Now the study is undergoing review by independent scientists. Jim Ruttenber, who helped start the thyroid disease study and is now at the University of Colorado School of Medicine, said he questioned the statistical power of the study. The study estimated the radiation to 3,441 downwinders who were young children during the heaviest airborne releases and grouped them into categories. In comparison, other speakers pointed out that 400,000 children were exposed to much greater amounts of radiation from the Chernobyl nuclear accident in 1986 in Ukraine. Increased incident of thyroid cancer was found in those children.
Radioactive iodine is known to concentrate in the thyroid gland.
Those children were exposed in a single incident and four years later thyroid disease was evident to researchers. But much smaller Hanford releases were spread from 1944 through the early 1950s. There must have been exposures and there will be cancers, but it's much more difficult to pick them out from background diseases. About five of every 1,000 people worldwide develop thyroid cancer. Using the data from Chernobyl that calculated the risk of children developing thyroid cancer there from different exposure levels, the risk of the average Hanford downwinder of developing the cancer is still less than six in 1,000, calculated Darrell Fisher, a medical physicist at Pacific Northwest National Laboratory.