Comments
Ionizing radiation, at high doses well above background levels, is the only established environmental cause of brain cancer. Some epidemiological studies have found an increased risk of brain cancer associated with petrochemical workers, rubber and tire workers, electrical workers, health professionals, farmers, and workers with exposures to vinyl chloride and polychlorinated biphenyls. [Adami, p. 494-7] Brain cancer after radiation treatment is "occasionally associated with robust risk estimates." It is seen mainly after high-dose irradiation in childhood, e.g., an estimated dose of 1.5 Gy for treatment of ringworm of the scalp. Brain cancer was not associated with radiation in studies of Japanese A-bomb survivors, radium dial painters, radiologists, underground miners, nuclear workers, and uranium processors. [Boice, p. 260-263] There is suggestive evidence that non-arsenical insecticides and petroleum refining are occupational carcinogens. There is no strong evidence that occupational exposure to ionizing radiation is associated with brain cancer. [Siemiatycki, p. 334]