Thyroid cancer in children in Belarus after Chernobyl.

The accident to the nuclear reactor at Chernobyl in the Ukraine in April 1986 led to the exposure of substantial populations in northern Ukraine and southern Belarus to radioactive fallout. Recently increases in the incidence of childhood thyroid cancer have been reported from these areas. The possible causal association between exposure to the isotopes of iodine in the fallout and the increased thyroid cancer is examined, with a view to predicting the public health consequences of this aspect of the accident. The reported increases are shown to be consistent with a causal association and, if this is established, then a substantial increase in thyroid cancer can be expected over the next 50 years in the exposed populations. This conclusion underlines the urgent need for research to establish beyond doubt the origin of the reported increases and to formulate an appropriate public health response, including exploration of possible mitigating measures for the future.