The Cold War ended more than a decade ago, but scientists continue to assess its effects. From 1949 to 1956, a series of aboveground Soviet atomic tests at the Semipalatinsk nuclear facility in Kazakhstan exposed the local population to varying doses of ionizing radiation. Now, some 40 years later, researchers have discovered a significant increase in the genetic mutation rates of several generations of families that lived nearby. The findings appear in the current issue of the journal Science.

Researchers led by Yuri Dubrova of the University of Leicester analyzed blood samples collected from three generations of some 40 families in Beskaragai, a rural district neighboring the Semipalatinsk site. Specifically, the group looked at so-called minisatellite DNA¿short, repeating sequences sprinkled throughout the genome that are prone to mutation. Comparisons of the heritable mutation rates in these people with those of a nonirradiated, but similar population in Kazakhstan revealed considerable differences. The team found a nearly 80 percent increase in the mutation rate in individuals directly exposed to the radioactive fallout. Even the children of affected individuals showed a 50 percent mutation rate increase over their nonirradiated counterparts. The mutation rates declined steadily after the 1950s, however.

The health consequences of such elevated mutation rates, if any, remain unknown. The study does suggest, though, that the 1963 Moscow treaty banning atmospheric nuclear testing spared a number of people from further genetic mutation.

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