the concept of food contamination has yet to be given a concrete, satisfactory definition, to the point where its meaning can vary from one country to another. Therefore, in this article we will see that many possibilities fit under the heading of contaminant, not only in regard to structure or chemical nature, but also according to its origins, contamination routes, level of "danger" to human beings, etc.

2. Influence of the environment on food

The relationships between environment and food can be approached from different points of view:

a) the environment influences the selection of foods
b) the environment determines the type of foods available in a certain geographical area, which in turn strongly conditions eating habits.
c) the environment can affect the nutritional composition of food (especially micronutrients).3
d) the environment can be a direct or indirect source of food contamination.

Climate, temperature, sunshine, ambient humidity… all are highly influential in the type of food available to make up a diet or portions. There is no need to search in far-away countries, as this can be seen even within Spain, where the dietary peculiarities of the north and the south respond to their respective environmental conditions. So for example, a preference for vegetables in the south, compared to the dietary habits in the north, is a reflection of this question. Even within one geographic area there can be noticeable differences in food uses between urban or rural areas. But if climate and the environment in general are important factors in choosing food, they may be even more important in regard to the type of foods produced in each geographical area.

The environment influences the availability of foods qualitatively and quantitatively; or rather, it influences the type and quantity of foods that can be consumed (available). This influence can be appreciated in the food obtained in each geographical area as well as in the type of preservation techniques applied. Therefore it is evident that, depending on the ease of access to the sea or rivers, food may be more or less rich in fish and other products of the sea. Likewise, the basic foods of towns where cereals are easily grown will not be the same as those of colder areas in which this type of crop does not grow well. There are many agronomic matters that influence vegetable production: type of land, altitude and latitude, climate (rainfall, temperature, amount of sunshine, etc.).

All this can determine whether or not certain species and varieties of vegetables grow. Some may think that this could have mattered in the past but today is totally irrelevant given the ease with which products are traded among different countries. Certainly this is true to a degree, but the characteristics of food marked by the environment have in many cases been tied to the cultural aspects and idiosyncrasies of each area. On the other hand, the fact that even in the same geographical area environmental conditions can change from one harvest to the next gives an idea of the complexity of these influences, and makes it almost impossible to obtain products that are always identical, especially in regard to microcomponents of nutritional interest (vitamins and some mineral salts) or sensory or organoleptic interest (components of the taste-smell fraction). The environment directly influences the type and extension of crops that can be grown, but this is also directly and indirectly true in animal production.

The effect of environmental conditions on food conservation methods must be explained starting with the historical origin of their uses. Therefore, it is well known that in warm, dry countries, desiccation was a preservation technique employed since antiquity; in maritime areas salting was used, and in cold and frozen areas, refrigeration and freezing were used. Technological development expanded the possibilities of preservation, particularly since the discovery in the last century of methods for applying heat and, above all, since the beginning of this century, when cold was able to be "manufactured". Yet, there is still a tendency, as if it were a cultural background, to prefer using one of the classic techniques from the regions in which the geographic and environmental surroundings favoured them, for example, smoking in Northern and Central Europe.

It is clear that preferences as well as the availability of foods condition eating habits, and these are logically critical to the nutritional condition of individuals and populations, and their health and wellbeing can depend on good dietary habits. If we had to choose today which of these two factors has more effect on nutritional conditions, without doubt we would have to choose preferences. In fact, the availability of food can characterize one food model as opposed to another, but this does not necessarily imply negative comparisons. Rather, the models may be different, but all of them suitable.

The argument for this axiom is as simple as acknowledging that, if it were not so, we would not have reached our present time. This means that man adapts to his environment and, by taking on and properly combining the products afforded him in this way, he can choose the right basic foods. Nevertheless, having established the rules, the exceptions must also be allowed. This means cases in which a truly insufficient availability of food negatively conditions the nutritional condition of individuals and populations.

Perhaps one of the best-known cases is the iodine deficiency of certain populations that normally live in mountainous areas, far from the sea, which is the most important natural and dietetic source (fish and shellfish) of iodine. These populations suffer more often than usual from problems of endemic goitre.4 This, in addition to the scarce consumption of fish and the relatively high consumption of certain vegetables (also low in iodine because they are cultivated in soil that is poor in this element), legumes and cruciferae (cabbage and the like) that also have a certain goitrogenic effect because they contain microcomponents that impede or inhibit thyroidal iodine capture.

The availability of certain foods is one of the pillars supporting the so-called "Mediterranean diet" which, in truth, is not just one diet and, when understood properly, is much more than a diet; it is a lifestyle. The environmental conditions of the Mediterranean area permit the cultivation of numerous vegetables, including the noteworthy olive tree (a true symbol of the Mediterranean) and grapevine. The availability of olive oil in the Mediterranean area has been, and still is (despite the fact that globalizing trends also affect diet), a determining factor in the population of this area consuming less animal fat than our neighbours of Central and Northern Europe.

The fact that in the Mediterranean area cultivation takes place mainly in orchards, because the geography does not allow for large expanses of crops, as it does not for large stock farms, very probably favoured the variety that characterizes the food in this region. The renowned beneficial effects of the Mediterranean diet, which protects against several of civilization's illnesses (cardiovascular disorders, certain types of cancer...), give weight to the argument for the diet-health binomial and permit the latter to be positively correlated with the environment by means of food.

3. The Environment as Source of Food Contamination

"Bless, Lord, but above all analyse, the food we are about to eat" (Perich, 1992).

In addition to what may be called the "natural influence" of the environment on food, the effect of environmental contamination on our food cannot be ignored, even less so today, because it is a fact that most food contamination comes directly or indirectly from the environment. Even so, it is also fair to acknowledge that, in most cases, the environment is really a storehouse for pollutants that are a direct or indirect consequence of human activity.

3.1. Type and Origin of the Main Contaminants of Environmental Origin that Reach Foods.

Food contaminants can belong to two large groups or categories: biotic and abiotic. The term biotic refers to living beings, and in the case of food contamination, it especially includes microorganisms (bacteria and viruses) and parasites. The name abiotic contaminant is given to chemical substances that can be accidentally introduced into food, the presence of which is normally associated with undesirable effects in consumers. The first thing to mention is that biotic contamination of food is quantitatively more significant than abiotic contamination, from the perspective of food alteration as well as consumer health. Table 1 summarizes the differentiating features between biotic and abiotic food contaminants.

It is often forgotten that bacterial contamination of food is, by far, the primary cause of health problems in regard to food consumption, much greater than problems such as salt or cholesterol content and, likewise, much greater than disorders that could be brought on by the presence of abiotic contaminants such as heavy metals, dioxins or halomethanes, to mention just a few examples. It is likely that all or many readers, through their own experience or that of people close to them, are familiar with the consequences of bacterial food contamination: gastroenteritis, diarrhoea, gastrointestinal upsets... By order of importance, Salmonellosis is the primary cause of food problems, followed by disorders caused by Staphylococci and Clostridia. Apart from these "classic" biotic contaminants, the so-called emergent pathogens should currently be added: Campylobacter, Yersinia, Listeria and certain strains of Escherichia coli, which is increasingly important and partially explains why the application of preventive hygiene measures to avoid the presence of classic microorganisms involuntarily favours the growth of emergent ones, which are less competitive than the classic ones but are more resistant to the usual measures to control bacterial growth. The number of toxi-infections produced is truly high: Spain registers approximately 12,000 per year, and it is estimated that this is only 10% of those that really occur. It may be that the high incidence with which they appear justifies the fact that consumers in general do not give it the importance it really deserves.

Although it is true that in some cases the disorders produced are slight and go away on their own, in others specific treatment is required and, on occasion, they can even be fatal. This possibility, however, is fortunately infrequent, due to the fact that there is a specific, effective therapeutic arsenal available.

The environment is not sterile, and that is why it is a potential source of biotic contamination. Whether or not it goes from being potential to real depends to a great extent on the habits, rules and precautions of hygiene practiced and, therefore, once again we find ourselves before a human attitude or activity that is a critical, key factor in the production of problems associated with this type of contamination. Likewise, it must not be forgotten that many microorganisms not only do not mean contamination but, contrarily, they can be useful to humans at many, and very different, levels.

Abiotic contamination of food may or may not come from the environment; however, as we will see later, the borderlines can sometimes be fuzzy. In order to differentiate contaminants from other possible "undesirable" components in food, we will highlight the characteristic of their entering food accidentally. This allows us to differentiate them, for example, from natural vegetable toxins, as well as food additives, despite the fact that people often consider them as contaminants, this really is not true in regard to concept, risk or, much less so, in regard to functions in food.

The case of the presence of pesticides in vegetable foods and of products with pharmacological activity in foods of animal origin is a good example for illustrating the difficulty inherent in setting boundaries that are too strict. Therefore, it is logical to think that if remains of these products are found in food, it is because they really were introduced previously, at some stage in obtaining it. In this sense, given the fact that there has been voluntary addition, they could not be considered contaminants. However, if the authorized products are found to be above certain limits, they should be considered as contaminants. And if the substances found were unauthorized, in this case they would also be considered as contaminants. The difficulty is even more obvious for indicating a defined frontier in the case of substances that, at certain doses, are considered normal in food and which, contrarily, above certain levels should be considered contaminants.

Other examples of dubious frontiers are substances that may appear in food as a result of technological or culinary treatment. How should we contemplate the aromatic hydrocarbons formed in smoked products or nitrosamines that can form as a result of the combination of food nitrates and amines? Are they or are they not contaminants? It is clear that they are undesirable because, without recognized positive effects, they are potential carcinogens or procarcinogens. Likewise, the frontier between biotic and abiotic is not always crystal clear. Mycotoxins (toxins from fungi), bacterial toxins, certain metabolites from bacterial activity, such as some biogenic amines, or saxitoxins (toxins of molluscs that have fed off of certain types of seaweed) are examples of contaminants of an abiotic nature whose origin is biotic. The question we should ask is, is it worth considering an environmental origin or relationship for these contaminants? With a different level of involvement, the answer would always be yes, as will be discussed later in sections on each type of contaminant.

3.2. Nature of the Main Environmental Abiotics and Factors determining their Level of Risk as Food Contaminants

Taking note of their chemical nature, abiotic food contaminants can be subdivided into two macrocategories: those originating in industry and present mostly in the environment, and those deriving from the agronomic, technological or culinary treatment of food, which may or may not become environmental contaminants. Depending on their nature, differentiations can be made among inorganic, organic and radioactive compounds (Table 2).

Despite the fact that they have a very different chemical nature, the aforementioned environmental contaminants originating in industry have certain characteristics in common, which are what mostly determine their harmfulness to the environment as well as to human health:

(a) These substances are very persistent in the environment. This means they have very long (chemical or biological) half-lives, which translates into a great deal of difficulty in degrading, making it possible for them to take dozens or hundreds of years to disappear;

(b) They are very difficult for living beings to metabolise and eliminate, and they usually accumulate in diverse organs or tissues, according to their affinity with them. Their high resistance to metabolism explains the bioaccumulation they undergo throughout the food chain.

(c) Their toxicity per unit of weight increases the further up the phylogenic scale they are. This means that sensitivity to these toxins is often greater in man than in phylogenically inferior animal species.

(d) They may undergo biotransformation processes in the environment, which eventually transform them into compounds that are more toxic than the original compounds.

Heavy metals may well be one of the best-known examples of environmental contaminants originating above all in industrial activity. This is not contradictory to their also being natural components of the earth's crust. This means that, despite the fact that there may be significant levels of these minerals in certain geographical areas, due to natural beds, their importance in food toxicology is due to their possibly being environmental contaminants of food.

Their presence in the environment is a result of (loosely controlled?) industrial dumping. In general, industrial effluents primarily affect surface water in land areas, and then seawater. This is why the food that is most susceptible to containing this type of contaminant is from fishing produce. Despite the fact that symptoms of poisoning are different depending on the metal in question, generalizations may be made about two common aspects: (a) the ability of heavy metals to inhibit enzyme systems and (b) their ability to accumulate in organs and tissues depending on affinity.

Of all metal contaminants, lead, mercury and cadmium are the most important in food toxicology. In regard to mercury, the main sources of environmental pollution are chemical, paper, bleach industries, etc., which dump inorganic mercury from the action of bacteria into an aqueous environment rich in organic matter, turning it into organic mercury (methyl mercury and others), which is liposoluble, more easily accumulated and, in fact, much more toxic to man than in inorganic forms. The name of the Minamata disease, from mercury poisoning, comes from the name of a bay in Japan where this cycle of mercury, which is really an environmental biotoxification of this element, was first discovered. Fish and other fishing produce living in contaminated waters are the main dietary source of mercury.

The case of lead is a paradigm of a contaminant whose presence in food has a basically anthropomorphic origin, but which in recent years has been the object of diminishing toxicological interest due to measures adopted by man to reduce this type of pollution. Therefore, for example, lead pipes for channelling water have been eliminated, lead in cans has been replaced with other types of metal, measures have been taken to prevent lead poisoning from migrating from ceramic cookware, etc. Despite the fact that solutions are being offered, the presence of lead in the environment continues to be a problem today as a result of the use of salts from this metal in mixtures used in petrol to prevent backfiring. It is a well-known fact that vegetables grown in rural areas have lower lead contents than those grown in plots near motorways or roads with heavy traffic.

What had become one of the main sources of lead pollution in the environment is today, thanks to the use of unleaded petrol, less and less of a problem. One source of lead that is arousing increasing interest is the contamination of game, soil and water due to the use of lead shot. The effect of this metal is to block enzymes that are essential to the synthesis of haemoglobin (pigment of the blood), giving rise to a disease called Saturnism and known as lead poisoning. Cadmium is another example of industrial contaminants (batteries and accumulators, industrial colours, plastics, mining, etc.). According to some data, ingestion of this metal comes close to the maximum tolerance levels indicated by WHO. Cadmium, in contrast to other metals, can pass from the soil to vegetables, with mud from river and sea beds being the most important source of this contaminant.

In short, we can highlight the conclusion that heavy metals are environmental contaminants mostly as a result of human activity, especially industrial activity. Contamination may affect water, soil and air and, from there, directly or indirectly reach food. While many possible contamination routes for heavy metals have become less and less important in recent years, environmental pollution and the potential transfer of contaminants to food is a matter that is more difficult to resolve, and can only be reduced to the extent to which industrial dumping is controlled.

Within the chapter of environmental contaminants of an organic nature, we will first deal with organohalogenated compounds, including dioxins and dibenzofurans, polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), and even organohalogenated pesticides (DDT, aldrin, dieldrin and others). We must remember that all these substances degrade with great difficulty and are therefore very persistent in the environment. All these compounds also have in common their high liposolubility,5 which explains their being substances that are very easily absorbed (through lipophilic membranes 6) and which, contrarily, are very hard to eliminate. In order to remove them from circulation, the organism accumulates them in adipose tissue.

Dioxins and benzofurans are always formed when there is combustion of chlorinated organic material or the presence of chlorine; for example, these products are usually formed in domestic and industrial waste incinerators. A significant source of these compounds is in polyvinyl chloride plastics (PVP), obtained by the polymerisation of vinyl chloride monomers. This type of plastic has long been questioned due to the possibility of vinyl chloride residues (known to cause cancer) migrating to food.

This migration is practically impossible given the quality demanded of plastics for food use, but their use has been banned in many countries due to problems deriving from the potential liberation of monomers, as well as to the production of dioxins and benzofurans when they are incinerated. These last two products are also by-products of obtaining organohalogenated pesticides.

Although their existence and growing toxicological importance as environmental contaminants cannot be denied, it is only fair to acknowledge that the relatively recent food scandal of the dioxin-poisoned Belgian chicken should not be considered an environmental pollution problem, but an accident, failure or negligence in preparing the chicken feed (contaminated with industrial -not food- oils) with which these animals were fed. In regard to polychlorinated biphenyls (PCBs), these are substances that currently pollute the environment due to wide industrial application in the past (electrical transformers, condensers, cooling systems...).

There are many routes to environmental pollution: destruction of refrigeration devices, dumps, etc., with accumulation mostly in sediments from sewage and at the bottom of stagnant water. Their high resistance to degradation and high bioaccumulation capability explains their presence today in the environment. The same can be said for DDTs and other organohalogenated pesticides that are highly persistent. Detecting them in foods, in many cases, is attributed less to their direct application to food, and their presence in the environment should be associated more with an extensive use in the past. The main dietary sources of all these contaminants are fats, oils and their by-products, milk and animal fat in general (meat, fish and eggs). All these halogenated compounds (especially chlorates), in addition to their great affinity for adipose tissue, can give rise to disorders of various types -neurological, dermatological (chloracne), immunological, hepatotoxic, etc.- but without doubt, one of the aspects that is cause for most concern is their possible role in causing cancer; in truth, they are more co-cancerous than cancerous.

The last group of this type of compound incorporated in the list of potential food contaminants consists of halomethanes. Specifically, the formation of these substances has been described in water in the course of making it potable. In the final analysis, the formation of these substances is caused by the combination of chlorine, introduced with chlorination, with short-chain hydrocarbons derived from the fermentation/rotting of organic material. Despite the fact that it is always a good idea to study alternatives for making water potable with less undesirable effects, chlorination should not be demonised because, were it not for chlorination, infections and toxi-infections (cholera, virosis...) due to water consumption would be multiplied.

Included among non-chlorinated organic contaminants are polycyclical aromatic hydrocarbons, the best known of which are benzopyrenes, which have been indicated as possibly having cancerous effects. These substances are formed by the combustion of organic matter, especially carbohydrates and lipids, at high temperature (300-500ºC). The components are normally part of smoke, either from the combustion of benzines or other petroleum derivatives, the controlled (smoking processes) or uncontrolled (fires) combustion of wood, or even cigarette smoke. These substances are also liposoluble and therefore easy to absorb and difficult to metabolise and eliminate.

Their presence in food has also been the object of recent scandal due to their detection in olive kernel oils. Nor was the presence of benzopyrenes in the environment in this case the cause of their accumulation in these oils, but it was due to bad practices in the technology treatment applied to obtain this type of oil. This bad practice, in fact, has been justified by some as an ecological measure to protect the environment since, compared with more traditional procedures, it gave rise to a lower amount of highly contaminating organic residues. In this case, as happened years ago with smoking processes, maximum legal tolerance levels have been established that must not be exceeded. In the case of oil, as in that of smoking, the problem was able to be resolved by means of adapting the technological treatments employed to obtain the oil.

On the down side, it is much more difficult to eliminate benzopyrenes that reach the environment due to industrial pollution, but also due to fires, even forest fires, with this exposure to man being more intense and continued than that suffered through food. This does not mean that this exposure should not be controlled and prevented or at least reduced by any means; rather the intent is to place the problem within the proper perspective in order to avoid the excessive alarm that is often caused amongst consumers as a result of these food safety subjects, the reactions to which tend to be more visceral than rational.

Benzopyrenes are not the only cancerous foods that may be present in the environment. Volatile nitrosamines are another example. Nitrosamines are formed by the combination of nitrous oxides with secondary amines. The nitrous oxides can come from combustion or be the result of bacterial activity on nitrates and nitrites. Another no less important source of nitrates in some rural areas, often very important in some parts of Catalonia, is liquid manure.

Free amines are very scarce naturally in food, but can accumulate by means of an enzyme amino acid-decarboxylase activity of bacterial origin, as happens in microbiologically deteriorated foods and in certain fermented products. Despite the fact that there may be a presence of nitrosamines in the environment, the greatest concern in regard to these compounds lies in their possible formation in the course of the technological treatment of food (smoking meats, making cold cuts, etc.).

Nitrosamines as well as benzopyrenes can be biotransformed in the organism into more toxic (cancerous) metabolites than they were originally, but this does not necessarily mean they will be truly cancerous. In other words, the human organism has defence mechanisms against these and other types of toxins and, therefore, exposure does not always mean there will be an effect. Whether there is or not depends on many factors, such as the dose and length of exposure, but also on many factors that depend on the individual, among which is increasing proof of the importance a good (nutritionally complete and balanced) diet has on defence mechanisms against xenobiotics in general.

Radionuclides (or radioactive elements) are another type of environmental contaminant that can get into food. As in the case of heavy metals, there is a certain amount of natural radiation, but it is never comparable to that derived from nuclear explosions (from civil or military facilities) or from impregnation in the environment due to the presence of radioactive waste (clinical/diagnostic, nuclear power plants, irradiation plants...). All radionuclides are toxic, if only because they are sources that emit radioactivity. However, many radioactive elements (plutonium, uranium...) are of less interest as food contaminants because they cannot be absorbed in the gastrointestinal tract. In these cases, the toxic effect is only on a local level.

The greater toxicological implication regards the radionuclides: with a long half-life (they take a long time to disintegrate), they can be absorbed by using the paths or mechanisms of nutritional mineral elements. Therefore, I131 (Iodine131) can compete with non-radioactive iodine in being captured by the thyroid; Cs137 (Caesium137) can become confused with potassium, interfering in all of its functions and Sr90 (Strontium90) can follow the route of calcium in regard to absorption as well as functions. Accidents like the one at Chernobyl or the use of atomic weapons (even if only in testing) strongly contribute to increasing the presence of radionuclides in the environment.

4. Protecting Consumers. "Food Safety" and the Risk/Benefit Balance

"Safety is a priority at every stage of the food chain from farm to fork".
"Food safety is a shared responsibility of everyone involved in the food chain from farm to fork".
(http://www.eufic.org)

Consumers are concerned with the safety or innocuousness of the food they eat, regardless of the origins of organisms or substances determining their potential toxicity, which are usually attributed to human activity (especially industrial activity) and not to natural toxicity. Along these lines, it bears repeating that many environmental contaminations have their more or less immediate or remote origins in human activity.

Since it is a concept that is highly employed currently, it seems appropriate to pinpoint what is meant by food safety. The United States Food Protection Committee defined, in 1959, the safety of food as "practical certainty that no damage or injury will derive from the use of a substance in the form or quantity proposed". The qualifier of "practical" applied to certainty, which means it is not "absolute", is essential. In fact, from a scientific point of view, no human activity is absolutely safe, which means having zero risk. Therefore, what is individually or collectively assumed in many cases, such as driving a car for example, is not in regard to food. This makes sense, because we introduce food into our organism; however, it should be assumed. That is why scientists must make constant efforts to transmit to society the meaning of the data available.

A first type of data, relative but significant, are those we could qualify as historical. The idea, which in fact is an ideal, that pollution of the environment and food is a relatively recent phenomenon in the history of humanity is not true. One only has to think of the condition of water consumed in drinking or preparing meals until it was made potable, or in irrigation waters, which even today are still quite polluted in many cases. Food that is absolutely uncontaminated has never existed. Furthermore, if we bear in mind all possible forms of pollution, our current diet is the least contaminated in history, among other reasons because the possibility of strict analytical control was practically nonexistent until well into the 19th century. The diet as a whole being the least contaminated does not mean that the current forms of industrial and agricultural production cannot cause much more massive and spectacular environmental pollution than before and that, in a few specific cases, it is not true that a certain food today is more contaminated than that of yesterday.

An extremely interesting consideration is that made by Egeland and Middaugh in December of 1997 in the prestigious journal Science. The authors, using very good criteria, criticized the tendency to reduce consumption of fish due to their potential content of certain derivatives of mercury (mainly methyl mercury), because this leads to a loss of the positive effects of eating fish. In fact, excessively strict criteria that are only based on not-duly-weighted safety precautions can make one forget the nutritional aspect (which is the fundamental reason for valuing food). Among the benefits derived from eating fish, especially oily fish, it is worth mentioning that they contribute polyunsaturated fats (omega-3) that help to reduce the risk of cardiovascular disorders.

They are also nutritionally appropriate due to their high protein content, low level of saturated fatty acids and because they are vehicles of antioxidants such as selenium and vitamin E. Furthermore, these same antioxidants can even contribute to protecting us from the negative effects of low doses of methyl mercury. In short, the value of food as a whole should be duly considered, not just the presence of contaminants (in doses that are not dangerous in themselves), in order to not make the mistake of doing without the positive properties of certain foods due to excessive concern over its safety. In the case of fish, and surely in many others, the positive impact is higher than the potential negative impact of a certain level of contamination. The reference to the dose of contamination is another key aspect in the concept of food safety.
This allusion to the quantity of toxins is, in truth, an unavoidable fact, because we do not live in an aseptic world, like an operating room.

The reasoning of Egeland and Middaugh is a proper application of the risk/benefit evaluation, which consists in globally considering the impact of food on the organism, by considering the positive as well as potentially negative effects. It is therefore best to eat fish, even tolerating a certain amount of contamination from derivatives of mercury, than to leave it out of our diet. Except, obviously, if contamination were truly significant from a toxicological point of view. As Paracelsus said in the 16th century, "The right dose differentiates a poison and a remedy". It goes without saying that this never means one should become "resigned" to pollution of the environment and food by organomercurial compounds, which in large part is due to industrial dumping that could be prevented or at least reduced. What needs to be emphasized is that, in this matter as well, "what is best is often inimical to what is good". It should also be added that currently, before authorizing any new product or substance that could mean a risk of exposure to human beings, assessment is made of its environmental impact, and not just of its use in the conditions that do not represent any risk to the environment and to any form of life, at least according to current knowledge.

In the final analysis, we often find ourselves before a problem of information and the credibility of this information. Consumer mistrust, often unjustified, but not always, is due, above all, to the fact that people believe they do not know or do not control what they consider to be risks or dangers, or they do not know or properly value the benefits of a product, as in the aforementioned case of fish.

The Universal Declaration of Human Rights acknowledges that all people have the right to sufficient, healthy food. That is why public administrations, and in Europe this begins with the European Union, must act to protect the health of consumers and monitor food safety. And they do. In a relatively recent response to all these concerns, the European Commission has started up in all member countries a Food Safety Campaign directed at consumers that places emphasis on the idea that, in order to achieve the objective of maximum food safety, an exercise in shared responsibility is required by all the links in the food chain: producers, transformers and distributors as well as consumers. The framework within which this activity is developed, and in which it in fact begins, is the environment, especially in regard to farmers, stockbreeders and fishermen.

Due especially to the recent spectacular cases of food contamination, the European Commission has drawn up and presented its "White Paper on Food Safety", in which it proposes the creation of a European Food Agency or European Food Authority, with the intent of increasing the quality levels of food products, applying strict labelling principles and improving controls and inspections. It seems that this Food Authority, which wants to be and must be "independent and transparent" will have as main functions the confirmation and communication of risks in the field of food, although risk management will remain under community and national institutions.

The headquarters for this organism has not been decided upon as yet, and Barcelona has presented itself as a very sound candidate to take this on. Spain has also created its corresponding Agency, and the same is being done in Catalonia. The criterion with which Catalonia is approaching it, according to information available to us today, is correct, because it would be under the Health department and would take on tasks that to date have been under the Department of Agriculture, Stockbreeding and Fishing and the Department of Trade and Industry, making it obvious that food safety is, above all, a health matter that, nevertheless, must be approached in an integral, coordinated way that includes the production sector (Agriculture and Stockbreeding) as well as the commercial sector (Trade and Industry).

In short, in regard to food contamination, we still have and surely will continue to have problems, because frauds and accidents are not 100% avoidable in any human activity. In any case, it can be stated that the foods we eat are reasonably safe, but we should not let our guard down. Along these lines, an essential step is conserving the environment in which food is produced. On the other hand, consumer confidence must be regained in order to prevent feelings such as the following:

Are you sure I can be sure when I'm assured that it is safe? (J.J. Francisco Polledo, La Vanguardia, 10 Dec. 2000).o

References

1 --Substances that are foreign to the organism.
2 --Properties that are perceived by sensory organs: color, smell, taste and texture.
3 --Micronutrients are the nutritional elements the organism requires in less quantity: above all vitamins and some minerals.
4 --The name of goitre is given to the disorder characterized by hyperplasia (growth) of the thyroid in response to a primary deficiency of iodine.
5 --Ability to be dissolved in fat.
6 --Having affinity for lipids or fats.

Bibliography

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• BELLO-GUTIERREZ, J.; GARCIA-JALON DE LA LAMA, M.I.; LÓPEZ DE CERAIN-SALSAMENDI, A. 2000. Fundamentos de seguridad alimentaria. Eunate Pub., 167 pages.
  
• CONSORCIO PARA LA SEGURIDAD ALIMENTARIA, 1999: Mitos y realidades de la seguridad alimentaria: 59 pages. Madrid.
  
• DANIELS, R.W. 1998: Home food safety. Food Technology, 52 (2): 54-56.
  
• EGELAND, G.M.; MIDDAUGH J.P. 1997. Balancing fish consumption benefits with mercury exposure. Science,278: 1904-1905.
  
• EUFIC (Consejo Europeo de información sobre alimentación). 1998. ¿Es fiable nuestra alimentación?. Foodtoday, 9: 1-4.
  
• FABRE, J.M.; BARALON, P. 2001. ¿Controlar desde el campo hasta la mesa?. Mundo científico, 222: 62-66.
  
• MARINE-FONT, A. 2000. Alimentación y riesgo: ¿podemos confiar en lo que comemos?. La Vanguardia, 10 Dec.
  
• MARINE, A.; VIDAL, M.C. 2001. Seguridad y riesgo de toxicidad de los alimentos. Arbor, 661.
  
• MARINE-FONT, A.; VIDAL-CAROU, M.C. 1996. Literatura y control alimentario. Alimentación, Nutrición y Salud, 3 (1):18-21.
  
• MORENO-GARCIA, B.; GARCIA-ARMESTO, M.R.; LOPEZ T.M., 2000. Riesgos sanitarios de la contaminación de alimentos. Alimentaria, January-February: 19-28.
  
• NARBONNE, J.F. 2001. Sobre la toxicidad de las dioxinas. Mundo científico, 222: 38-41.
  
• SCIAMA, Y. 2001. Metales pesados, ¿el reverso del reciclaje?. Mundo científico, 222: 78-80.
  
• SCIAMA, Y. 2001. ¿Cuánto mercurio ingerimos a diario?. Mundo científico, 222: 84-85.
  
• http://www.seguridadalimentaria.com
  
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• http://www.FoodSafety.gov/

Air Pollution and its Effects on Health
Jordi Sunyer i Deu
Unitat de Recerca Respiratoria i Ambiental (Respiratory and Environmental Research Unit)
Institut Municipal d'Investigació Mèdica. (Municipal Institute of Medical Research)

How does air quality affect human health? We now know that the greatest source of pollution is from motor vehicles, with data that is cause for concern in cities in southern Europe, such as Barcelona. The author goes over different epidemiological studies carried out in various parts of the world, which relate air pollution to exacerbation of pulmonary disease and heart failure. He also raises questions on the long-term relationship between pollution and its effects on health a few years later. Finally, he argues for greater efforts to be made to reduce air pollution in cities, particularly in the Mediterranean
area.

Is the air in our cities dirty? Following the severe episode of air pollution in London in 1952, plans for cleaning the air were begun which signified a noticeable reduction in the levels of air pollution in that city. In fact, in a recent article in The Economist (5 September 2001), Bjorn Lomborg presented the following figure on the levels of SO2 and black smoke in the city of London, concluding that the air of our cities is much cleaner now than it was in the past. Even though it is hard to guess how Lomborg may have obtained the concentrations of pollutants for past centuries (it wasn't until 1952 that measurements were taken), his argument could be valid in regard to sulphur compounds and black smoke. It is obvious that the substitution of carbon as a source of energy has led to a reduction of these pollutants, but limiting urban air pollution to just these compounds doesn't tell the whole truth.

Currently, the biggest source of pollution is motor vehicles, and these give rise to nitrogenated compounds and hydrocarbons, which, once oxidized, make above all nitrogen dioxide and ozone. By looking at the data obtained from the European ECRHS study, together with the European agency of WHO (Figures 2 and 3), we may observe that the levels of these pollutants have not only not decreased, rather in some cities, above all in regard to ozone, they have increased (Figure 3). Therefore, it is not true that the tendency is the same for all pollutants, and that this tendency is toward reduction.

In these graphs we may observe that the values of NO2 (an indicator of motor vehicle fumes) in Barcelona and other southern European cities double the values of northern European cities. This could be attributed to the places where air pollution measurement networks are installed if, for example, we were to place them beside busy roads and in northern Europe they were placed in the middle of parks. Nevertheless, a recent European study that used the same type of sensor and made measurement station facilities uniform found the same patterns in regard to fine particles (which also originate mostly from traffic). This means twice the pollution in our cities, and the same conclusion was reached in other European studies, such as the PEACE study or the EXPOLIS study.

Fine particles are one of the other pollutants that are currently on the increase, due to the increase in the number of diesel-powered cars on the road. This pollutant, as we will be analysing later, is of even greater significance than gaseous pollutants, due to its toxic properties. The levels of pollution due to fine particles (PM2.5) in Barcelona, as in other Mediterranean cities, are among the highest in the EU. An example is included here (Table 1) but any other example we might analyse (for example, the Aphea studies) would tell us the same thing.

So, in regard to weather and geographic comparisons, the air in Barcelona (as well as in most cities on the Iberian Peninsula studied in the EMECAM study) is relatively dirty. This statement makes the most sense when we analyse current knowledge of the effects of air pollution on health. The key question we will attempt to answer below is whether this level of pollution is dangerous to our health.

How Does Today's Urban Air Affect Our Health?

During the London fog incident in 1952, thousands of people died, the majority of whom were diagnosed with chronic bronchitis.1 This led to policies being established to reduce air pollution, but also to investigate its effects on health. In studies with groups of patients suffering from chronic obstructive respiratory disease in London during 1959-68, and in Chicago during 1968, an association was observed between daily increases in air pollution and intensification of the symptoms of chronic bronchitis. Before, in the 50s, investigators from the United Kingdom had proven not only that air pollution could aggravate the symptoms of chronic obstructive respiratory disease, but they also observed that the frequency (prevalence) of people suffering from chronic bronchitis and other forms of chronic obstructive respiratory disease was greater in postmen in areas with a high level of pollution than in postmen in other areas having a lower level of pollution. This was later confirmed in a study on the general population, not just postmen.2 Another study of postmen during the 60s observed that in addition to the symptoms, postmen working in areas with high air pollution had reduced levels of lung function.2

These English findings were reproduced in the United States and Poland. During the 60s in Holland, investigations were made to find whether or not physiological reduction of the Forced Expiratory Volume in the first second by repeated tests of lung function in the same individuals over time was greater in the more polluted areas. Living in areas with high levels of air pollution, regardless of whether the subject smoked or not, produced a quicker reduction in the volume of air breathed than that produced naturally by age. This predicted an advance in the age of developing clinical manifestations of obstructive respiratory disease. This all happened almost 30 years ago, and what interests us now is whether those findings are reproduced in recent studies.

Epidemiological Studies

The most common studies -those that have rekindled interest in the effects of air pollution due to the fact that, wherever they have been carried out, they have found positive results- are the so-called time series studies carried out during the decade of the 90s. These studies repeatedly showed that there is an increase in the number of deaths in the general population on days with the highest levels of air pollution, mainly with particulate pollution. This increase is observed above all in deaths where the cause was respiratory or cardiovascular. This increase is around 5% for each 10 mg/m3 of increase in particulate concentration. Among the most important studies, it is worth mentioning the multicentric studies such as the APHEA study in Europe3 and the MNAPS study in the USA.4

The APHEA study, (Air Pollution and Health; A European Approach) was undertaken in two stages. In the first, between 1994 and 1997, 15 European cities were included, Barcelona amongst them, and it was found that daily mortality was greater when the levels of particles of less than 10 mm (PM10) were increased, but also with elevations of other air pollution indicators such as sulphur dioxide (SO2), ozone (O3) and black smoke. The relationship between air pollution and mortality varied according to the season of the year, with a greater increase observed in warm seasons, which might indicate that in warm periods, the particles are more toxic. The new stage of the APHEA study incorporated 32 cities during the 1998-2000 period (13).

The findings were very similar to the previous findings in regard to the magnitude of the increase in the number of deaths in relation to a certain increase in pollution. But furthermore it was found that on days with more nitrogen dioxide (NO2), the association with particles is stronger, which suggests that the particles emitted by traffic are the most toxic. It was also seen that the association with the particles has a dose-response form that is almost linear, so that there is no zero threshold or safety level below which no effects are observed, and that the increase in effect is similar regardless of the level of pollution.
In the US, the MNAPS project, financed by the American energy industry, was carried out using more than 100 cities, in order to check the original findings of the group from Harvard University, which announced that the current levels of pollution were associated with an increase in mortality.

The findings from the MNAPS study are very similar to those of the European study. It is worth mentioning that the US has an extensive network of monitors of PM10, including PM2.5 and sulphates. The daily variations in the fine particle index (PM2.5, those attributed to traffic) were more intensely associated with the daily variations in cardio-respiratory mortality than with variations in the PM10 index. The dose-response ratio observed in the US study is very similar to that of the European study. In another recent US study, called the 6-city study, analysis was made of the association of mortality with daily variations in the different qualitative elements of fine particles. The greatest association with mortality was with lead, which the authors considered to be the best marker for traffic particles, while the particles from soil (Si) or the combustion of carbon by heating systems or industry (Se) were less associated with mortality. A study was carried out recently in Germany using a sophisticated mobile monitoring system to gather data on mass as well as numerical concentration of particles.

Researchers observed a greater relationship between the numerical concentration of ultrafine particles and the symptoms of respiratory frequency in a group of patients than with the concentration of mass (the usual measurement used in time series studies). This tells us that, in regard to particles, it is still unclear whether it is the quality or the quantity of particles that has toxic properties and, if so, which of the physical-chemical characteristics plays the most important role (mass or the number of particles).

Similar results were found in Australia, South America, China and Southeast Asia. The most important pollutants, according to these studies, are the particulate pollutants, yet the APHEA study also observed the important role of pollutants in the form of gas with sulphur dioxide (SO2) or ozone.

In addition to an increase in the number of deaths, the time series studies observed that on days with more pollution there were more patients admitted to hospitals who suffered from aggravation of their chronic obstructive respiratory disease, especially due to particles ; and of their asthma, due to particles5 and nitrogen dioxide (NO2).6 These findings were also reproduced in many other places.

Furthermore, recent years have shown that in many places the number of subjects admitted to casualty departments due to myocardial infarction is greater on days when the level of particles in the air is higher.7
In summary, short term (acute) exposure to particles and other pollutants has been associated with an increase in the daily percentage of admittance and death due to respiratory and cardiovascular failure in a multitude of studies from America, Europe and throughout the world. Detailed observation has been made of the association between inhaled particles and daily mortality, with the result of greater effect with fine particles (that have a greater ability to penetrate deeply into the bronchial tree) than with larger sized particles.

This acute effect has also been observed in follow-up studies of groups of patients (called panel studies) in which measurements are taken of the daily variations in respiratory symptomatology or of functional parameters, such as the values of lung function or the ST wave of the electrocardiogram, or cardiac rhythm or frequency, and are then related to the levels of pollution on preceding days. Consequently, there is great confidence in having the findings from the acute effects studies applied in general to any population that may not have been studied before, even though there may not be any detailed knowledge of the basic biological mechanisms.

Epidemiological Studies on the Chronic Effects of Air Pollution

Apart from the acute effect of air pollution on aggravation of pre-existing disease (such as chronic obstructive respiratory disease or coronary insufficiency) or causing death, an important question is to what extent is air pollution a risk factor in new cases of these diseases or a factor in reducing long-term life expectancy? That is, to what extent is there a long-term relationship between pollution and its effects on health over the years? 3 cohort prospective studies were carried out in the US8 on the relationship between environmental concentrations in the past and mortality of the general population.

These studies are: the study of 6 cities following a cohort of 8111 healthy adults from 1974-1977 until 1991 in 6 US cities (Boston, MA; Knoxville, TN; Portage, WI; St. Louis, MO; Steubenville, OH; Topeka, KS); the American Cancer Society (ACS) study that followed 552,138 adults from 151 areas from 1982 and over 7 years; and the "Adventist Health Study of Smog in California (AHSMOG)" which followed 6384 healthy non-smokers between 1977 and 1992. This last study attributed to each subject levels of exposure to air pollution using more than 350 measuring stations spread throughout the territory, and information on individual habits and features of each residence. All the studies observed that people who live in areas with more pollution are those at greater risk of dying due to cardio-respiratory causes, and that this increase is not due to tobacco, work or social class.

Particles are, again, the pollutant showing the most important association, especially fine particles. This means that the relationship between chronic exposure to air pollution and the risk of death increase linearly. It is worth mentioning that, in extending follow up of the participants to today in these studies, recently presented at the meeting of the International Society for Environmental Epidemiology (Garmish, 2001), there is also an increase in the risk of lung cancer in residents of the most polluted areas, regardless of whether they smoke or not. Higher mortality in more polluted areas could indicate either a greater prevalence of diseases related to pollution or greater severity of the disease itself in these areas than in less polluted areas.

Another type of study investigating the long-term effects is the disease-prevention study being carried out in several areas with different levels of pollution. These studies measure the prevalence of respiratory symptoms and the level of lung function. Until now, the most noteworthy studies are the AHSMOG study and the Swiss "Air Pollution and Lung Diseases in Adults (SAPALDIA)" study9 carried out over the years 1991-1993 on 5000 individuals. Both found a high prevalence of symptoms of bronchial hypersecretion, difficulty breathing or diagnoses of chronic bronchitis, emphysema or chronic obstructive respiratory disease in areas with higher levels of particulate pollution.

The SAPALDIA study also found that the levels of NO2 measured outside of each residence of the participants reduced lung function (in this case, measurement of exposure was individual for each participant and was not taken from the pollution network).

Only one study repeatedly evaluates in the subjects themselves the role of air pollution in reduced expiratory volume. The reduction in expiratory volume being greater than expected is a factor that is inherent to chronic obstructive respiratory disease, and is the mechanism by which tobacco produces this disease. The question is whether pollution can behave like tobacco and give rise to the same disease, regardless of tobacco use. The UCLA-CORD (The University of California at Los Angeles Chronic Obstructive Respiratory Disease) study monitored the changes in lung function over a period of time in several cohorts of smokers and non-smokers residing in areas of Southern California who were chronically exposed to different levels and types of air pollution.10 The 3 areas were Lancaster, with moderate levels of oxidants and a low level of particles; Glendora, with high levels of oxidants; and Long Beach, with a high level of particles, nitrogen oxides and sulphates. The residents selected (from 25 to 59 years of age) were examined twice, in 1973-78 and in 1978-82. Around 50% of individuals were re-examined (about 800 per area). Practically all the team and personnel doing the re-evaluation were the same as in the first test.

Reduction in the volume of air exhaled in men from Lancaster was lower than the average, as it was in Glendora, compared to Long Beach, the most polluted place, and this held true for smokers as well as non-smokers. Similar results were found with women who had never smoked. The authors concluded that pollution has a role similar to that of tobacco use. Even so, this study should be considered cautiously because it had significant limitations: the small number of areas studied and the low proportion of individuals re-evaluated.

Studies of lung function in children are very useful in understanding the chronic role of air pollution in the onset of respiratory disease in adults, because this indicates the potential effects on development of lung function. Lung function, as occurs with height, follows a path marked from the beginning, so that we can foresee the height or lung function that should be reached by following the values during early infancy. Reduction in maximum lung function reached during youth (starting at 20-25 years old, lung function begins a slow decline with age) can mean a reduction in life expectancy due to the onset of obstructive respiratory disease. Recently, three large studies were reported on the prevalence of lung function levels in the US and Canada,11with lower levels observed in the volume of air exhaled (indicator of lung function) in children residing in areas with high particle pollution. More interesting are the studies following the same children with repeated measurements of lung function over time, in order to evaluate how lung function grows in various places with different levels of air pollution.

12 The first of these prospective studies was carried out in 9 areas in Austria and 2 areas in Germany, selected according to exposure to ozone. For the 1,150 children, lung function was measured 6 times between 1994 and 1996. Children living in areas with the highest levels of ozone during the summer period as well as winter showed less growth in lung function, even when adjusting for the children's height and weight. The second study was conducted with adolescents in Krakow (Poland). Boys living in the most polluted area (due to particles and SO2) of the city had values of lung function that were higher at the beginning, but boys as well as girls in this area showed lower growth values for lung function than children living in less polluted areas after 2 years. In the third study, carried out in Southern California in 1993-1997 on school-age children, significant negative effects were found from particles, NO2 and inorganic acid aerosol in relation to lung function development. It is difficult to conclude from these studies that a certain pollutant is related to reduced development in lung function, due to the small number of areas studied, despite the fact that in the Austrian study, as well as in the one in California, an individual value of exposure to pollution was attributed to each child according to his or her activity and the type of street on which he or she lived.

Even so, it was not clear which pollutants were the ones involved, and it may be that all of them were pointing to the same source, which very likely would be traffic. These children, with development of their lung function being chipped away at, will be more at risk for developing obstructive types of lung diseases as adults.

Altogether, the epidemiological studies have consistently shown that the increase in air pollution can give rise to a rapid negative response, such as an increase in the number of deaths or hospital emergencies. The study of the long-term effects of pollution is much more recent, and only a small number of papers have been published. They all suggest that pollution has long-term effects, and certainly this impact would be even more relevant than the acute effect, yet there is a shortage of studies incorporating participants from a greater variety of areas and with more precise measurements being taken of the background of their exposure to air pollution.

Current Knowledge of the Patho-Physiological Mechanisms of the Effects of Air Pollution

The mechanisms by which a low level of particles can cause death or worsen cardiovascular or respiratory disease have not been determined, even though many hypotheses exist. A general mechanism would be produced by inflammatory intermediaries causing a cascade of physiological reactions that would directly or indirectly precipitate the cardiovascular effects.

Therefore, the main hypothesis in regard to the role of pollution is centred on the studies of laboratory animals and exposed healthy and ill volunteers in experimentation chambers. According to this hypothesis, fine particles have the ability to penetrate deep in the bronchial tree (crossing a long path of small bronchioles) and can deposit in the alveoli, the small sacs where oxygen and carbon monoxide are exchanged. In this site, particles cause damage (like an erosion) that would set off an inflammation at this level, which could cause a response from the entire organism.

This response could increase coagulability of the blood and intervene in the heart's basic functions. Furthermore, fine particles can enter the blood stream, being deposited in the heart, where they could produce a local inflammation in the heart muscle. Finally, particles as well as irritant gases (such as SO2, NO2 and ozone) could set off an inflammation in the bronchial wall, which could aggravate pre-existing respiratory diseases.

It is not known whether or not the content of particles is what determines their toxicity. Either the particles themselves or as carriers of other toxic components (such as gases or biological toxins and pollen) could be responsible. It is believed that transition metals (such as Fe, Cu, Ni, Co, Mn) have a greater relationship with effects, because they can cause the production of hydroxyl radicals, which are considered to be toxic to cells. Another hypothesis is that ultrafine particles are more toxic than larger particles because they settle in the alveolar region and can penetrate the pulmonary epithelia. Finally, it is possible that particles transport potentially toxic gases well into the lung, thereby increasing the risk of cell damage.

The gases studied most often are those coming from combustion, either primarily (CO, NO2) or secondarily (NO2, ozone).
A great deal of research exists on the effects of CO and the consequent formation of carboxyhaemoglobin, especially in patients with coronary insufficiency. For these patients, exposure to ambient CO worsens their coronary insufficiency in exercise tests. In several cities, hospital admissions due to cardiac problems have been associated with CO levels. Even so, the combined study of the effect of fine particles and CO shows that the association of particles is independent of and stronger than that of CO.

Ozone is a reactive gas that is not very soluble, which in high concentrations causes conjunctive irritation, cough, shortness of breath and transitory depression of lung function. In the bronchi, exposure to levels reached at ozone peaks in the summer in European cities causes hyperactivity and inflammation, which could mean an increase in respiratory symptomatology in asthmatics, something that has been proven in studies following groups of asthmatics through time. Nevertheless, the truth is that the ozone and other pollutants such as sulphates and acid aerosols increase together, and it is impossible to differentiate in epidemiological studies the individual role of each of them. Repeated exposure to high levels of ozone could cause a reduction in lung function, but these studies cannot differentiate the role of ozone from that of particles.

Nitrogen dioxide is a pollutant generated by combustion in vehicles, as well as cookers and gas heating, and is therefore found indoors as well as outdoors. It is a precursor to photochemical ozone generation. When inhaled, due to its not being very soluble, it can penetrate the smallest systems. It is less reactive than ozone, even though its toxicity mechanism may be different. In general, there is no agreement among different studies on the effects of NO2, even though the APHEA study proposed that it might strengthen the role of particles, which would coincide with the studies carried out in Canada.

Is It a Problem for Public Health Care?

A relevant question in regard to the impact of air pollution is if the effect on health described in the previous sections has any repercussions on potential reduction in life expectancy, or if it just slightly hastens death in people who are already ill and about to die. This effect of cutting short, called "reaping", could explain the increase in deaths in the seasonal series studies. Even so, in epidemic situations such as the 1952 London incident, there was no reduction in the number of deaths expected once the incident was over, like a negative rebound. On the contrary, that winter there was a noticeable increase in mortality, as if the pollution episode had had not just an acute effect, but also a medium-term effect.

This was also observed in Germany following the last pollution episode in December of 1985. Nevertheless, the reaping effect could not explain the mortality in the follow-up study of healthy people, or the increase in the prevalence of disease. So a likely scenario is that the acute effects of pollution are produced above all in people who are susceptible, because they already suffer from a base disorder such as a chronic obstructive respiratory disease, while chronic effects have an impact on healthy people.

This is what made Kuenzli13 recently conclude that traffic is responsible for more victims due to air pollution than due to road accidents. This leads one to believe that efforts to reduce urban air pollution must be stronger in order to prevent the onset of diseases or prevent existing diseases from worsening. Efforts made in Northern Europe have not seen corresponding efforts being made in our Mediterranean environment, where we suffer from the highest levels of pollution in the European Union. o

References

1 --Logan WPD. Mortality in the London fog incident. Lancet 1953; 1: 336-38.
2 --Lambert PM, Reid DD. Smoking, air pollution and bronchitis in Britain. Lancet 1970; 1: 853-57; Holand WN, Reid DD. The urban factor in chronic bronchitis. Lancet 1965; 1: 445-48.
3 --Katsouyanni K, Touloumi G, Spix C, et al. Short-term effects of ambient sulphur dioxide and particulate matter on mortality in 12 European cities: results from the APHEA project. Br Med J 1997; 314: 1658-63. Katsouyanni K, Touloumi G, Samoli E, Gryparis A, Le Tertre A, et al. Confounding and effect modification in the short-term effects of ambient particles on total mortality: results from 29 European cities within the APHEA project. Epidemiology 2001; 12:521-31.
4 --Samet JM, Dominici F, Curriero FC, Coursac I, Zeger SL. Fine particulate air pollution and mortality in 20 U.S. cities, 1987-1994. N Engl J Med. 2000 Dec 14;343(24):1798-9.
5 --Anderson HR, Spix C, Medina S, Schouten JP, Castellsagué J, Rossi G, et al. Air pollution and daily admissions for chronic obstructive pulmonary disease in 6 European cities: results from the APHEA project. Eur Respir J 1997; 10: 1064-1071.
6 --Sunyer J, Spix C, Quenel P, Ponce-de-Leon A, Ponka A, Barumandzadeh T, et al. Urban air pollution and emergency admissions for asthma in four European cities: the APHEA Project. Thorax. 1997;52:760-5.
7 --Peters A, Dockery DW, Muller JE, Mittleman MA. Increased particulate air pollution and the triggering of myocardial infarction. Circulation 2001;103(23):2810-5.
8 --Dockery DW, Pope CA, Xu X, Spengler JD, Ware JH, Fay ME, Ferris BG, Speizer FE. An association between air pollution and mortality in six US cities. N Eng J Med 1993;32:1753-9. Pope CA, Thun MJ, Namboodiri MM, Dockery DW, Evans JS, Speizer FE, Heath CW Jr. Particulate air pollution as a predictor of mortality in a prospective study of US adults. Am J Respir Crit Care Med 1995;151:669.74. Abbey DE, Nishino N, McDonell WF, Burchette RJ, Knutsen SF, Beeson WL, Yang JX. Long-term inhalable particles and other air pollutants related to mortality in non-smokers. Am J Respir Crit Care Med 1999; 159:372-82.
9 --Zemp E, Elsasser S, Schindler C, Kuenzli N, Perruchoud AP, Domenighetti G, Medici T, Ackermann-Liebrich U, Leuenberger P, Monn C, Bolognini G, Bongard JP, Brandli O, Karrer W, Keller R, Schoni MH, Tschopp JM, Villiger B, Zellweger JP, SAPALDIA team. Long-term ambient air pollution and respiratory symptoms in adults (SAPALDIA study). Am J Respir Crit Care Med 1999; 159:1257-66.
10 --Tashkin DP, Detels R, Simmons M, Liu H, Coulson AH, Sayre J, Rokaw S. The UCLA population studies of chronic obstructive respiratory disease: XI. Impact of air pollution and smoking on annual change in forced expiratory volume in one second. AmJ Respir Crit Care Med 1994;149:1209-17.
11 --Stern BR, Raizenne ME, Burnett RT, Jones L, Kearney J, Franklin CA. Air pollution and childhood respiratory health: exposure to sulfate and ozone in 10 Canadian rural communities. Environ Res 1994;66:125-42. Raizenne M, Neas LM, Damokosh AI, Dockery DW, Spengler JD, Koutrakis P, Ware JH, Speizer FE. Health effects of acid aerosols on North American children: pulmonary function. Environ Health perspect 1996;104:506-14. Peters JM, Avol E, Gauderman W, Linn WS, Navidi W, London SJ. A study of twelve southern California communities with different levels of air pollution and types of air pollution. II. Effects on lung function. Am J Respir Crit Care Med 1999;159:768-75.
12 -- Frisher T, Studnicka M, Gartner Ch, Tauber E, Horak F, Veiter A, et al. Lung function growth and ambient ozone. A three-year population study in school children. Am J Respir Crit Care Med 1999;160:390-6. Jedrychowski W Flak E, Mroz E. The adverse effect of low levels of ambient air pollutants on lung function growth in preadolescent children. Env Health Perspect 1999;107:669-74. Gauderman WJ, McConnell R, Gilliland F, et al. Association between air pollution and lung function growth in southern California children. Am J Respir Crit Care Med 2000;162:1383-90.
13 --Kuenzli N, et al. Public-health impact of outdoor and traffic-related air pollution: a European assessment. Lancet 2000; 356:795-801. Sunyer J, Schwartz J, Tobías A, Macfarlane D, Garcia J, Anto JM. Patients with chronic obstructive pulmonary disease are at increased risk of death associated with urban particle air pollution: a case-crossover analysis. Am J Epidemiol 2000, 151(1): 50-6.

Environmental Risks
Manolis Kogevinas, Josep M Antó and Jordi Sunyer
Unitat de Recerca Respiratoria i Ambiental (Respiratory and Environmental Research Unit)
Institut Municipal d'Investigació Mèdica (Municipal Institute of Medical Research)


The prestigious team of investigators at the Barcelona Municipal Institute of Medical Research reviews the latest research regarding the relationship between the environment and health. The article includes topics such as water pollution, pollution due to industrial waste, the atmosphere, the problem of dioxins, electromagnetic fields and mobile phones. In the last part, they include considerations on the concepts of risk management and the precautionary principle.

The impact of urban air pollution on health

The first international study evaluating the risk due to urban pollution was published in the year 2000.1 The study, conducted in Austria, France and Switzerland using the results contributed by studies of cohorts in the US and multicentric cross studies in Europe and California, estimates that 6% of mortality due to all causes could be due to air pollution, which would amount to about 40,000 deaths per year in these countries. Most of these deaths were attributed to particles and gas emitted by automotive vehicles. The authors also estimated the production of 25,000 new cases of chronic bronchitis and a total of half a million asthma attacks. The authors made a sensitivity analysis due to the uncertainty caused by the limitations of some of the observational studies included. The numbers provided are an average estimator in sensitivity analysis. If the estimates were true, this would have a greater impact than that due to road accidents.

These estimates may be transferred to Spain, keeping in mind the differences in population exposed to particles of less than 10 micra in our surroundings (the entire risk estimate was based on this pollution marker). The concentration of particles in Spanish cities participating in the APHEAII study (Barcelona, Bilbao, Madrid, Valencia) are above the average values of Paris in France and Basle in Switzerland, whereby we can assume that the Spanish population is at least as exposed as the populations of these countries to breathable particles, given that the majority of the Spanish population lives in cities. These differences, however, could be attributed to the placement of pollution sensors and to methods of measuring. Nevertheless, the ECRHS-II study is measuring the small-sized particles with the same sensor model and in just one laboratory, with the maximum possible uniformity in locating the sensor. Once again, and preliminarily, the data suggests that exposure of the Spanish population living in large cities is at least as high as that of Paris and Basle. That is why we believe it is reasonable to transfer these estimates to our environment.

A sensitivity analysis of the above estimates suggests that, according to the selected studies, these estimates could vary, above all in regard to the number of attributable deaths, but these estimates may even be conservative. This is even more contradictory when the estimate refers to potential years of life lost. If pollution only plays a role in advancing mortality in susceptible people, the number of potential years of life lost will be less than for road accidents, for example. However, the studies evaluated in the Kuenzli analysis measure the long-term effects. Furthermore, if one considers that pollution can increase the number of susceptible people, either due to its role in causing Chronic Obstructive Respiratory Disease or in coronary heart disease or even to the possible role of pollution in infant mortality, the estimates could be lower than reality.

At any rate, the uncertainty surrounding these estimates does not detract from the exercise carried out because: 1) there is a large body of knowledge backing the idea that the risk of air pollution is not zero; 2) decisions on air pollution control -especially traffic-related pollution- must be made now and with available knowledge, despite its limitations. In this way, the impact on the number of deaths attributable to air pollution makes sense in the context of setting priorities for primary prevention.

It is true that the new the EU Council Directive (1999/30/EC) will reduce the permitted limits of particle levels in the air of cities to values that are today much higher in many of our areas; however, without a clear will to reduce traffic pollution, we will never manage to get below the proposed value limit.

Quality of drinking water and effects on health

The appearance of two studies measuring the impact due to by-products from water chlorination has brought to light the relevance of this subject.2 Chlorination of drinking water generates trihalomethane and other by-products having mutagenizing, cancerous and spermatotoxic properties in experiments with animals. Human exposure to these compounds has been associated in epidemiological studies mainly with various types of cancer and adverse effects on newborns whose mothers were exposed.

Bladder cancer has been consistently associated with exposure to by-products of chlorination, with relative risks around 1.5-2.0 for exposure to trihalomethane over 75 mg/l for 35 years or more. For an average level of exposure to THM over an entire lifetime of 40 mg/l, the odds ratio is between 1.3 and 1.4. The results from studies of cancer of the colon and rectum, pancreas, oesophagus, breast and other types of cancer are not consistent.

The main reproductive effects investigated were miscarriage, low birth weight, retarded intrauterine growth, small birth size and neural tube defects. The six studies evaluating this effect found a positive association. The odds ratio varied between 1.18 and 4.0. Five studies investigated low birth weight associated with this exposure, with findings of an increase in risk. The odds ratio varied between 1.3 and 6.0. Small size for gestational age was evaluated by four studies, which found an odds ratio of 1.08 to 2.3. The risk of neural tube defects due to exposure to chlorination by-products was evaluated by four studies, finding odds ratios from 1.18 to 3.0.

Water chlorination can have various adverse effects on health. The most consistent evidence has been found for bladder cancer. Over the past few years, new findings have associated water chlorination with birth defects in newborns whose mothers were exposed. These effects have been associated with levels of trihalomethanes similar to those currently found in extensive areas of Spain.2 It is unquestionable that the disinfection of drinking water constitutes an essential and necessary step in making water potable. There are alternatives to traditional treatment with chlorine, which would mean lower generation of chlorinated by-products. It is necessary to carry out integral, rational management of the water cycle in order to allow the water quality to be at its most potable at the point of catchment. In developed countries such as Spain, disinfection and minimisation of chlorination by-products should not be considered antagonistic objectives.

Polychlorinated Biphenyls (PCB's) and neurobehavioral development and development of neurodegenerative disease

Exposure to lead or mercury at the beginning of life can affect neuroconductual development at critical periods, resulting in effects on sensory, cognitive or motor functions. This has led to interventions such as banning lead in gasoline. PCBs (polychlorinated biphenyls) used as solvents by industry and as insulation in electric transformers, as well as other persistent organic compounds (thus called due to their presence throughout the planet, their biostability and slow biodegradation, their accumulation in fatty tissue and their long average life span) can also be neurotoxic. PCBs are the most studied, due to two incidents of mass contamination. In 1968, more than 1000 people in Kyushu, Japan ingested oil contaminated with PCBs. Children exposed to PCBs in utero and via mother's milk manifested mental retardation.

In 1979, another accident occurred in Taiwan with cooking oil contaminated with PCBs and dibenzofurans, which caused retardation in neurobehavioral development in the children born during the period of intoxication. Several studies of numbers of newborns were conducted (Michigan, North Carolina and Oswego in the US, and Groningen and Dusseldorf in Europe) in order to evaluate possible effects of these compounds in populations exposed to the usual levels of the developed world. Altogether, the studies of series of newborns demonstrated a slight association between prenatal exposure to PCBs and motor development in the first years of life and cognitive development starting at one year of age.3

For the first time, the values of PCBs and other persistent organic compounds were determined in newborns in our area (Ribera de Ebro,4 Barcelona and Minorca). At the time of birth, all the newborns already showed detectable signs of HCB, DDE and PCBs in cord blood. The results showed that the levels of PCBs are somewhat lower than in the rest of Europe. However, the levels of DDE, DDT metabolite, and HCB (the second most common agent, after DDE, in our organism from among halogenated compounds) are double the rest of Europe, and up to 100 times those found in North America.5 This coincides with old studies conducted in the Community of Madrid on mother's milk and with the results of studies in adult populations. These compounds cross the placental barrier and it is estimated that nursing infants incorporate 20 percent more of them than adults, and that in the first 3 months of life, they can accumulate 6% of all that will be accumulated throughout the rest of their lives.

The effects of these pollutants in neurodegenerative diseases occurring in old age is unknown, but it has been suggested that small changes at the beginning of life in processes such as neurone connection and nervous system myelinization can signify large differences in the number of "active" neurone cells at the end of life, given the effect of decline in neurone contacts with age, which could mean that the small variations in points obtained in neurobehavioral tests at the beginning of life could be clinically significant in old age in diseases such as Parkinson's or dementia.

The recent incident of contamination of "Belgian chicken" with PCBs (and, to a lesser extent, dioxins) demonstrated that common ways of entry (beyond the episode that brought on the introduction of 50 Kg. of fats from transformers into the animal chain) are milk and meat. Research on this incident demonstrated the common practice of using fat from domestic waste dumps in preparing food for animals.6 This explains that the levels of PCBs and dioxins in food of animal origin are greater, in a high percentage of samples in "normal" situations, than recommended levels.4 It seems mandatory then to monitor levels of these pollutants in food products of the average diet in the EU, and in Spanish cities in particular.

Dioxins and health

Dioxins are a set of organochlorinated, lipophilic, bioaccumulative substances that persist in the environment. In humans, dioxins are metabolised and eliminated slowly. 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD) is the most toxic of the family of polychlorinated-dibenzo-para-dioxins (PCDDs). Dioxins are found ubiquitously in the ground, in sediments and in the air. The main sources of human exposure to dioxins in Spain and Western Europe are currently waste incinerators and metal recycling industries. Human exposure to dioxins is limited almost exclusively to diet (95% of total exposure), especially in milk and dairy products, in fish and in meat; that is, all types of food containing high proportions of lipids.

Excluding occupational and accidental exposure, most human exposure to dioxins is due to diet. TCDD is considered by the IARC (Cancer Evaluation Agency of the WHO) as a carcinogen for humans (in studies of workers exposed to dioxins, an increase was detected in mortality due to cancer of approximately 50%), although it has also been associated with other effects (epidemiological evidence in humans is currently conclusive only for dermatological effects and temporary increases in hepatic enzymes. There is also evidence of association with cardiovascular pathologies, diabetes and thyroid alterations in adults as well as children, although they are not definitive). Therefore, there is a growing concern regarding the effects in neurobehavioral and immune development in children due to exposure in utero and during nursing. Today, then, the dilemma is not whether dioxins are carcinogens or not, but rather the quantification of the risk of "lesser" disorders associated with exposure at a very low level in the general population.

In 1998, the WHO recommended that the intake of dioxins in adult humans should not exceed the limits of 1-4 pg/kg. weight/day. Currently, a significant proportion of the population of industrialised countries receives exposure above tolerable daily intake (TDI). Despite the fact that in past years levels of dioxins have decreased throughout Europe thanks to control measures, most populations in Europe are close to or above the limits recommended by the WHO. The scarce data existing on the level of exposure in Spain7 sets us among the countries with the highest exposure in Europe. In Spain, there is no population data of temporary tendencies, apart from a singular study on the population of Mataró (Catalonia). In this study (González et al 2001)6, which included 200 people from the general population who were monitored over a 4-year period (1995-1999), an increase was found in the levels of dioxin of approximately 13.5pg/g in 1995 to approximately 19.5 pg/g in 1999.

The reappearance of dioxins in the international press, when the Belgian contaminated food crisis broke, made manifest the serious deficiencies in controls on the food chains. In June 2001, the WHO and FAO reviewed the 1998 recommendation and proposed a "tolerable" limit for daily intake of dioxins of 70 picograms per kilogram of weight per month (approximately 2pg/kg/day). Therefore, a person weighing 70 kilograms can ingest over many years a total amount of 140 picograms of these compounds daily, without suffering any harmful effect. Despite the fact that these limits were expressed in relation to daily intake, they must be interpreted as limits of chronic intake, which should not be exceeded in a relatively long time. Small amounts of instantaneous exposure do not signify any increase in risk.

Very low frequency electromagnetic fields (EMF)

Electromagnetic fields are very low frequency waves (50-60 Hz) produced by electric devices and wiring.
The first study associating very low frequency electromagnetic fields with leukaemia in children was conducted in Denver, USA, in 1979 (Wertheimer and Leeper 1979). In the past 20 years, a multitude of studies have been conducted on very low frequency EMFs and their association with different diseases (leukaemia, brain cancer, breast cancer, testicular cancer, neurological diseases) in different populations (children and adults), different exposure environments (domestic or occupational) and using different designs (studies of simple correlation, studies of registration of mortality or incidents of cancer, case-control studies and cohort studies).

Occupational Studies. Numerous studies have been published on exposure at work, with results that have not been very consistent. Some of these studies included thousands of workers, such as, for example, the study on 13,800 workers (Savitz and Loomis 1995) at electric companies in the US, or another study of 223,292 workers in electric companies in France and Canada (Theriault et al 1994).

Apart from leukaemia and brain cancer, exposure to EMFs has also been associated with incidents of breast cancer in women and men. In some studies, an increase of risk was found (Pollan 2001), but on few occasions were other known risk factors that could have affected the results evaluated. Although some studies found an increase in the risk of cancer, all in all the results are not very consistent and rarely have they found a dose-response ratio.

Studies of Domestic Exposure in Adults. A study was conducted on exposure due to the presence of electric wiring, as well as wires from electric devices used in the home. Several epidemiological case-control-type studies have made precise evaluations of exposure. These studies focused on leukaemia and brain cancer.

Studies of Leukaemia in Children. The clearest evidence of a possible effect, and the most highly elaborated studies, are related to leukaemia in children. 21 studies were published in the US (5), Canada (2), Sweden (2), Denmark, the United Kingdom (3), Greece, Australia, Taiwan, New Zealand, Norway, Finland, Germany and Mexico. The methods used to evaluate exposure were different. At first, wire codes were used, and later studies used extensive measurements of EMFs in the children's current and previous homes. The risk estimate associated with leukaemia is variable. Few studies found statistically significant results (indicating that the results were not produced at random), and few evaluated and found a dose-response ratio, where this ratio is understood to be the tendency to increase the probability of developing the illness when exposure is increased. Nevertheless, in most jobs, increased risks were found (relative risk greater than 1).

In the year 2000, two independent analyses were published8,9 in which various studies published earlier were jointly evaluated. In the work of Ahlbom et al, the data from 9 studies was re-analysed (3203 children with leukaemia, 10,338 controls), while in the meta-analysis of Greenland et al, the data from 15 studies was analysed. Both teams found an increase in the risk of about 70%-100% in the category of subjects with the highest level of exposure, which corresponds with the study by Ahlbom of children exposed to average levels higher than 0.4 microteslas, and in the study by Greenland, at levels of 0.3 microteslas or higher. For lower exposure, no increase was found in the risk of leukaemia. Although thousands of children were included in both analyses, in the high-exposure categories, only a very low percentage was included which, in the case of Ahlbom's study, meant approximately 1% of the population.

The IARC recently (June 2001)10 evaluated the scientific evidence of the carcinogenicity of said EMFs. It concluded that the pooled control-case analyses indicate a relatively consistent association between childhood leukaemia and exposure to very low frequency EMFs of above 0.4 microtesla with risk increase of 2. This exposure is produced at a distance of less than a few dozen meters from high-voltage lines, with the exact distance depending on the line type and charge. It is improbable that this increase could be attributed to chance, but it could be biased, mainly due to a problem of bias in selection. As a consequence of this association, it was accepted as limited evidence of carcinogenicity of very low frequency EMFs, and these EMFs were classified as possibly cancerous to humans (group 2B). This is why recommendations are to avoid exposure such as locating schools, public services or housing near high-voltage lines.

Epidemiological studies on exposure to radiofrequency EMF (mobile phones)

The increase registered in the use of mobile phones and the new technologies of telecommunication via radiofrequency and microwave demands scientific evaluation of the possible effects of these EMFs on human health. Some social sectors demand objective information guaranteeing the safe use of these technologies.

Studies on People Who Use Mobile Phones

Risks of Road Accidents

Experimental psychology studies have clearly demonstrated that when several mental jobs are carried out simultaneously, execution of the tasks is worse than when these are carried out individually. The results of these studies indicate that when a driver talks on a mobile phone, his or her ability to react to potentially dangerous traffic situations is affected. This type of effect seems to be true regardless of whether the telephone is handheld or not. The most relevant study on this subject was conducted in the United States by Redelmeier and Tibshirani (1997). These authors showed that the risk of having an accident while using a mobile phone was 4 times higher than when it was not being used (relative risk 4.3; IC95% 3.0-6.5). Using a hands-free system offered no protection (RR of 5.9) in comparison with handheld mobile phones (RR of 3.9).

Epidemiology of Cancer and Other Serious Diseases11

Few studies have been conducted on the association of the use of mobile phones and morbidity (the onset of disease) or mortality. There is no epidemiological study on the effects of exposure to EMF at base stations.

The results were recently published of two exhaustive case-control studies on the use of mobile phones and brain cancer in adults and a cohort study in Denmark. The first study (Muscat et al 2000) evaluated a total of 469 people whose ages ranged between 18 and 80, with primary brain tumours, and 422 control subjects without this illness. The average monthly use was 2.5 hours for the cases and 2.2 for the control group. In comparison with people who had never used a mobile phone, the relative risk associated with regular use in the past or present was 0.85 (IC95% 0.6-1.2). The relative risk for those who used them frequently (>10.1 hrs/mo.) was 0.7 (IC95% 0.3-1.4). The relative risks were less than 1.0 for all histological types of brain cancer, except for neuroepithelioma, a very infrequent type of cancer (relative risk, 2.1; IC95%, 0.9-4.7). The authors concluded that " ...the use of mobile phones is not associated with a risk of brain cancer, but future studies should evaluate periods of exposure and/or longer latency…"

The second study (Inskip et al 2001) evaluated 782 patients with brain cancer and 799 control subjects (patients from the same hospitals without tumour illnesses). Compared to people who had never or very rarely used a mobile phone, those who had used them for more than 1000 hours in their lives showed relative risks of 0.9 for gliomas (IC95% 0.5 - 1.6), 0.7 for meningiomas (IC95% 0.3 - 1.7), 1.4 for acoustic neuromas (IC95% 0.6 - 3.5), and 1.0 for all types of brain tumours combined (IC95% 0.6 - 1.5). No evidence was found that risks were higher in people using mobile phones for 60 minutes or more per day or regularly for 5 years or more. The authors concluded that "...these results do not back the hypothesis that the use of mobile phones causes brain cancer, but the data is not sufficient to evaluate the risk in people using them frequently and over many years, nor to evaluate long latency periods…"

A nation-wide cohort study in Denmark of 420,095 mobile phone users between 1982 and 1995 (Johansen C et al 2001), observed that there had been no increase in the risk of brain tumours or tumours of the central nervous system, leukaemia or salivary glands.

Epidemiology of Other Illnesses in Mobile Phone Users

In a broad cross study conducted in Sweden and Norway, evaluations were made of the self-declared symptoms reflected in a questionnaire sent by mail to 11,000 mobile phone users (Mild et al, 1998). 13% of the Swedish participants and 30% of the Norwegians indicated that they had, at least, the symptoms of tiredness, headache, heat around the ear, which they themselves attributed to the use of mobile phones. However, given the methods used in this study and in a similar one conducted in Australia, it is very difficult to attribute these symptoms to RF EMFs.

Studies on People Living in Homes near Radio and Television Repeater Antennas.

The possible effects in health of exposure to RF EMF on workers and people who live near other types of antennas, such as TV transmitters, have been evaluated in several epidemiological studies, especially in relation to lymphomas, leukaemia, brain cancer and breast cancer. There are several reviews published on these studies (Elwood, 1999; Moulder et al, 1999; IEGMB, 2000). None of these studies evaluates exposure to EMF emitted by mobile phones or base stations. Most of these studies have significant methodological problems that limit their usefulness in evaluating potential adverse effects and, in any case, they only provide indirect evidence on the possible risks of mobile phones.

Conclusions from the Epidemiological Studies on Subjects Exposed to RF

The only harmful effect clearly associated with using mobile phones consists in a significant increase in the risk of having a road accident while using this equipment. There is currently no consistent epidemiological data providing indications that exposure to EMF of a wide range of RF is associated with the risk of developing any type of cancer. However, many studies conducted to date are not very informative and are limited in identifying light effects. This is why it is imperative to broaden research on the potential long-term or chronic effects stemming from intense or prolonged exposure to this type of non-ionising EMF.

Passive cigarette smoke during gestation12

The effects of cigarette smoke on gestation have been widely established: sudden infant death, respiratory illness during infancy or later onset of cancer. Over the past few years, research has been done on the habit of smoking cigarettes during pregnancy in most European countries, as part of the initiatives taken by health authorities to reduce the prevalence of this phenomenon. In our country, few studies have been conducted in this area. In 1996, rates for smoking cigarettes on a daily basis at 17 years of age in Barcelona showed a clear transition from men (24 %) to women (29 %). In the survey on health in Spain in 1997, these figures shot up to 43 % and 45 % in men and women, respectively, at 24 years of age. In fact, a recent study regarding the association between cotinine in cord serum and self-declarations of active and passive exposure to cigarette smoke revealed that 34 % of women smoked at the end of pregnancy in Barcelona,8 and another study in the same city found an infradeclaration rate for cigarette smoking among pregnant women who smoked.8 The particularly high prevalence of cigarette smoking in pregnant women, compared to the frequency in the rest of the European countries studied (England, Italy, Holland, Norway, Germany) is disquieting, because it may have unfavourable effects on the health of the new generations. That is why it is necessary to reduce cigarette smoking in women and, above all, prevent them from acquiring the habit of smoking.

Risk management: the precaution principle

In the above sections, we have concentrated on available knowledge on the existence and magnitude of risks. As we have seen, in many cases the available information is far from desirable, due as much to a lack of studies on key aspects as to the often-inherent limitations to research on humans. Even so, available information constitutes one of the bases for social action on risks through so-called risk management processes.

A recent matter that merits careful attention is the debate and specification of the use of the precautionary principle in managing environmental risks. Until now, risk management processes have been based on the principle that a certain factor or product was considered safe or acceptably safe until proven unsafe. This model, which has been adequate for a broad expansion of industry and commerce, carries with it intrinsically the fact that by the time the damage to humans from a certain pollutant can be proven, the accumulated damage in the human population tends to be considerable and have a strong foothold. Furthermore, it is not unusual to have the importance of possible economic and social consequences deriving from an action directed towards reducing exposure generate a significant conflict of interests that slows down policies of risk reduction, making them more difficult, if not downright impossible, to achieve. Obviously, the other side is that it minimises the possibility of acting against a risk unnecessarily.

Given this situation, many authors have proposed a change in focus based on adopting the precautionary principle.13 This principle establishes that, in the absence of sufficient scientific knowledge, a certain pollutant or environmental factor must not be considered safe for the environment and human health. The origins, characteristics and potentialities of this focus have been profoundly reviewed recently.14 However, in regard to risk management in our environment, what its truly worth pointing out is its adoption on the part of the EU Commission (EU02-02-2000). In this document, the Commission explicitly set the terms under which the precautionary principle must be used, emphasising that application of the precautionary principle must not exempt the risk in question from thorough scientific analysis. It must also mean a commitment to commissioning the research necessary to be able to make decisions based on sufficient scientific knowledge. It is well known that for certain environmental health problems such as that of mad cow disease, actions on the part of the Commission and most of the Member States were guided by the precautionary principle.

Although application of the precautionary principle in order to protect public health and the environment constitutes an area of maximum priority, its applicability is far from being resolved. Under these circumstances, its use should be accompanied by the utmost scientific, political and legal caution under penalty of being devalued due to improper application. Contrarily, research in methodologies facilitating implementation should be considered a priority.

References

1 --Kuenzli N, et al. Public-health impact of outdoor and traffic-related air pollution: A European assessment. Lancet 2000; 356:795-801.
2 --Villanueva CM, Kogevinas M, Grimalt JO. Drinking water chlorination and adverse health effects: Review of epidemiological studies. Med Clin (Barc). 2001 June 9;117(1):27-35. Villanueva C, Kogevinas M, Grimalt J. Chlorination of drinking water in Spain and bladder cancer Gac Sanit. 2001; 15(1): 48-53.
3 --Ribas-Fitó N, et al. PCBs and neurological development in children: A systematic review. J Epid com health 2001;55:537-46.
4 --Sala M, et al. Hexachlorobenzene and other organochlorinated compounds incorporation to newborns: Exposure across placenta. Chemosphere 2001;43:895-901.
5 --Porta M, Malats N, Jariod M, Grimalt JO, Rifa J, Carrato A, et al. Concentrations of organochlorine compounds and K-ras mutations in exocrine pancreatic cancer. PANKRAS II Study Group. Lancet. 1999 Dec 18-25;354(9196):2125-9.
6 --Larebeke N, et al. The Belgian PCB and dioxin incident of January-June 1999: Exposure data and potential impact on health. Env Health persp 2001;109:265-73.
7 --González CA, Kogevinas M, Gadea E, Pera G, Päpke O. Increase of dioxin blood levels over the last 4 years in the general population in Spain. Epidemiology 2001 May;12(3):365.
8 --Ahlbom A, Day N, Feychting M, Roman E, Skinner J, Dockerty J, Linet M, McBride M, Michaelis M, Olsen JH, Tynes T, Verkasalo PK. A pooled analysis of magnetic fields and childhood leukaemia. Br J Cancer 2000; 83(5):692-8.
9 --Greenland S, Sheppard A.R, Kaune W.T, et al. A pooled analysis of magnetic fields, wire codes, and childhood leukaemia. Epidemiology 2000; 11: 624-634.
10 --www.iarc.fr press releases: IARC finds limited evidence that residential magnetic fields increase risk of childhood leukaemia (27 June 2001)
11 --Elwood J M (1999). A critical review of epidemiologic studies of radiofrequency exposure and human cancers. Environ Health Perspect, 107, 155. Hansson Mild K, Oftedal G, Sandström M, Wilén J, Tynes T, Haugsdal B and Hauger E (1998). Comparison of symptoms experienced by users of analogue and digital mobile phones. A Swedish-Norwegian epidemiological study. Arbetslivsrapport 1998:23. Solna, Sweden, Arbetslivsinstitutet. Independent Expert Group on Mobile Phones - 2000. Mobile Phones and Health. Chairman Sir William Stewart. National Radiological Protection Board, Chilton, UK. Morgan R W, Kelsh M A, Zhao K, Exuzides A, Heringer S and Negrete W. Radiofrequency exposure and mortality from cancer of the brain and lymphatic/hematopoietic systems. Epidemiology, 11, 118. Moulder J E, Erdreich L S, Malyapa R S, Merritt J, Pickard W F and Vijayalaxmi D Z (1999). Cell phones and cancer: What is the evidence for a connection? Radiat Res, 151, 513. Muscat J, Malkin M, Thompson S, Shore R, Stellman S, McRee D, Neugut A, Wynder E. Handheld Cellular Telephone Use and Risk of Brain Cancer
12 --Pichini S, Basagaña X, Pacifici R, at al. Cord serum cotinine as a biomarker of foetal exposure to cigarette smoke at the end of pregnancy. Env. Health Persp. 2000; 108: 1079-1083. Castellanos ME, Muñoz MI, Nebot M et al. Validez del consumo declarado de tabaquismo en el embarazo. At Prim 2000; 26:629-632. Jane M, Nebot M, Badi M et al. Determinantes del abandono del hábito tabáquico durante el embarazo. Med Clin (Barc) 2000;114:132-135. Castellanos E, Nebot M. Embarazo y Tabaquismo: magnitud del problema y prevención desde los servicios sanitarios. Med Clin (Barc) 1998;111:670-674
13 --Foster KR, Vechia P, Repacholi MH, Science and the precautionary principle. Science 2000; 288:979-80.
14 --Protecting public health and the environment: Implementing the precautionary principle. Eds: Raffensperger ©, Tickner JA. Island Press 1999.

Alfons Calera earned degrees in Medicine and Surgery at the University of Valencia and is a senior technician in occupational risk prevention, specializing in Industrial Hygiene, Ergonomics and Psychology applied to prevention. He has worked as environmental quality technician for the Valencian government's Department of Health and Consumption as well as professor of environmental health.
From 1994 to 1998 he worked as senior technician in the Occupational and Environment Section of "Comisiones Obreras" (a Spanish Trade Union). He is currently the training section coordinator for the Trade Union Institute of Work, Environment and Health Salud (ISTAS), a section of "Comisiones Obreras".

What duties do you have in the Trade Union Institute of Work, Environment and Health?

The ISTAS is an autonomous technical-trade union foundation backed by the Trade Union Confederation of Comisiones Obreras (CC.OO.) for the purpose of promoting social development programmes to improve working conditions, protect the environment and promote worker health in Spain. It was started up in May 1996.

The purpose of the ISTAS is to offer support to union efforts in regard to occupational health and environmental protection.
The ISTAS maintains principles for action based on the autonomy and rigour that are innate to technical advice, as well as that of not interfering with the trade union decision-making process. As a trade union foundation, the ISTAS subordinates its orientation, planning and management to a Board of Trustees founded mostly by members of CC.OO. and designated by their Confederate Executive Committee.

What are its areas of activity?

Basically there are five: information, training, advice, research and communication. Regarding the first area, we have an information and documentation service to attend to inquiries on different aspects (technical, legal, trade union) related to occupational health and the environment.

In regard to training, we design training plans in order to improve the union representatives' capacity to intervene.
In the area of advice, we coordinate a territorial network of technical-trade union offices in order to advise the health and safety representatives and members of Committees on Health and Safety, as well as offering technical support to sector federations of the trade union.

In regard to research, we promote union-related lines with our own means and in collaboration with university agencies and others in the field of science.

In the area of communication, we make knowledge and information known, as well as promoting activities for social debate regarding the problems of occupational health and the environment.

What lines of research do you follow in occupational health and the environment?

They are many, and they are modified according to needs and projects. We do research in support of other actions -such as detecting needs or impacts in training matters- as well as promoting research in matters of special social interest, such as precariousness, toxin substitution or psychosocial risk factors.

I would like to mention the example of a project begun this year and which will continue for at least two more years, which is the analysis, evaluation and intervention in regard to chemical risk in the context of a sustainable future.
This project, which is being developed between the ISTAS areas of the Environment and Occupational Health and the BTS (European Trade Union Technical Bureau of Health and Safety).

Likewise, we have just finished completing publication on the Internet of our own database, which includes information on the use, limits and dangers to human health and the environment of about a thousand chemical substances. This can be accessed at the website http://www.istas.ccoo.es , trade union resource section, RISCTOX database. This database is complemented by the offer of information on cancerous substances.

The production, use, marketing and emission of chemical substances in our lives and into the environment makes manifest the strong ties existing among chemical risk in the workplace, public health and environmental pollution.

Existing policies of chemical risk have failed to prevent the general degradation of our health and the environment. These policies usually appear too late, they do not protect 100% of the population (so, for example, limit values are based on young men), they have offered only partial control and they have not solved the problem. Let us remember that what is controlled in the work place is emitted into the environment. Policies of chemical risk management have not been coherent or unified in the various areas of food safety, agriculture, public health, environment and occupational health.

The challenge of redirecting and unifying all legislation on chemical products towards a common strategy will be vital to building a sustainable Europe, because it requires practicing integration of social, environmental and economic criteria.

From an environmental point of view, what are the main health problems affecting Spanish workers? Which substances are the most problematic? Which sectors have the highest risks?

There are no indicators that allow us to precisely assert which main problems in occupational health stem from environmental exposure. However, by using indirect indicators, such as those offered by the "Fourth National Survey on Work Conditions" or by analysing the number and type of claims reaching our Occupational Health Technical Assistance and Advisory Service, we can state that the main environmental risk factors are light, noise, temperature, damp and pollutants.

Regarding the latter, we can state that professional illnesses recognized during the year 2000 in epigraphs related to chemical agents amounted to 2,860. 1

These indicators for damage to health only partially fill information requirements. In this sense, the "Fourth National Survey on Work Conditions" 2 offers us additional information. 27.7% of workers studied, or 3,227,272,3 are exposed to chemical pollutants due to inhalation of dust, smoke, steam, gas, etc. or due to handling harmful or toxic products. 17.1% of workers, about 2 million, handle harmful or toxic products in their jobs. Handling is more frequent in the industrial sector (27.1%) and, within this sector, in the chemicals branch.

19.7% of workers breathe harmful or toxic dust, smoke, gas or steam in their jobs. Inhalation is most frequent in the construction sector (35.7%), although the industrial sector (34.3%) is a close second. Within the industrial sector, the branch of manufacturing industries is the worst (45.5%).

Using the CAREX database on exposure to carcinogens amongst workers in Spain, we can identify substances, industries and workers exposed.
(see table)

Is there data on mortality due to professional cancer?

One of the most significant aspects of cancer is the long period of time that passes from the time we are exposed to these toxins until the first signs of the illness appear. This is what we call latency. Cancers caused by asbestos, such as pleural mesothelioma, can take as long as 25 to 40 years to appear following first exposure. Others, such as cancers of the blood, oscillate between 4 and 5 years.

We can attribute to professional cancer between 4 and 6% of total deaths due to cancer. This means that, in our country, around 4,000 to 6,000 workers die every year due to exposure to carcinogens on the job.

How is this type of information publicised?

A few months ago, we started up a system to register consultations managed in the field of occupational health at CC.OO. by 120 professionals. This system, which is not fully developed yet, includes information on certain aspects that are the reasons for consultation, basically on the part of health and safety representatives, with registration at the end of September reaching about 2,700 consultations.

Exposure to risk is the subject of most consultations, which means a third of the total received to date. Among these, exposure to chemical substances accounts for 1 in 5, taking second place, but close behind safety factors. Furthermore, chemical risk is present in the remaining interventions and consultations, because it impregnates the contents of damage to health, risk evaluation and health monitoring, etc.

Which are the most frequent types of consultation?

The products that are most frequently the subject of consultation are solvents, paints and dyes; resins, plastics and their components; elements related to specific processes in metallurgy, preservatives in the food industry and carcinogens in the processes of extracting non-metal crude and minerals, coking plants, oil refineries and gas production. Of special interest is the presence in all sectors and branches of products used in cleaning activities, which reveals risks related to exposure to bleach, ammonia, solvents, scale removers and other agents and mixtures.

Is there sufficient awareness among workers regarding health and safety?

In my opinion, there is never enough awareness, but in this field, we must place responsibility where it belongs. Employers are the only ones with the power to organize the production and choose the procedures, materials and qualifications they want. Therefore employers, personally or through their advisors on health and safety, are the ones who must possess the sufficient level of awareness to allow them to manage prevention with guarantees of safety for people and the environment.

Unfortunately, this is not so, as shown by the unstoppable growth in industrial accidents and industrial diseases.
Where workers do not possess sufficient prevention awareness, the responsibility of employers is to offer general and specific training on the risks to which their workers are subject.

References

1 --Register of Work Accidents and Professional Illnesses from the Ministry of Labour and Social Affairs. ATE-38-39-40. Epigraphs: professional illnesses produced by chemical agents, skin diseases produced by agents not included above, illness due to inhalation of substances and agents not included above and systemic illnesses. http://www.mtas.es/Estadísticas/anuario00/ATE/Index.html
2 -- IV National Survey on Work Conditions. Early results. National Institute of Safety and Hygiene in the Workplace. Ministry of Labour and Social Affairs. http://www.mtas.es/insht/statistics/enct_4.html
3 --EPA, fourth quarter 2000

European measures to protect man and the environment from dangerous substances and preparations
Ignasi Doñate
Lawyer specialised in environmental issues

1. Introduction

The international panorama following the terrorist attacks in New York has left public opinion scarred with the fear, amongst others, that the presence of anthrax spores is just one more battle in which bacteriological methods have been used to prolong the attack that began with the Twin Towers of the World Trade Centre. In just a matter of a few days, there has been news of moves in the USA to cultivate bacteria, and how there is a lack of safety and control over such activities; there is talk of stockpiles of materials for chemical warfare in countries of the ex-Soviet bloc and how Irak hid materials from the UN experts that would prove research work on chemical and bacteriological processes for wartime use was being carried out there; a link has been established between the Al-Qaida terrorists and methods to try and spray urban areas in the USA using a crop-dusting plane with chemical or bacteriological materials; and there is talk of the danger of atomic power stations being attacked with the resulting catastrophe of incalculable effects.

The widespread fear and precautionary measures that have been undertaken lead one to think of the possibility of attack with dangerous substances or products, only some of which have been developed or researched for wartime use, with many of them having been developed, handled and used in processes totally foreign to situations of armed conflict. It is paradoxical that, in this context, the danger can be seen from an objective perspective, a circumstance of which is the actual existence of dangerous products and substances, over and above the possibility, however remote, of their being used for destructive or wartime purposes.

The progressive increase in the use of dangerous substances in industrial processes, and inadequate processing in terms of their quality and quantity in the context of the trust given to new chemical products or preparations that are marketed as "revolutionary in their proved efficiency", has created the need to set up mechanisms for protecting the health of man and the environment. It is likely, however, that thought has never been given, nor protection measures put in place, to materially prevent the pharmaceutical, chemical and atomic complexes that exist at the present time from being used as powerful lethal weapons, especially against civil populations and their environmental surroundings.

2. Risk management in the context of war.

The current profile of the international conflict thus emphasises the importance of the high level of risk arising from the mere existence of dangerous substances, preparations and technology. I hereby recommend reading one again edition number 24 of the journal on "The Risk Society", which includes various articles that have little to do perhaps with the conflict at the present time but that take on a new and broader dimension in the light of current events. In the article by Narcís Mir i Soler, there is a quote by Ulrich Beck, part of which refers to the risk to current-day society in that "it is more than likely, under the pressure of the imminent danger, that there is a redefinition of responsibilities, that the powers of action become centralised and all of the details of the modernisation process are secured by bureaucratic controls and planning. As to a revolutionary society, the risk society is more a society of catastrophes where the state of emergency threatens to become the state of normality".

In spite of the impact caused by the extent of damage and the number of victims in the current conflict, one should remember the extent of industrial accidents like those at Chernobyl, Bhopal, Mexico City, and many others, where many of the effects of catastrophe have never seen the light of day, amongst other reasons because the more serious ones have occurred in poorer countries in the international ranking. As far as is known, there have even been more victims and damage as a result of these catastrophes than from chemical or bacteriological warfare although the number are low compared to what would occur if industrial installations in the developed world working with dangerous industrial substances or preparations were used. My mind goes back to the "The risk society" number of the journal although I will not go into what is the concept, magnitude and seriousness of environmental risk, the ways that this is evaluated, or risk control, as is formulated in the Council's current Directive 96/82/EC, dated 9 December 1996.

3.Regulations covering dangerous substances in Europe

The community directive mentioned above deals with the "inherent risks of serious accidents in which dangerous substances are involved". The title in itself leads "dangerous substances" to be considered as the original cause of the current risk society. This risk has not been considered as such, however, if one ponders the regulations on dangerous substances in Europe, which focus basically on the approximation of legislation protecting people's health and the environment of the different Member States and, as a result, to make trade possible within the confines of the Community.

This mercantile-protectionist approach to regulation in Europe began at the end of the sixties with Directive (Dir.) 67/548/EEC on the approximation of laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances. Even though regulations protecting people's health from these substances existed prior to this date, they had been laid down by each Member State and the diversity of regulations hampered trade of these substances and preparations within the European Community and, therefore, had a negative effect on the setting up and functioning of the common market. Thus, while the original regulations of the Member States aimed directly at protecting people's health, the focus of European regulations following the Community initiative in the sixties was to get round the obstacles to the internal trade of these substances and preparations.

On the basis of the approximation of relevant legislation of the Member States on dangerous substances, a regulatory process was begun within the context of Community jurisdiction that seeks to harmonise the different levels of protection of the Member States and reinforce the internal market. A framework of regulations has thus built up that, in short, influences the demands for safety that have arisen as the result of a violent confrontation on an international level that has come to the point of reaching unimaginable objectives.

4.- The generic system of protection.

The generic system of protection conferred by this framework of specific regulations is based on a series of processes directed at disseminating better and more reliable information on these dangerous substances. In specific terms, these processes are:

a) Notification by each Member State to the European Commission of the laws, regulations and administrative provisions on substances and preparations adopted internally.
b) Authorisation by each Member State of every substance prior to commercialisation, in accordance with an evaluation of its danger.
c) Mutual recognition of authorisations within the European Union.
d) Commercialisation according to the set of necessary conditions and requirements for substances and preparations to be placed on the market.
e) The Community list of substances and preparations that can be authorised by each Member State in accordance with their active ingredients, composition and formulation.

 

These processes are applicable to any substance or preparation that can be commercialised, which means the majority of them. A minority of substances and products are totally prohibited due to their dangerousness or the technological possibility of their being replaced by other less dangerous products.

These processes have succeeded in bringing about the single internal market although they have not improved the levels of collective safety owing to the fact that the increase in the use of dangerous substances and products over time has been greater than the need to limit or prohibit their use on the basis of new replacement technologies.

5. Classification, packaging and labelling of dangerous substances

The first in the framework of regulations to be put into place, as is mentioned above, was Dir. 67/548/EEC of 27 June 1967, on the classification, packaging and labelling of dangerous substances. This originated out of an awareness of the great complexity of the work that was just beginning: "Considering the wide scope of this field and the numerous measures necessary to bring about the approximation of all the provisions relating to dangerous substances, it would be wise to work firstly on harmonising the laws, regulations and administrative provisions on the classification, packaging and labelling of dangerous substances, and leave for subsequent directives the approximation of provisions on the use of these dangerous substances and preparations if it is confirmed that the differences between these provisions directly affect the setting up or functioning of the common market".

The control that the directive establishes over dangerous substances derives from the notification and ratification procedures between the different countries of the European Community concerning the substances appearing in the list of dangerous ones.

This Directive was subsequently modified and adapted to technological progress; the last modification was established by Dir. 2000/33/EC, which was the twenty- seventh adaptation of Dir. 67/548/EEC, directed at "limiting to the maximum experiments with animals, if other alternative methods exist". This directive came into effect in October 2001.

In broad outline, this directive enumerates the different characteristics qualifying substances as being dangerous. Annex 1 contains the list of dangerous substances and details the classification and labelling procedure for each substance. Annex III includes indications of the specific danger of each substance. Annex IV gives sound advisory information on each substance. Annex V establishes the methods for determining the physico-chemical properties, and the toxicity and ecotoxicity of substances and preparations. Annex VI gives a guide to classifying and labelling substances. Annex IX includes stipulations on safety locks for children.

The transposition of this regulation into Spanish law came into effect with the "Declaration of New Substances and the Classification, Packaging and Labelling of Dangerous Substances", a regulation adopted by Royal Decree (RD) 363/1995 on 10 March (BOE no. 133, dated 5/6/95) and subsequently modified at different times.

6. Limits to the commercialisation and use of dangerous substances and preparations.

Once the foundations had been laid to harmonise European laws on the dangerous substance list and criteria, a second regulatory process began with Directive 76/769/EEC of 27 July 1976 on "limits to the commercialisation and use of dangerous substances and preparations". The objective of the directive was, yet again, to restore, protect and improve the quality of human life while limiting trade in these products. The regulation appeared at a time when other directives and international agreements had already limited the commercialisation of certain substances and products and it was necessary to harmonise the laws of the Member States. This directive initially focussed on limiting the commercialisation and use of polychlorinated biphenyls (PCB) and polychlorinated therphenyls (PCT).
This directive was subsequently modified and adapted, as described below:

• Dir. 85/467/EEC, with further limitations and authorisation to the Member States to prohibit the use of PVC and PCT.
  
• Dir. 89/678/EEC, which authorised the Commission to adapt the basic directive to technological progress.
  
• Dir, 91/173/EEC, which limited the use of pentachlorophenol and its compounds.
  
• Dir. 91/338/EEC, which limited the use of cadmium and PVC as a colouring for cadmium.
  
• Dir. 91/339/EEC, which further limited the use of PVC and PCT, with the introduction of replacements.
  
• Dir. 94/27/EEC, which limited the use of nickel as a cause of sensitisation and allergies.
  
• Dir. 94/60/EEC, which limited the use of carcinogenic substances.
  
• Dir. 97/16/EEC, which limited the use of hexachloroethanes.
  
• Dir. 96/56/EC, which limited the use of carcinogenic substances.
  
• Dir. 91/659/EEC, which limited the use of asbestos as a cause of asbestosis, mesothelioma and lung cancer.
  
• Dir. 96/55/EC, which limited the use of chlorate solvents.
  
• Dir. 97/10/EEC, which limited the use of carcinogenic, mutagenic and toxic substances for reproduction.
  
• Dir. 1999/51/EEC, which limited the use of tin, PCF and cadmium.
  
• The last modification was brought about by Dir. 97/56/EC, and the last adaptation was introduced by Dir. 1999/77/EEC, which particularly dealt with stricter limitations on the commercialisation and use of asbestos due to its serious effects on the health of workers.

The transposition of this Community regulation into Spanish law came into effect with the RD 1406/1989 on 10 November and subsequent modifications and additions.

7. The classification, packaging and labelling of dangerous preparations.

A large third wave of regulations on dangerous products began with Dir. 88/379/EEC on the approximation of laws, regulations and administrative provisions of the Member States relating to the classification, packaging and labelling of dangerous substances. This directive and its subsequent modifications have recently been reinforced by Directive 1999/45/EC (OJEC no. L200 of 30 July 1999) to clarify the legal determinants of dangerous preparations.

This regulation is founded on the one set up by Dir. 67/548/EEC on substances, which it logically develops, especially everything referring to the classification and labelling of preparations that are dangerous to the environment. In this area, the directive revises the classification criteria for pesticide products initially established in Dir. 78/631/EEC and in the regulation on the commercialisation of pesticides. A large part of the directive was directed at improving the mechanisms informing about preparations placed on the market, improving the transparency of the information process and ensuring the high levels of protection in the labelling of preparations that were sought after by the regulation.

The directive opens up different ways for this improved level of protection to be complied with. On the one hand, it extends the requirements for information and labelling to preparations that were not initially classified as dangerous but which in use could be dangerous for the user, as in the case of explosives that are commercialised.

On a different level, improvements to the level of protection are enhanced through the addition to the labelling requirements of a two-fold information system: a) A safety data sheet intended for professional users, and b) the bodies appointed by the Member States which are responsible for the provision of information solely for medical purposes, both preventive and curative.

The categories of dangerous substances and preparations appear in the table below, in accordance with the text of section 2 of article 2 of the directive.

This regulation is not applicable to medicinal products for human or veterinary use; cosmetic products; mixtures of substances in the form of waste; foodstuffs; animal feeding stuffs; preparations containing radioactive substances and medical devices which are invasive or used in direct physical contact with the human body.

Dangerous substances and preparations

Explosives: explosive substances and preparations: solid, liquid, pasty or gelatinous substances and preparations which may also react exothermically without atmospheric oxygen thereby quickly evolving gases, and which, under defined test conditions, detonate, quickly deflagrate or upon heating explode when partially confined;
Oxidising substances and preparations: substances and preparations which give rise to a highly exothermic reaction in contact with other substances, particularly flammable substances;

Extremely flammable substances and preparations: liquid substances and preparations having an extremely low flash-point and a low boiling-point and gaseous substances and preparations which are flammable in contact with air at ambient temperature and pressure;

Highly flammable substances and preparations:

• substances and preparations which may become hot and finally catch fire in contact with air at ambient temperature without any application of energy, or
  
• solid substances and preparations which may readily catch fire after brief contact with a source of ignition and which continue to burn or to be consumed after removal of the source of ignition, or
  
• liquid substances and preparations having a very low flash-point, or
  
• substances and preparations which, in contact with water or damp air, evolve extremely flammable gases in dangerous quantities;

Flammable substances and preparations: liquid substances and preparations having a low flash-point;
Very toxic substances and preparations: substances and preparations which in very low quantities cause death or acute or chronic damage to health when inhaled, swallowed or absorbed via the skin;

Toxic substances and preparations: substances and preparations which in low quantities cause death or acute or chronic damage to health when inhaled, swallowed or absorbed via the skin;

Harmful substances and preparations: substances and preparations which may cause death or acute or chronic damage to health when inhaled, swallowed or absorbed via the skin;

Corrosive substances and preparations: substances and preparations which may, on contact with living tissues, destroy them;

Irritant substances and preparations: non-corrosive substances and preparations which, through immediate, prolonged or repeated contact with the skin or mucous membrane, may cause inflammation;

Sensitising substances and preparations: substances and preparations which, if they are inhaled or if they penetrate the skin, are capable of eliciting a reaction of hypersensitisation such that on further exposure to the substance of preparation, characteristic adverse effects are produced;

Carcinogenic substances and preparations: substances or preparations which, if they are inhaled or ingested or if they penetrate the skin, may induce cancer or increase its incidence;

Mutagenic substances and preparations: substances and preparations which, if they are inhaled or ingested or if they penetrate the skin, may induce heritable genetic defects or increase their incidence;

Substances and preparations which are toxic for reproduction: substances and preparations which, if they are inhaled or ingested or if they penetrate the skin, may produce, or increase the incidence of, non-heritable adverse effects in the progeny and/or an impairment of male or female reproductive functions or capacity;

Substances and preparations which are dangerous for the environment: substances and preparations which, were they to enter the environment, would or could present an immediate or delayed danger for one or more components of the environment.

The directive envisages different criteria of dangerousness based on physico-chemical properties (annex I), the danger to health (annex II) and danger to the environment (annex III).
Annex IV covers the particular provisions for packaging containing preparations intended for the general public. The particular provisions dealing with the labelling of certain preparations appear in annex V. The conditions for the confidentiality of the chemical identity of a substance appear in annex VI.

Lastly, Annex VII gives a list of repealed directives, together with the time limit for transposition and application of the directive, which should be made enforceable, in general, before 20 July 2002, except in the case of pesticides affected by Directives 91/414/EEC and 98/7/EC, the provisions of which must be applied before 30 July 2004. The directive is complemented by Dir. 91/155/EEC, which deals with the types of information system relating to dangerous preparations.

Spanish regulations in this area are contained in the Regulation on the classification, packaging and labelling of dangerous preparations, adopted by RD 1078/1993 on 2 July. This regulation was updated by the Order of 20 February 1995, partially modified by RD 363/1995 of 10 March (dangerous substances), with the latest modification adopted by RD 1425/1998 on 3 July (BOE no. 159, 4/7/1998).

8. The exportation and importation of chemical products in the European Union.

The regulations mentioned above only control the movement of dangerous substances and preparations with the European Community. The exportation and importation of dangerous products must be in accordance with international standards that regulate the world trade of these products.

At the present time, this matter is regulated by Regulation no. 2455/92 of 23 July 1992 (OJEC L251, 29/8/92). This regulation repeals the previous ones in force on this matter and introduces the international trade procedure for dangerous products known as "prior informed consent" (PIC), similar to the system established in the United Nations Environment Programme (UNEP) and the United Nations Food and Agriculture Organisation (FAO). At the same time, the regulation sets up a common Community notification and information system for importations originating in countries outside the EC.

In accordance with the PIC procedure and in order to protect the health of man and the environment, the international shipping of a prohibited or highly restricted chemical product is forbidden unless accompanied by the corresponding authorisation, in cases where this is compulsory, from the designated national authority in the importing country. This procedure is not applicable to products imported or exported for purposes of analysis, research or scientific development, or when it is not required in the importing country.

Annexes II and III of this regulation have been modified by Regulation 1492/96 and annex II has recently been modified by Regulation 2247/98, pursuant to the modifications carried out beforehand by the UNEP and FAO.

9. The commercialisation of pesticide products and biocides.

The notification or approval system generically established in Directive 67/458/EEC on dangerous substances is not applicable to the commercialisation of pesticides or biocides and these preparations are commercialised using specific procedures.

The commercialisation of pesticides (active substances and preparations used for protecting plants, improving the conservation of plant products, eradicating unsuitable plants and preventing inadequate plant growth) is regulated by Directive 91/414/EEC, which has been modified on various occasions.

Lastly, the commercialisation of biocidal products (active substances and preparations used for destroying, counteracting, neutralising, preventing the action or controlling any harmful organism by chemical or biological means) is regulated by the specific procedure set up in Directive 98/8/EC, of 18 February (OJEC no. L 123 of 24/4/98), which responds to the need for managing the risk associated with non-agricultural pesticides.

Spanish pesticide regulations are covered basically by Decree no. 3349/83, of 30 November (BOE no. 19 and 20, dated 23rd and 24/1/84), modified by RD no. 162, of 8 February (BOE no. 40, of 15/2/91) and RD 443/94 (BOE no. 76, of 30/3/94) in which reference is made to the commercialisation and use of pesticides.

10.Other substances, preparations and elements, installations, forms of transport, waste, etc. that make up the "risk society".

Within the context of the European regulatory framework, this article merely makes brief reference to the legislation that is usually indexed under the subject of "substances and products". Many other substances, elements and dangerous preparations have not even been considered, demonstrating the magnitude and fragility of an information, evaluation and control system based on the making of lists of substances and products that are obsolete almost by definition, as a result of the fact that technological developments and the placing of products on the market are always in advance of the ability to adequately control and legislate on dangerous substances.

In order to deal with the scope of dangers facing modern society, in terms of the formulation of a "risk society", other dangerous elements would need to be included, such as the wide range of medicines and drugs, pharmaceutical specialities, hospital products, food additives and other products that come into contact with foodstuffs, animal feedstuffs, detergents, fertilisers, cosmetics, radiation, transgenic products, biological agents, physical agents, etcetera.

Evaluating the level of risk means considering the impact of this long list of dangerous elements in every sector of activity. Complementary regulations, albeit basic in terms of safety, do exist in the sectors of dangerous transportation, hazardous waste, industrial installations, atomic energy installations and specific regulations protecting workers from all types of risk occurring in the workplace.

The extensiveness of risk in modern society means leaving aside any consideration of "civil protection" as an exclusive competency of the state and it becoming a competency shared together with suprastate bodies that must take on fundamental aspects of this protection work, especially through the international harmonisation of effective instruments for strengthening the safeguards against risks and the progressive replacement of dangerous elements with other alternative technologies.