Radiation hormesis.

"Radiation hormesis" is the name given to the putative stimulatory effects of low level ionizing radiation (generally in the range of 1-50 cGy of low-LET radiation). Based on historical and pharmacologic principles reminiscent of some of the major tenets of homeopathy, most of these effects are now generally ascribed to protective feedback systems that, upon exposure to low concentrations of toxins, proceed to stimulate metabolic detoxification and repair networks. The activation of these networks may then result in net beneficial effects on the cell, organism or species. Discussions of possible stimulatory effects of low levels of ionizing radiation have recently become entangled with the separate but related question of whether a threshold dose level exists on the radiotoxicologic dose-response curve. This review summarizes some of the relevant historical and scientific data bearing on the question of radiation hormesis. We find the data in support of most of the hormesis postulates intriguing but inconclusive.