Precautionary Principle and the Kehoe Principle


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


  • 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


  • 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.

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Critical Care


Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of three amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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