Radiation hormesis in relation to radiation protection.
A radiation-induced adaptive response has been convincingly demonstrated in a variety of cultured cells. It is associated with the activation of genes and the up-regulation of protein enzymes, resulting in a delay in cell-cycling and the opportunity to repair radiation-damaged DNA as a transient phenomenon. Just how the adaptive response operates in a multi-cellular organism is still obscure, but there is little or no evidence in rodents and the beagle dog of a shortening of lifespan after exposure to acute doses up to a few hundreds of mGy or after chronic daily exposure resulting in accumulated doses of up to a few Gy. Nevertheless there is an increase in both non-neoplastic and neoplastic diseases which need not be life-threatening. A prudent approach has been used by the ICRP in deriving a value for radiation-induced detriment at low doses from which to recommend individual dose and risk limits in their system of radiological protection. This is not to deny the possible existence of an adaptive response. However, in the opinion of the author, there is no overwhelming evidence to date which justifies the belief that exposure to low doses in the range of natural background up to a few tens of mSv reduces the incidence of radiation-induced cancer in a population composed of persons of all ages with a wide spectrum of diseases and with widely different sensitivities to radiation.
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D000222:Adaptation, Physiological; D000818:Animals; D006801:Humans; D008214:Lymphocytes / Q000528:radiation effects; D009381:Neoplasms, Radiation-Induced; D011829:Radiation Dosage; D011832:Radiation Injuries; D011835:Radiation Protection