We are surrounded by risks but which of them should we take seriously?

If one wishes to minimize risks and, more importantly to be able to prioritize actions, it is necessary to know which risks are the most serious and which are perhaps not quite as important. It is possible to squander valuable resources in a manner that benefits health very little, if one cannot differentiate between what is important and what is not. There have been unfortunate cases of this in some policies of the European Union. EU bureaucrats and politicians have shown a knee-jerk reaction to pressure after some media exposure, in ill-advised attempts to demonstrate how concerned they are about the safety of the European public.

For example, media pressure was very crucial in mad cow disease and the Belgian dioxin feed scandal. In both cases, there had been a lack of responsible behaviour by some parties, but at the end of the day the health impacts were fortunately rather limited. The costs, however, were astronomical. At the same time, the EU has been unwilling to place stricter control on urban particulate air pollution which is estimated to kill hundreds of thousands of Europeans every year. The main difference is the lack of public and media pressure.

Priorities set in U.S.A. and by WHO

In 1992 a scientific committee of U.S. Environmental Protection Agency assessed the greatest environmental risks. According to this committee, these risks were due to the most important air pollutants, so-called criteria air pollutants (oxides of sulphur and nitrogen, ozone, carbon monoxide and particulate matter), toxic air pollutants (e.g. benzene), radon, indoor air quality, contamination of drinking water, occupational exposure to chemicals, occupational exposure to pesticides and ozone decrease in stratosphere. Climate change was listed as a major ecological risk, although it was not yet seen as a major health issue in 1992. Unfortunately this setting of priorities has not been very closely followed by EPA in its policies.

Within the context of the so called superfund legislation, EPA has been forced to set strict priorities, because enough funds are not available for removal and remedial actions at all sites contaminated by chemicals (NPL or National Priorities List). In some cases, the chemicals would, indeed, be best left alone and concentrating resources on preventing new contamination by enacting appropriate legislation.

In 2002, the environmental health report of World Health Organisation highlighted five important environmental health risks: unsafe drinking water and poor hygiene, air pollution, indoor smoke from solid fuels, lead exposure and climate change.

Country estimates of environmental factors

A few groups of researchers have tried to tackle the priority setting by scientific means. The Dutch National Institute of Public Health and the Environment has long been doing such studies. Their method is to use the Disability Adjusted Life Years (DALY) as the common denominator. This method attempts to sum up both years lost because of death and years partially or wholly lost due to diseases. Their estimate for the Netherlands is that the long-term effects of particulate air pollution account for more than half of the losses, but this estimate is relatively uncertain. Other important factors estimated were environmental noise, radon, UV-radiation, indoor air pollution including dampness in houses. The latter four factors and short-term exposure to air pollution were estimated to cause 2 to 5 percent of the disease burden. Addition of the more uncertain long-term particulate air pollution might increase the percentage, at most, up to 10%. These are clearly higher than the WHO estimates for developed regions. It was predicted that the environmental disease burden in the future (2010 to 2020) will probably decline.

In Finland, the Environmental Health Committee (1997) estimated that the most important environmental health risks were indoor microbes, allergens, radon and tobacco smoke, outdoor air pollutants, microbes in food and drinking water, accidents, noise, climate change and UV-radiation.

Clearly these evaluations have certain features in common, but there are also differences due to methodologies and local conditions. In many developed countries, drinking water is presently quite safe, even if there are occasional epidemics of diarrhoea. The indoor air has improved because of smoking restrictions recently legislated in many countries. On the other hand, indoor carbon monoxide causes a number of deaths when people are not aware of the risks of poisoning. Radon exposure varies from region to region. Lead in drinking water is a problem in countries using lead pipes, but not in other countries.

It is also noteworthy to consider what is not included in these estimates. Pesticides may cause real occupational risks in some countries, but to consumers, the risks are negligible and cannot be detected in the health statistics. There are very few individual chemicals with risks detectable in statistics; most of the major problems are mixtures such as smoke or air pollutants. The famous “dirty dozen” probably does not cause a single death now that the concentrations are so low. In global terms, microbiological risks are more important than chemical risks – for example unsafe drinking water and poor hygiene. With respect to radiation-induced cancer, natural UV-radiation and radon are responsible for most of the cancers, not man-made radiation.

Relative impact is important

It is very important to understand which risks are significant and which may not be so alarming. Even a small decrease in a large risk may mean more for the health of the population than even the complete removal of many little risks. Therefore it does not make any sense to direct all resources to a complex elucidation and control of these lesser risks, if more important risks exist.

Both in governments and environmental organisations, there seems to be a great deal of confusion and uncertainty about which risks are the most relevant. Often, the greatest emphasis is placed on exotic risks about which most people have virtually no knowledge or personal experience. On the contrary, much less attention is paid to commonplace risks attributable to traffic or energy production. It must also be admitted that scientific methods for comparing the risks are still not very good. Therefore it will be important in the future to concentrate on improving the methods by which we can scientifically conduct a realistic risk analysis.

The greatest payoff is possible and safety will be best enhanced when the society takes seriously the large common risks that are abatable. It is useful to remember what St. Matthew wrote: “Ye blind guides, which strain at a gnat, and swallow a camel.”

The large risks of environmental health are quite significant, and therefore it is important to set priorities in the right order and not waste precious resources trying to resolve only less important problems

Notes and references

One level up: Here a risk, there a risk, everywhere risks, risks!

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