Linear Link Between Chernobyl Radiation Dose, Cancer
Chernobyl accident responsible for three-quarters of thyroid cancers found in study
FRIDAY, July 7 (HealthDay News) -- Exposure to radioactive iodine following the Chernobyl nuclear power plant accident in 1986 increased the risk of thyroid cancer among local adolescents and children in an approximately linear relationship, according to the first cohort study of the exposed population. The excess relative risk of thyroid cancer was 5.25 for each gray of radioactive exposure, the authors report in the July 5 issue of the Journal of the National Cancer Institute.
Researchers led by Geoffrey R. Howe, Ph.D., of Columbia University in New York City, screened 13,127 individuals who were younger than 18 at the time of the accident for thyroid pathology. All patients had exposure estimated from radioactivity measured shortly after the accident and from interview data.
Between 1998 and 2000, the researchers detected 45 cases of thyroid cancer, while 11.2 thyroid cases would have been anticipated in this population without radiation exposure. An approximately linear relationship was seen between radiation dose and thyroid cancer, with an estimated excess relative risk of 5.25 for each gray of exposure. There was a link between greater age at exposure and a lower risk of radiation-related thyroid cancer.
"We estimate that 75 percent of the thyroid cancer cases would have been avoided in the absence of radiation," the authors conclude. "With appropriate adjustment for dose, this estimate demonstrates a substantial contribution of radioactive iodines to the excess of thyroid cancer that followed the Chernobyl accident."