The Low-Dose


Hormesis is a dose-response phenomenon characterized by low-dose stimulation and high-dose inhibition. Since dose-responses are often believed to be linear from low-dose to high, the non-linear nature of hormesis and its application in all the scientific fields is of rapidly growing interest among scientists and regulators alike. In turn, the International Dose-Response Society and its quarterly peer-reviewed journal Dose-Response have been created to promote the understanding of the nature, mechanisms, and implications of the dose-response in general and of hormesis in particular.

Oxford English Dictionary Definition of Hormesis

hormesis, noun, Biol
The phenomenon or condition of a substance or other agent having a beneficial physiological effect at low levels of exposure even though toxic or otherwise harmful at higher levels. Used esp. with reference to a known toxin, or to ionizing radiation. 1943 C. M. SOUTHAM & J. EHRLICH in Phytopathology 33 520 An increase in growth rate of many of the fungi in extreme dilutions of the extract is also evident… It is..likely that the phenomenon represents an initial response, followed by progressive desensitization to subinhibitory concentrations of a toxic constituent of the extract. The term hormesis (adj. hormetic) is proposed to designate such a stimulatory effect of subinhibitory concentrations of any toxic substance on any organism. 1963 Lancet 16 Nov. 1041/2 On two occasions Ps. pyocyanea appeared more resistant to streptomycin and showed hormesis with tetracycline. 1972 Science 29 Sept. 1154 Hormesis is a common and widespread phenomenon. Insecticides have been shown to stimulate growth of insects as well as plants, and fungicides can stimulate growth of fungi. 1996 Los Angeles Times (Nexis) 20 May B4 Molecular geneticists have shown that ‘hormesis’, the low-level exposure of an organism to a stress agent that is harmful at higher levels, can actually extend life span in mice and fruit flies.
© Oxford University Press 2007


1943 paper Phytopathology paper by Southam and Ehrlich.

1941 undergraduate thesis of C.M. Southam with the first documented use of “hormesis” [PDF]

Defining Hormesis, Calabrese, EJ and Baldwin, LA [PDF]

Number of Citations for “Hormesis” or “Hormetic: in Web of Science – 1990 through 2008 [PDF]

Radiation Hormesis Conference April 1985 [PDF]