The 1986 Chernobyl nuclear disaster in Ukraine stands as history's most devastating nuclear accident, leading to estimated thousands of deaths both immediately and in the decades following the explosion.
Nearly four decades later and the 20-mile 'dead zone' around Chernobyl remains uninhabitable.
For years, scientists haven't been sure whether the children of people exposed to radiation would inherit their parents' genetic damage.
But new groundbreaking research shows that children of cleanup workers at the power plant carry more mutations in their DNA.
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Rather than searching for all possible new DNA mutations, researchers at the University of Bonn focused on something specific called 'clustered de novo mutations' (cDNMs). These occur when two or more mutations - not present in the parents' DNA - are grouped. This indicates that a DNA strand had been broken and poorly repaired during the healing process.
In the study, the researchers analysed the genomes of 130 children whose parents worked at Chernobyl, 110 children of German military radar operators exposed to stray radiation, and 1,275 from the general population as a control group.
The findings, published in Scientific Reports, found that the children whose parents helped clean up Chernobyl averaged 2.65 cDNMs, while children of radar operators had 1.48.
The affected parents had either been residents of the town of Pripyat at the time of the accident or had been assigned as liquidators to guard or clean the accident site.
Meanwhile, children whose parents had not been exposed to radiation had only 0.88 cDNMs per person.
According to the study, the team found a direct association between the intensity of parental radiation exposure and the number of mutations present in their children.
"We found a significant increase in the cDNM count in offspring of irradiated parents, and a potential association between the dose estimations and the number of cDNMs in the respective offspring," the researchers wrote in their paper. "The present study is the first to provide evidence for the existence of a transgenerational effect of prolonged paternal exposure to low–dose [ionising radiation] IR on the human genome."
The researchers noted that the figures may be slightly inflated due to a relatively small sample size, but the difference in mutation number is still noteworthy.
When their bodies were exposed to radiation, the scientists believe it triggered the formation of reactive oxygen species, highly reactive, unstable oxygen–containing molecules that can tear apart DNA strands.
As the DNA in sperm cells becomes damaged, it leaves behind clusters of mutations that are passed down and become part of their offspring's genetic code.
Despite the findings, the researchers discovered that the disease risk associated with these mutations is extremely minimal.
As the cDNMs found in the children were in 'non–coding' parts of their DNA, they don't cause any harmful effects, and the children of Chernobyl workers face no greater disease risk than the general population.