In This Article Expand or collapse the "in this article" section Precautionary Principle

  • Introduction
  • Definition
  • Overviews by Advocates
  • Position Statements of Prominent Organizations
  • Major Critiques
  • Activist Organizations
  • Economics Perspectives
  • Ethics Perspectives
  • Legal and Regulatory Perspectives
  • Political Perspectives
  • Perspectives on Public Participation in Decision Making
  • Risk Analysis Perspectives
  • Toxicology Perspectives

Public Health Precautionary Principle
Evelyn Alvarez, Yazmin Amado Vu, William M. London
  • LAST REVIEWED: 24 February 2021
  • LAST MODIFIED: 24 February 2021
  • DOI: 10.1093/obo/9780199756797-0046


Precautionary actions to protect health and ensure safety have always been an important part of public health practice. When hazards are well established with scientific evidence, precautionary action is most likely to receive consensus support. But when there are significant gaps in the scientific understanding of putative hazards, precautionary regulatory policies and recommendations to consumers are often controversial. Advocates for precautionary action against speculated threats have traditionally referred to commonsensical notions such as “better to be safe than sorry” and “better to err on the side of caution.” Since the 1970s, these notions have been codified into various formulations of the “precautionary principle” and have been invoked when scientific support is lacking as justifications for restricting specific technologies and requiring warnings. The precautionary principle has been applied to biotechnology, chemical pollutants, radiation exposure, food safety, medical technologies, occupational hazards, exposure to pathogenic organisms, and other public health concerns. International, national, local, and public health organizations have formally adopted frameworks for applying the precautionary principle. This article is an introductory guide to diverse formulations, analyses, applications, controversies, and implications of the precautionary principle relevant to public health practice. It is multidisciplinary with references to the literature of philosophy, ethics, law, economics, public policy, technology, risk analysis, toxicology, and other fields as well as public health.


A difficulty in studying the precautionary principle is that it has been formulated in a variety of ways with varying implications for when and how precautionary action should be implemented. No single formulation has been universally adopted. These references discuss influential statements that include definitions of the precautionary principle and analyses of various definitions. Gilbert 2020 provides a convenient overview. United Nations General Assembly 1992 offers one of the most frequently cited definitions. Sandin 1999 and Grandjean 2004 offer analyses of definitions combined with advocacy perspectives. Morris 2000 and Holdway 2009 offer analyses of definitions with an emphasis on difficulties for using them as a conceptual foundation for precautionary action. Persson 2016 suggests criteria to guide when the principle is applicable. The influential Wingspread Consensus Statement on the Precautionary Principle issued at the conclusion of the 1998 Wingspread Conference on the Precautionary Principle defined the principle as: “When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically” (from Science & Environmental Health Network, cited under Activist Organizations). Conceptual challenges to defending the precautionary principle as a decision rule were raised in Carter and Peterson 2015a. Steglich-Petersen 2015 offers a response to those challenges, and Carter and Peterson 2015b offers a rejoinder.

  • Carter, J. Adam, and Martin Peterson. 2015a. On the epistemology of the precautionary principle. Erkenntnis 80.1: 1–13.

    DOI: 10.1007/s10670-014-9609-x

    Raises two epistemological puzzles for defending the precautionary principle as a decision rule, one involving limitations in application of contextualism in epistemology, another involving the de minimis principle implying ignoring of farfetched risks. Calls for a nuanced formulation of the principle and bridging risk analysis with the theory of knowledge.

  • Carter, J. Adam, and Martin Peterson. 2015b. On the epistemology of the precautionary principle: Reply to Steglich-Petersen. Erkenntnis 81.2: 297–304.

    DOI: 10.1007/s10670-015-9740-3

    Responds to Steglich-Petersen’s solution to the authors’ two epistemological puzzles in defending the precautionary principle. Suggests that formulating, not merely applying the principle remains a puzzle and that the choice of method for computing probability of safety (or danger) is ad hoc because a good reason behind it is lacking.

  • Gilbert, Steven G. 2020. Precautionary principle. In Information resources in toxicology. Vol. 1, Background, resources, and tools. Edited by Philip Wexler, Steve Gilbert, Ashish Mohapatra, Sol Bobst, Antoinette Hayes, and Sara Humes, 489–494. London: Academic Press.

    Provides a concise overview of the history of the precautionary principle, including its origins in Germany, its usage around the world, and its endorsement by the US federal government when it signed and ratified the Rio Declaration of 1992. Concludes with a useful bibliography with some annotations.

  • Grandjean, Philippe. 2004. Implications of the precautionary principle for primary prevention and research. Annual Reviews Public Health 25:199–223.

    DOI: 10.1146/annurev.publhealth.25.050503.153941

    Traces the history of precautionary action and inaction in public health in response to suggestive, but unconfirmed, hazards. Discusses many aspects of the precautionary principle, including definition, critiques, statistical issues, and the future of precaution.

  • Holdway, Aaron. 2009. Reducing uncertainty: The need to clarify the key elements of the precautionary principle. Consilience: The Journal of Sustainable Development 1:37–54.

    Discusses shortcomings of definitions regarding level of threat that warrants action, level of evidence required to avoid taking precautionary action, range of actions to be taken, and level of force required of the actions.

  • Morris, Julian. 2000. Defining the precautionary principle. In Rethinking risk and the precautionary principle. Edited by Julian Morris, 1–21. Oxford: Butterworth-Heinemann.

    Historical overview of the precautionary principle and critique of a range of definitions. Characterizes the precautionary principle as “Pascal’s wager of the environment” and unnecessary. Argues that it leads to disingenuous demands for reversing the burden of proof and calls for overly broad duties to action that would hinder health-enhancing technological development.

  • Persson, Erik. 2016. What are the core ideas behind the precautionary principle? Science of the Total Environment 557–558: 134–141.

    Overview paper suggests circumstances justifying extra precautionary action are systematically underestimated values; threats of irreversible, irreplaceable, severe effects; timely response is at least as important as being right; and avoiding false negatives is more important than avoiding false positives.

  • Sandin, Per. 1999. Dimensions of the precautionary principle. Human and Ecological Risk Assessment 5.5: 889–907.

    DOI: 10.1080/10807039991289185

    Compilation and analysis of definitions given by seventeen different agencies. Notes how definitions vary in precision and strength but includes as components threat, uncertainty, action, and mandate.

  • Steglich-Petersen, Asbjørn. 2015. The epistemology of the precautionary principle: Two puzzles resolved. Erkenntnis 80.5: 1013–1021.

    DOI: 10.1007/s10670-014-9694-x

    Claims to resolve the epistemological puzzles in Carter and Peterson 2015a for defending the precautionary principle. Argues that adjudicating between relevant interests in threat assessment is normal in applying the precautionary principle in policymaking and that Carter and Peterson mistakenly dismissed a method for computing the probability of safety as ad hoc.

  • United Nations General Assembly. 1992. Report of the United Nations Conference on Environment and Development, Annex I, Rio Declaration on Environment and Development, Rio de Janeiro, 3–14 June 1992.

    Principle 15 defines the precautionary approach as: Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.

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