Hormesis: Policy implications

Protecting workers and the public from toxic chemicals, particularly carcin ogens, has been a principal focus of public policy. Uncertainty regarding t he toxicity of particular chemicals and their dose-response relationship ha s led to the use of the 'precautionary principle' in which regulators are w illing to accept more costly regulation than necessary in order to prevent exposure and disease from these toxic chemicals. The Environmental Protecti on Agency's (EPA'S) current policy of using 'mechanism of action' to set re gulations means that hormesis could be used by the EPA without any change i n policy if hormesis is accepted as scientifically valid. Hormesis could re sult in a qualitative change in regulatory policy. Because exposure to toxi c chemicals conveys no health benefit in the current dose-response model, p ublic risk aversion leads to a Delaney Clause-like 'no-risk' model for poli cy: ban toxic chemicals or lower exposure to trivial levels, Hormesis impli es that individuals benefit from low exposure to toxicants, Although hormes is may not be relevant for individuals with compromised immune systems, it would be expected to help the vast majority of people. If so, permitting ex posure levels that provided the greatest health benefit to most people woul d be balanced against these same levels hurting the most immune-compromised individuals. Public health routinely makes these trade-offs using a 'risk- risk' model. Thus, hormesis could transform the 'no-risk' approach into a ' risk-risk' approach that could tolerate much higher exposures to toxic chem icals than the current policy. Copyright (C) 2000 John Wiley & Sons, Ltd.