Send to

Choose Destination
Hum Exp Toxicol. 2002 Feb;21(2):91-7.

Defining hormesis.

Author information

Environmental Health Sciences, University of Massachusetts, Amherst 01003, USA.


Much confusion surrounds the concept of hormesis and what its biological meaning represents. This paper provides a definition of hormesis that addresses its historical foundations, quantitative features, and underlying evolutionary and toxicologically based mechanistic strategies. Hormesis should be considered an adaptive response characterized by biphasic dose responses of generally similar quantitative features with respect to amplitude and range of the stimulatory response that are either directly induced or the result of compensatory biological processes following an initial disruption in homeostasis. Given the limited magnitude of the stimulatory response (i.e., usually 30-60% greater than controls at maximum), heightened study design and replication requirements are often necessary to ensure reliable judgments on causality. Even though hormesis is considered an adaptive response, the issue of beneficial/harmful effects should not be part of the definition of hormesis, but reserved to a subsequent evaluation of the biological and ecological context of the response.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Atypon
Loading ...
Support Center