Precautionary Principle and the Kehoe Principle

OVERVIEW

• The Precautionary Principle and Kehoe Principle reflect different conceptions of risk in the absence of evidence

THE KEHOE PRINCIPLE

• The ‘Kehoe Principle’ is a commonly made misconception summarised as:

The absence of evidence of risk = Evidence of the absence of risk

• Robert A. Kehoe was a toxicologist employed by the Ethyl Corporation in the 1920s
• He exemplified the ‘show me the data‘ mentality in defending the safety of leaded petrol
• His stance was based on the rationale that there was no convincing published evidence of harm to humans
• Subsequent research demonstrating harm led to the complete removal of lead from gasoline in the United States by 1986

PRECAUTIONARY PRINCIPLE

• This is a safer, more rational approach to think about risk in the absence of evidence:

The absence of evidence of risk = a possibility of risk until proven otherwise

• use of the precautionary principle puts the burden of proof on those that claim an action does not cause harm
• however, it is not a useful decision-making principle on it’s own — any course of action needs to weight the benefits and risks — and all claims (whether for benefit or risk) carry a burden of proof

References and Links

Journal articles

• Nriagu JO. Clair Patterson and Robert Kehoe’s paradigm of “show me the data” on environmental lead poisoning. Environ Res. 1998 Aug;78(2):71-8. PMID: 9719610.
• Peterson M. The precautionary principle should not be used as a basis for decision-making. Talking point on the precautionary principle. EMBO Rep. 2007 Apr;8(4):305-8. PMC1852769.