Risk of Thyroid Cancer among Chernobyl Liquidators

After the Chernobyl accident in 1986, the “liquidators” or clean-up workers were among those who received the highest radiation doses to the thyroid from external radiation. Some were also exposed to radioiodines through inhalation or ingestion. A collaborative case-control study nested within cohorts of Belarusian, Russian and Baltic liquidators was conducted to evaluate the radiation-induced risk of thyroid cancer. The study included 107 cases and 423 controls. Individual doses to the thyroid from external radiation and from iodine-131 (131I) were estimated for each subject. Most subjects received low doses (median 69 mGy). A statistically significant dose-response relationship was found with total thyroid dose. The Excess Relative Risk (ERR) per 100 mGy was 0.38 [95% confidence interval (CI): 0.10, 1.09]. The risk estimates were similar when doses from 131I and external radiation were considered separately, although for external radiation the ERR was not statistically significantly elevated. The ERR wa...