Valentina Drozd, M.D. Ph.D.
Belarusian Medical Academy for Postgraduate Education, Minsk, Belarus
About twenty six years passed after the Chernobyl accident and as post-Chernobyl period showed, there was a sharp increase in thyroid cancer in children aftermath the accident that suggested radiation etiology.
Unfortunately, reliable information about the accident and the resulting dispersion of radioactive material was initially unavailable to the affected people in what was then the Soviet Union and remained inadequate for years following the accident. This failure and delay led to widespread distrust of official information and the mistaken attribution of many ill health conditions to radiation exposure. Anyway, no once prognosis just after Chernobyl accident suspected such an early a sharp increase of pediatric thyroid cancer in Belarus.
Previous studies of radioactive fallout from Marshall Islanders and the Nevada test site indicated a lower contribution of the shorter-lived radioactive iodine and the risk of thyroid cancer was not statistically significantly increased. Exposure of 3440 young children in the 1940s1950s to fallout from essentially pure Iodine-131 from the Hanford nuclear site did not lead an increased risk of thyroid cancer at doses on the order of 0,17 Gy (maximum dose 1 Gy) that was based on 19 observed cancers. Among more than 6000 children administered known amounts of 1 Iodine-131 for diagnostic purposes (mean dose = 1 Gy) also were not revealed an increased risk of thyroid cancer, but the numbers of children exposed under the age of 10 are small.
In the early nineteen I and my colleagues screened the condition of thyroid among exposed children in polluted areas and we first reported about abnormal increasing of number of thyroid cancer cases in children in Belarus. This information was greeted skeptically in the West and US as it was not thought plausible that exposure to radio-isotopes of iodine in fallout could lead to such an increase in thyroid cancer with such a short latency. Special epidemiological investigations and large-scale screening studies were organized to precise the true rise in thyroid pathology and its radio induced character. Comparison of data obtained by different investigators in 1990-2010 shows that the prevalence of thyroid carcinoma varied within 0.2%-0.62%. All studies have concordantly demonstrated the frequency of thyroid carcinoma and thyroid nodules exceeding the official statistics in 10 and more times. In retrospect, it can be seen that the skepticism was unjustified. Nowadays it has been proofed that the dramatic increase in the incidence of radiation induced thyroid cancer in subjects exposed to ionizing radiation in childhood is the most significant health consequence of the Chernobyl accident in Belarus, Ukraine and the Russian Federation.
The increasing incidence of thyroid cancer observed during the last 15 years not only in Belarus but also in the United States, Europe and other developed countries is considered to be a real medical problem. While the incidence of many head and neck cancers in the United States is decreasing, a number of registries have reported the increasing incidence of thyroid cancer. Papillary thyroid cancer in the United States more than doubled over the past 30 years from 2.7 to 11.9 per 100,000 (2011), the incidence of thyroid cancer is increasing faster than any other cancer. The reasons of this situation were not completely clear. One of them is the high level of prevalence of thyroid cancer among people emigrated from the former Soviet Union (Screening data of “Project Chernobyl” New-York).
However, the situation in Fukushima is not the same as the situation after Chernobyl accident: the doses of exposure are significantly lower, there is no iodine deficiency in Japan, iodine prophylaxis was done at the time and according the high standard. All possibilities of International cooperation and an exchange of experience were used for mitigation of consequences of the techno-genic accidents.
In that manner, we can predict that the effects of exposure in the Fukushima will ¬be significantly smaller than the once for the Chernobyl area residence.
Our visit to the FUKUSHIMA INSTITUTE let us believe that a major work in screening and identification of thyroid disorders is taking place. Also, a great deal of attention is being paid to explaining to the population ways of correct behavior and acting in such situation. But the actions that are taken in ultrasound screening show how important are early identification and the prophylactics of thyroid disorders.
Visiting the regions that were affected by the tsunami showed how tragic the accident is, but also convinced that the powerful spirit of Japanese people can deal with this problem and become even stronger.