April 1986: an American radio station announces news of what was soon found to be the greatest civil nuclear disaster in history at the Chernobyl nuclear plant in Ukraine: "Radiation monitors in Sweden and Finland this morning are showing unusually high readings, in places three times normal levels. At the moment the source of those emissions is a mystery but speculation has arisen of a nuclear power plant accident inside the Soviet Union..."
Eighteen years later, a team of Czech scientists has come up with a disturbing hypothesis. They think that the Chernobyl disaster of 1986 may have caused a loss of several hundred male babies in Czechoslovakia after their pregnant mothers were exposed to radioactive fallout.
A team, led by Miroslav Peterka from the Institute of Experimental Medicine in Prague unexpectedly revealed an anomaly in the birth pattern in this country.
"Each month in our country, the number of newborn boys is much higher than girls. It means per 100 girls 105 boys are born. We have data from 50 years, it means from 1950 until 2000. And each month, this rule was valid that many more boys were born than girls. Only one exception exists in November 1986 when fewer boys were born than girls."
There should have been some 450 more boys born that month. What could have caused this irregularity in the otherwise stable sex ratio? An explanation suggests itself - the drop in the male birth rate came seven months after the Chernobyl disaster.
No one really knows why, but in general male foetuses are much more vulnerable than female foetuses. Mothers of babies born in November that year would have been in the third month of pregnancy when the cloud of radiation from Chernobyl passed over Czechoslovakia. Doctor Peterka again.
"We think that the most critical period for radiation exposure is the third month of pregnancy. This data about the third month of pregnancy being a critical period correlates with the results of Japanese studies after Nagasaki and Hiroshima."
The Czech Republic lies some 1,100 kilometres west of Chernobyl. As a result of weather conditions, the country was affected by three waves of radiation after the explosion. The strongest one came on April 30th and another two arrived on the 4th and 8th of April, 1986.
Those estimated 450 miscarriages can most likely be blamed on a high concentration of radioactive iodine-131, a radionuclide with a very short half-life, whose readings were much higher in areas with rain, a factor which most likely aggravated the effects of exposure. In parts of Czechoslovakia there was rain on those days.
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