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gg.docx - The history of radiation carcinogenesis goesback...

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The history of radiation carcinogenesis goesback a long way.The harmful effects of X-rays were observed soon after their discovery in 1895 by W. K. Ro¨ ntgen. The first observed effects were acute, such as reddening and blistering of the skin within hours or days after exposure. By 1902, it became apparent that cancer was one of the possible delayed effects of X-ray exposure. These cancers, which included leukemia, skin cancers, lymphomas, and brain tumors, were usually seen in radiologists only after long-term exposure before adequate safety measures were adopted, thus it was thought that there was a safe threshold for radiation exposure. The hypothesis that small doses of radiation might also cause cancer was not adopted until the 1950s, when data from atomic bomb survivors in Japan and certain groups of patients treated with Xrays for noncancerous conditions, such as enlarged thyroids, were analyzed. These and other data led to the concept that the incidence of radiation- induced cancers might increase as a linear, nonthreshold function of dose. Thus the debate about whether there is a safe threshold pertains to radiation carcinogenesis, just as it does to chemical carcinogenesis. In radiation carcinogenesis, the damage to DNA, and hence its mutagenic and carcinogenic effect, is due to the generation of free radicals as the radiation passes through tissues. The
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  • Fall '19
  • Ionizing radiation, Chernobyl disaster, Radiation poisoning

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