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Estimating Exposure to Iodine - 131

During the 1950s and early 1960s, the U.S. Government conducted about one hundred nuclear weapons tests in the atmosphere at a test site in Nevada. Depending upon their location, people living in the U.S. at that time were exposed to varying levels of radiation, notably from Iodine-131 (I-131). The NCI developed I-131 dose/risk calculator (entitled "Radioactive I-131 from Fallout") is a tool that allows any individual to estimate his or her radiation exposure to I-131 from the Nevada nuclear weapons tests and to estimate fallout-related risks of developing thyroid cancer.

The calculator is offline while researchers update it with additional data. For questions about the calculator, or about your personal risk estimate, please email For more general information, read Get the Facts About Exposure to I-131 Radiation.