Temps de lecture :5 minutes
According to the WHO, the World Health Organisation, almost 23% of deaths have environmental causes; 36 % for children under 14 years old (1). The environmental risk factors play an important part in almost 80% of illnesses.
In developing countries, this mainly corresponds to problems linked to insalubrity and transmissible diseases. Indeed, malaria and diarrhoeal illnesses (like cholera) alone kill several million people every year. But the number of mosquitoes which spread the first disease can be reduced through sanitation and environmental measures and risks of the second can be considerably reduced by appropriate access to drinking water. According to the WHO, over 40% of deaths linked to malaria and about 94% of deaths caused by diarrhoeal illnesses could be avoided by better environmental management in less developed regions. (4)
In the North, these problems are non-existent, or they do not, at least, pose much of a problem. The environmental health risks therefore come from harmful molecules generated by industrial processes. Such problems also occur in the South.
Apart from industrial disasters, there are low doses of pollutants in the environment. But as the populations which are exposed are large and they are exposed to the harmful substances for a long time, there can be very serious health repercussions. However, their precise responsibility for pathologies (causality) is hard to determine. It requires very long (over several years) epidemiological studies on very large population samples (sometimes hundreds of thousands of people). It is therefore very expensive. The results are often controversial, as in the case of electromagnetic waves from high-voltage power lines or mobile telephone aerials, to name but a few [see Health and Environment debate]. Even if scientific research often treads cautiously, the lack of evidence of danger does not necessarily mean that there is no danger.
Moreover, it seems that the biological mechanisms at work for small doses and more concentrated doses are different. Whilst it is generally considered that there is a threshold below which the effect is negligible, certain molecules, cancerous ones in particular, seem to act regardless of concentration. (5)
It is then generally considered that cause and effect are proportional: the more the substance is harmful, the more it is dangerous. But in some cases, the effect is stronger at lower levels. Conversely, in other cases, a microdose rather has a protective effect – this is called radiation hormesis or radiation homeostasis.
Another layer of complexity to this subject is that the effects of different molecules are sometimes combined when they are in the same organism. And lastly, that certain products called « persistent toxic chemicals » because they do not break down, or break down very little, increase progressively as one goes up the food chain. Even though they can be found in small amounts in the environment, they can be very concentrated in some top predators – this is the case of certain marine mammals contaminated by PCBs in the Arctic, for example.
100 000 substances
The cases and the molecules are extremely varied: lasting heavy metals and pesticides in food, lasting radiation, various cancerous elements – some, like cigarettes, which are sometimes consumed willingly – pharmaceutical residue which alters the reproductive system, various allergens… This variety is proportional to the variety of molecules produced by our modern industrial environment. However, there are now about 1000 000 chemical substances on the market. In 1930, the world produced 1 million tons of chemical substances. Today, this has gone up to 400 million tons today. (5) These substances can be combined or transformed – through combustion for example – to produce other unknown or lesser-known substances. Evaluating the risk they present is therefore particularly difficult.
Asbestos – a classic case
Asbestos is an important example of a lobby’s negative effects. Considering its remarkable properties (insulation, fireproofing, etc.) and its low cost, asbestos was widely used throughout the world. However, it is cancerous. The first alarms were raised at the beginning of the XXth century and after the war, numerous studies showed how dangerous it was. For a long time, asbestos producers managed to prevent any coercive steps. Thus in France, the first decree, which was not very restrictive, dates back to 1977. Asbestos was only banned in 1997. Today, several thousands of people die from asbestos poisoning every year, and this should continue for the next 20 to 25 years, because of mesothelioma’s (the lung cancer caused by the molecule) latency period. The International Labour Organization (ILO) estimates that 100 000 people will die in the world every year until 2030 because of how asbestos was, or is still used. Indeed, only 40 countries, including the 25 European Union countries, have banned asbestos. (6)
Health and environmental regulation varies enormously from one country to the next. Certain very dangerous products are banned but for others, the authorities generally try to put in place regulations based on thresholds – despite all the limits of proceeding in such a manner.
In the case of mercury in tuna and swordfish, for example, the experts tried to estimate the maximum amount that could be absorbed. This amount should not be exceeded (the tolerable weekly intake is about 300 micrograms for an adult). They then estimated how much of the product was absorbed on average (300 grams of fish a week per person, for example) and they set an average amount that should not be exceeded (set at 1 milligram per kilo of fresh fish by the European Union in 2005). The problem is obviously that certain people are more sensitive than others, such as children and pregnant women. Some people are also more exposed, in this case, those who eat more fish. Moreover, pressure from industrialists or consumers influences decisions and can often explain regulation differences between neighbouring countries.
In 2007, the European Community Regulation REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) took effect: it is an important step towards regulating chemical product production and health and environment protection.
Dichlorodiphenyltrichloroethane, commonly referred to as DDT, is another important example. This insecticide was used very widely from the Second World War onwards to fight disease-causing insects (cholera and typhoid, for example) and as a pesticide on crops. However, it is cancerous. This was revealed to the public in 1962 by the American biologist Rachel Carlson in her book, Silent Spring. The work, which has become a reference in environmental history, sparked worldwide uproar and brought about the product’s ban in many countries.
However, in 2004, during the Stockholm Convention on Persistent Organic Pollutants (POPs), the countries most affected by malaria were granted permission to use it in the name of pragmatism: the parasite carried by mosquitoes cause more damage than the pollutants. This decision, which was fiercely criticised, shows how difficult it can be to make certain practical choices.
2. Ministère de l’Ecologie français – fiche santé et environnement
3. Dominique Belpomme, « Ces maladies crées par l’homme », Albin Michel, 2004.
5. Peut-on contrôler la pollution ? Teddy GOLDSMITH, L’Ecologiste n°18, mars-avril-mai
6. Le drame de l’amiante en France : comprendre, mieux réparer, en tirer des leçons pour l’avenir (rapport)
7. Silent Spring, Penguin, réédition, août 2006