Between 1945 and 1980, the U.S., the U.S.S.R., the U.K., France and China carried out more than 500 atmospheric tests of nuclear weapons totaling the explosive equivalent of 440 megatons of TNT. These tests injected radioactive material into the atmosphere, much of which became widely dispersed before being deposited as fallout. Cancer investigators have been studying the health effects of radiation for decades, including radioactive fallout, making radiation one of the best-understood agents of environmental injury. The legacy of open-air nuclear weapons testing includes a small but significant increase in thyroid cancer, leukemia, and certain solid tumors.
The NCI developed an online calculator to estimate the radiation dose received by the thyroid gland from radionuclides in fallout from nuclear tests. The early version of this tool estimated exposure and risk from fallout from the Nevada Test Site (NTS). In 2017, investigators released a new version of the tool that includes exposures from sites outside of the United States (global fallout). Read more about this and additional enhancements.
The calculator estimates an individual’s risk of developing thyroid cancer from their exposure and provides an estimate of probability of causation, sometimes called assigned share (PC/AS) for individuals who have been diagnosed with thyroid cancer.
For more general information, read Get the Facts About Exposure to I-131 Radiation.