Hormesis and ecological risk assessment: Fact or fantasy?

Abstract

Hormesis is a widespread phenomenon across occurring many taxa and chemicals, and, at the single species level, issues regarding the application of hormesis to human health and ecological risk assessment are similar. However, interpreting the significance of hormesis for even a single species in an ecological risk assessment can be complicated by competition with other species, predation effects, etc. In addition, ecological risk assessments may involve communities of hundreds or thousands of species as well as a range of ecological processes. Applying hormetic adjustments to threshold effect levels for chemicals derived from sensitivity distributions for a large number of species is impractical. For ecological risks, chemical stressors are frequently of lessor concern than physical stressors (e.g., habitat alteration) or biological stressors (e.g., introduced species), but the relevance of hormesis to non‐chemical stressors is unclear. Although ecological theories such as the intermediate disturbance hypothesis offer some intriguing similarities between chemical hormesis and hormetic‐like responses resulting from physical disturbances, mechanistic explanations are lacking. While further exploration of the relevance of hormesis to ecological risk assessment is desirable, it is unlikely that hormesis is a critical factor in most ecological risk assessments, given the magnitude of other uncertainties inherent in the process.

Key words:

• hormesis
• ecological risk assessment
• stressors
• risk management

Notes

Rosenstiel School of Marine and Atmospheric Science University of Miami Key Biscayne, FL, USA Phone: [phone] Fax: [phone] Email: [email protected]

National Center for Environmental Assessment‐Washington Office (8623‐D) U.S. Environmental Protection Agency Washington, DC, USA 20460 Phone: [phone] Fax [phone] Email: [email protected]