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Hormesis (from Greek ''hórmēsis'' "rapid motion, eagerness," from ancient Greek ''hormáein'' "to set in motion, impel, urge on") is the term for generally favorable biological responses to low exposures to toxins and other stressors. A pollutant or toxin showing hormesis thus has the opposite effect in small doses as in large doses. A related concept is Mithridatism, which refers to the willful exposure to toxins in an attempt to develop immunity against them. Hormetics is the term proposed for the study and science of hormesis. In toxicology, hormesis is a dose response phenomenon characterized by a low dose stimulation, high dose inhibition, resulting in either a J-shaped or an inverted U-shaped dose response. Such environmental factors that would seem to produce positive responses have also been termed "eustress." The hormesis model of dose response is vigorously debated.〔 The notion that hormesis is important for chemical risks regulations is not widely accepted. The biochemical mechanisms by which hormesis works are not well understood. It is conjectured that low doses of toxins or other stressors might activate the repair mechanisms of the body. The repair process fixes not only the damage caused by the toxin, but also other low-level damage that might have accumulated before without having triggered the repair mechanism. ==History== German pharmacologist Hugo Schulz first described such a phenomenon in 1888 following his own observations that the growth of yeast could be stimulated by small doses of poisons. This was coupled with the work of German physician Rudolph Arndt, who studied animals given low doses of drugs, eventually giving rise to the Arndt-Schulz rule. Arndt's advocacy of homeopathy contributed to the rule's diminished credibility in the 1920s and 1930s.〔 The term "hormesis" was coined and used for the first time in a scientific paper by C.M. Southam and J. Ehrlich in 1943 in the journal: Phytopathology, volume 33, pp. 517–541. Recently, Edward Calabrese has revived the hormesis theory through his research on peppermint plants. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「hormesis」の詳細全文を読む スポンサード リンク
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