A quick look at “Chernobyl: Relationship between Number of Missing Newborn Boys and the Level of Radiation in the Czech Regions” by Miroslav Peterka, Renata Peterková, and Zbyneˇk Likovsky´ in Environmental Health Perspectives.

As a rule, more boys than girls are born. But in November 1986 in the eastern regions of the Czech Republic, the reverse was true – more girls than boys. It appears that radiation exposure released by the Chernobyl nuclear accident in April 1986, brought to earth by rain over the area, increased radiation exposure. Fetuses that were approximately three months old at the time appear to have been effected, resulting in a reduction of newborn boys six months later.


According to the authors, “A greater vulnerability is known of male fetuses to prenatal damage by environmental stress. That is why the long-standing higher male birth fraction is considered as a sensitive indicator of stability and health in human reproduction. In this case, the authors hypothesize that “a large release of iodine-131 and other shorter-lived isotopes of iodine resulted in damage of the thyroid gland in fetuses and/or their mothers. A serious damage of the thyroid gland in three months old fetuses in end of April – beginning of May by radioiodine might be one of the main reasons for their loss detected as a decrease in male birth fraction in November 1986.”

It is widely recognized that taking potassium iodine blocks uptake of radioactive iodine, thereby reducing radiation exposure and preventing thyroid cancer. Authorities in Poland distributed potassium iodine tablets shortly after the Chernobyl accident, but it appears from the paper that Czech authorities failed to do so.

This new study suggests that in utero exposure to radioactive iodine during the third month of pregnancy may increase risk of fetal loss, and that strong measures should be taken to avoid exposure during this period.

Citation: Peterka M, Peterková R, Likovsk Z. 2007. Chernobyl: Relationship between Number of Missing Newborn Boys and the Level of Radiation in the Czech Regions. Environ Health Perspect 2007;115:1801–1806.

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