Residents of the area surrounding the damaged Fukushima nuclear power plant in Japan will take no solace from a new health study reported in Science News last week. A long term study of thousands of Ukrainians who were children at the time of the Chernobyl nuclear plant incident experience an elevated risk of thyroid cancer more than 30 years later.
The study, which will be published in full in Environmental Health Perspectives was a project of scientists at the U.S. National Cancer Institute, three U.S. universities and a medical institute in Kyiv, Ukraine. The scientists looked at medical records of Chernobyl survivors for radioactive iodine exposure levels following the 1986 meltdown and monitored them for thyroid cancer decades later. The study confirmed that the people exposed to the largest doses of iodine-131 at the time of the nuclear meltdown were most likely to develop cancer years later.
When asked about the Fukushima situation Kiyo Mabuchi, acting head of the Chernobyl unit at NCI in Bethesda, Md told Science News: “If there is some kind of significant exposure, one should also be concerned with radioactive iodine — especially in children.”
Should the Japanese Government Be Distributing Iodine Tablets to Reduce Cancer Risk?
Because the thyroid uses iodine to generate hormones, the gland readily absorbs the nutrient. Our bodies do not discriminate between benign non-radioactive iodine from food and water or supplements and the radioactive variety when can destroy thyroid tissue and elevate long-term cancer risk.
The results of this study may have been complicated by the emergency response efforts following the Chernobyl meltdown. There was some distribution of potassium iodine tablets intended to inoculate survivors against future cancer by preventing their thyroids from absorbing the radioactive iodine in the environment. Because the study participants were children and records from the disaster response are not clear, it’s not possible to determine exactly who got the tablets. What is clear is that the distribution of those tablets did not eliminate the cancer risk among the survivors.
Unfortunately, the ineffectiveness of prophylactic iodine for these Ukrainians doesn’t translate to a recommendation that Japan forgo such efforts. There was a well documented iodine deficiency among the population in the Chernobyl region, meaning survivors were very likely to absorb both the iodine from potassium iodine from prophylactic tablets and radioactive iodine from the nuclear plant.
The study authors do recommend regular thyroid cancer screenings for Fukushima survivors. Thyroid cancer is very slow to develop and prognosis for survival very good when treatment is started early. Fukushima area residents should be especially vigilant about thyroid health screenings in the coming decades.