net/) (Table 2), four out of six women (66.7%) tested in March exhibited a much higher 131I radioactivity than women tested by our group in April. The amount of 131I radioactivity decreased over time in two women (cases 26 and 28), as was seen in seven women in our study (Table 1, cases 1 and 6–11). Thus, the contamination
of breast milk with 131I may have reflected the degree of environmental pollution with 131I. However, if the citizens group had used an assay system similar to the one used by our group, which is able to detect 131I at a level of around 2.0 Bq/kg, the detection ratio of 131I among the 28 women may have been higher than the reported rate of 14.3% (4/28). The most reliable data to date on the relationship between the thyroid selleck radiation dose and
BAY 73-4506 cost the risk for thyroid cancer following the environmental release of 131I was obtained after the Chernobyl reactor accident in April 1986.6 Thyroid exposure to radiation after the Chernobyl reactor accident was virtually all internal, from radioiodines.6 The inhalation of airborne 131I may occur after its release and prior to the deposition of 131I on the ground; however, in seven Ukraine cities following the release of radioiodine from the Chernobyl nuclear power plant, the inhalation of 131I was estimated to contribute to between 2 and 13% of the total absorbed radiation dose, whereas the ingestion pathway contributed between 87 and 98%.8 Therefore, human breast milk was speculated to Galeterone contribute to the dose of 131I received by nursing infants in the vicinity of the Chernobyl reactor accident. Iodine is an essential nutrient required for the production of thyroid hormone, and the diet is the major source of iodine intake. Cows and goats absorb iodine from ingested vegetables and water. The absorbed iodine is then excreted into their milk.9 In addition, 131I administered orally or intravenously for medical purposes also accumulates in the thyroid and breast tissues and is excreted in breast milk.3–5 These findings have supported
the speculation that human breast milk contributed to the development of thyroid cancer in infants after the Chernobyl accident. In some regions, for the first four years after the accident, the incidence of thyroid cancer among children aged 0 to 4 years old at the time of the accident exceeded the expected number of cases by 30- to 60-fold.6 Before the end of the first decade, the annual incidence of thyroid cancer increased in children under the age of 15 years at the time of accident from a baseline incidence of <1.0 per 100 000 individuals to >100 per 100 000 individuals in the region with the highest contamination levels.10–13 A significant correlation is seen between the level of iodine intake and the iodine content of human milk, with a correlation coefficient (r) of 0.41 or 0.82.