The Chernobyl nuclear power plant accident happened on April 26, 1986. We investigated the cause of the striking increase in frequency of thyroid cancer in children who lived within a 150 km radius of Chernobyl and who were born before and after the accident. No thyroid cancer was seen in 9472 children born in 1987-89, whereas one and 31 thyroid cancers were recorded in 2409 children born April 27, 1986, to Dec 31, 1986, and 9720 born Jan 1, 1983, to April 26, 1986, respectively. Short-lived radioactive fallout caused by the Chernobyl accident probably induced thyroid cancer in children living near Chernobyl.
The level of radiation exposure in children in Belarus caused by the Chernobyl accident was investigated on the basis of whole body 137Cs count. The subjects were 10,062 children (4,762 boys and 5,300 girls) in Mogilev and Gomel, Belarus, who received Chernobyl Sasakawa Health and Medical Cooperation Project health examinations from May 1991 to December 1992 and who were 5-16 y old at the time of examination. The median whole body 137Cs count per body weight varied from 21-48 Bq kg-1 and from 28-126 Bq kg-1 in Mogilev oblast and Gomel oblast, respectively. (The "oblast" is the largest administrative district constituting the country. Belarus consists of 6 oblasts). Corresponding annual effective dose equivalents were all less than the public dose limit of 1 mSv y-1, but the observed levels in the children were considerably higher than the average level of 2.3 Bq kg-1 reported in the past for the former Soviet Union.
Comment In: Health Phys. 1995 May;68(5):733-57730075
The paper considers the radiation doses of the thyroid gland in the inhabitants from the Ukrainian SSR areas (Kiev, Zhitomir, Chernigov, and Vinnitsa Regions), which have been obtained by instrumental studies of thyroidal radioactivity in May-June, 1986, and calculated by the most conservative single-dose administration model. A hygienic evaluation has been made of the findings, taking into account the age and residence. The cumulative irradiation doses of the thyroid have been estimated for children and adults. Possible late sequelae for the areas in question may account for 1060 and 300 thyroid carcinoma cases during the whole life for children and adults, respectively.
We reviewed histopathologically 19 cases of childhood thyroid cancer occurring between 1991 and 1994 among 14,396 screening subjects in Gomel, Republic of Belarus, the region most severely radio-contaminated by the Chernobyl nuclear power plant accident in 1986. The patients were 13 girls and 6 boys with a mean age of 10.6 years. The mean age at the time of the accident was 3.2 years. Mean tumor diameter was 16 mm, and all cases were papillary carcinoma with various amounts of solid component. Psammoma bodies and stromal fibrosis were encountered to some extent in almost all cases. The tumors were highly prone to local invasion and regional lymph-node metastasis. No morphological evidence for radiation-induced cancer was obtained in these cases. 137Cs levels were relatively high in the patients' bodies and in the soil at the places of domicile. However, there was no dose-response relationship between cancer prevalence and radioactivity. These facts suggest that the incidence of aggressive pediatric thyroid cancer is extremely high in Gomel, where most of the children were exposed to a low level of radioactivity over a long time after the accident. At present, however, no definite conclusion can be drawn on the relationship between cancer occurrence and radioactive contamination.
The data on the assessment of the radiobiological situation and the results of clinical and epidemiological studies into the population health status, exposed to radiation because of the Chernobyl NPP accident are summarized. Appropriate regularities in soil contamination with 137Cs are ascertained. It has been shown that the disease incidence among the children's and adult population of the controlled areas is associated not only with improvement of the disease revealing but with the influence of the accident consequences.
Radioactive iodine is released at every atomic-bomb testings and nuclear plants accidents and radioactive iodine is taken up by thyroid glands (internal radiation). In addition to the internal radiation, radioactive fallout causes the external radiation and thyroid glands are known to be sensitive to the external radiation. Furthermore, patients with radiation-induced thyroid disease can survive for a long time regardless of the treatment. The survey of thyroid diseases, therefore, is very sensitive and reliable ways to investigate the effects of radiation caused by atomic bomb explosion, testing and various types of nuclear plants' accidents. Our group from Nagasaki University was asked investigate the thyroid diseases and joined to the Sasakawa Project. In order to investigate the effects of radiation on thyroid disease, it is essential 1) to make a correct diagnosis in each subject, 2) to calculate a correct radiation dose in each subject and finally, 3) to find out the correlation between the radiation dose and thyroid diseases including age-, sex- and area-matched controls. We have established 5 centers (1 in Russia, 2 in Belarus, 2 in Ukraine) and supplied the most valuable ultrasonography instruments, commercial kits for the determination of serum free T4 and TSH level and for the autoantibodies, instrument for urinary iodine measurements, syringes, tubes, refrigerators, etc. We visit each center often and asked peoples at centers to come to Japan for training. Protocol of investigation is essentially the same as that in Nagasaki, and we are planning to investigate more than 50,000 children within 5 years. We are hoping to show a definite conclusion in the near future.(ABSTRACT TRUNCATED AT 250 WORDS)