Preliminary definitions

Given that the precautionary principle is neither univocally understood nor interpreted, it may be useful to review the original meaning of a few words.

Danger is that which "threatens or compromises the safety or existence of a person or thing". Risk is "a more or less probable danger to which one is exposed" (Robert, Larousse). A risk may be potential or proven. This distinction is part of the approach that seeks to anticipate risks. The person who believes that the worst is bound to happen understands potential risk as a proven, immature risk, waiting to happen. This is not the case; it's primarily an approach based on probabilities. Admittedly, risks have a history, and many proven risks started out as potential, but many potential risks have never been proven. Finally, there is no such thing as zero proven risk, but a potential risk can be zero.