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Future human generations are affected by nuclear radiation

Evidence has been sitting there

Some of the first evidence linking radiation with altered sex ratios among babies emerged after atomic bombs hit Hiroshima and Nagasaki in 1945, though the data was not strong enough to be convincing.

Subsequent bomb tests and animal studies connected radiation exposure and a rise in stillbirths and birth defects. For years, though, detailed records of birth data have been sitting there, just waiting to be analysed.

Using official and publicly available records, Scherb and colleague Kristina Voigt found that the ratio of male-to-female births in eastern and central Europe had been declining slightly for decades leading up to the Chernobyl disaster in 1986.

But in 1987, they reported in Environmental Science and Pollution Research , there was a sudden spike in male births compared to female births in those countries.

The trend continued upward for years, before levelling off around 2000. In the United States and elsewhere, sex ratios have continued downward for a variety of reasons, with no evidence of a spike in the mid-1980s.

440,00 missing girls

Overall, the shift was tiny – on the order of less than half a per cent – with somewhere between 1.045 and 1.06 boys born for every girl, depending on when and where you look.

Spread out over the entire population, though, that adds up to an estimated 440,000 missing girls as a result of the Chernobyl explosion, says Scherb. The researchers suspect that the trends points to a disproportionate loss of female pregnancies as a result of radiation exposure.

In both Europe and the United States, the study also found rises and falls in sex ratios that mirrored the frequency of atomic bomb testing. Those echoes showed a several-year lag that, the researchers proposed, corresponded with the delay in radioactive fallout from the atmosphere.

As a final piece of evidence, the researchers documented an uptick in the relative numbers of male births near nuclear facilities in Germany and Switzerland during periods when those facilities were operating.

Effect occurs early in conception

Ionising radiation – the kind that comes out of bombs and nuclear power plants – has been shown to alter sex ratios in fruit flies and mice, says Karl Sperling, of the Institute for Human Genetics at the University of Berlin. He suspects that radiation exposures might affect DNA in the first few cell divisions around the time of conception, which is known to be a highly vulnerable period.

If radiation can influence sex ratios in this way, he adds, there might be reason to be concerned about other environmental exposures, too.

June 9, 2011 - Posted by Christina Macpherson | 2 WORLD, health