An examination of the Environmental Protection Agency risk assessment principles and practices: a brief commentary on section 4.1.3 of the EPA March 2004 Staff Paper.

The US Environmental Protection Agency (EPA) recently issued a Staff Paper that articulates current risk assessment practices. In section 4.1.3, EPA states, "... effects that appear to be adaptive, non-adverse, or beneficial may not be mentioned." This statement may be perceived as precluding risk assessments based on non-default risk models, including the hormetic--or biphasic--dose-response model. This commentary examines several potential interpretations of this statement and the anticipated impact of ignoring hormesis, if present, in light of necessary conservatism for protecting human and environmental health, and the potential for employing alternative risk assessment approaches.