• precautionary principle
• risk factors
• public health
• regulations

“As to diseases, make a habit of two things—to help, or at least do no harm” (Hippocrates, The Epidemics)

“When an activity raises threats of harm to human health . . ., precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically” (Wingspread conference, 1998)

A fundamental teaching in clinical medicine is primum non nocere—first do no harm—that is, when physicians face choices between uncertain benefits and possible harm, they must err on the side of safety.

In environmental public health a similar edict has emerged. The “precautionary principle”, popularized 10 years ago in relation to environmental safety,¹ is now increasingly accepted. It asserts that when there is suspected harm and the scientific evidence is inconclusive, the prescribed course is precautionary action. It is intended to apply when the harm is “serious, irreversible, and cumulative”. The precautionary principle is the flip side of “risk assessment”—the current coin of the realm—which requires safety advocates to provide convincing evidence for harm. By implication, if they fail to do so, possibly dangerous products or practices will remain in place.

A popular summary of the principle arose from a UN conference and is found in the 1992 Rio Declaration: “Nations shall use the precautionary principle to protect the environment. Where there are threats of serious or irreversible damage, scientific uncertainty shall not be used to postpone cost-effective measures to prevent environmental degradation”.¹

The principle initially applied only to toxic substances but has since broadened to include other environmental hazards. It struck me that there is no reason why it should not be extended further to include much of injury prevention. Because I dislike clichés like “paradigm shift” in this case I am …