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The precautionary principle

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In France, the precautionary principle is defined since 2005 in one of the four texts of the Constitution of the French Republic, precisely in the Article 5 of the Environmental Charte:

“Where the occurrence of damage, although uncertain according to the state of scientific knowledge, could seriously and irreversibly affect the environment, public authorities shall, in accordance with the Precautionary Principle and within their fields of competence, ensure that risk assessment procedures are carried out and that provisional and proportionate measures are adopted to prevent the damage from occurring“.

This statement deserves some comments.

First of all, its original definition concerns the environment and not human health. The use has made that it is now in fact very often mentioned when talking about human health.

Asbestos as an illustration of the principles of prevention and precaution (see text). [Source: Gyrostat (CC-BY-SA 4.0), from Wikimedia Commons]
The word risk. A risk is the probability of being exposed to a hazard. In toxicology, danger is an intrinsic property of a chemical substance: without exposure, there is no risk. But there is no such thing as a zero risk: everything must therefore be done to lower and limit the risk, we cannot eliminate the “danger”. Eating fish in a reasonable way reduces the risk of exposure to methylmercury, a “dangerous” chemical compound.

The precautionary principle applies as soon as a set of indicators reveals a plausible risk with potentially serious consequences without yet having formal scientific evidence. The notion of risk uncertainties is essential to a proper understanding of this precautionary principle. For example, if this notion of “precaution” had existed in 1910, measures to limit the exposure of professionals to asbestos could have already been taken.

The precautionary principle is often mentioned instead of the prevention principle! Unfortunately, it is often the case that some politicians or health authorities confuse each other by using each other. The principle of prevention is used when the risk is known and proven; this is the most frequent case. Thus, since 1960, measures to prevent the risk of exposure to asbestos – the risk was proven – should have been taken; the use of asbestos has only been prohibited in France since January 1st, 1997.