Transgenerational Effects of Ionizing Radiation from Chernobyl Found in Offspring
A study has revealed that DNA damage resulting from ionizing radiation (IR) due to the 1986 Chernobyl nuclear disaster is detectable in the children of those initially exposed. This marks the first time such a hereditary link has been clearly identified.
Past research has struggled to conclusively determine if this type of genetic damage can indeed be inherited from parent to child. However, the team from the University of Bonn in Germany took a slightly different approach in their investigation.
Instead of focusing solely on new DNA mutations in the next generation, they looked for clustered de novo mutations (cDNMs)—which involve two or more mutations occurring close together, found in the children but absent in their parents. These mutations are thought to arise from DNA breaks in the parental genes as a result of radiation exposure.
“We observed a notable increase in the cDNM count among the offspring of irradiated parents, along with a potential correlation between estimated radiation doses and the number of cDNMs found in those children,” the researchers noted in their published findings.
“While there is some uncertainty regarding the exact nature and amount of ionizing radiation involved, this study is the first to provide evidence supporting a transgenerational effect of prolonged low-dose paternal exposure on the human genome.”
The research involved whole genome sequencing of 130 children of Chernobyl cleanup workers, 110 children of German military radar operators likely exposed to stray radiation, and 1,275 children of unexposed parents who served as control subjects.
The findings revealed an average of 2.65 cDNMs per child in the Chernobyl group, 1.48 in the German radar group, and 0.88 in the control group. While the researchers caution that these figures might be overestimates due to data noise, the differences remained significant after statistical adjustments were made.
Moreover, higher radiation doses in parents generally corresponded to greater numbers of clusters in their children. This aligns with the understanding that radiation can generate reactive oxygen species, which can cause DNA strand breaks that lead to the clusters observed in this investigation when repaired imperfectly.
On a more reassuring note, the research indicated that the health risks for these children appear to be relatively low. Children of exposed parents did not show an increased risk of disease, partly because many of the cDNMs likely occur in non-coding DNA rather than in genes that encode proteins.
“Considering the minimal overall increase in cDNMs from paternal exposure to ionizing radiation and the small proportion of the genome that is protein-coding, the chance of a disease in the offspring being triggered by a cDNM is unlikely,” the researchers explained.
In comparison, it’s known that older fathers tend to pass on more DNA mutations to their children, and the associated disease risk from parental age at conception is higher than the risks posed by the radiation exposure examined here.
However, there are some caveats to this study. Since the initial exposure occurred decades ago, researchers relied on historical records and older devices to estimate exposure levels.
Additionally, the voluntary nature of participation may have created some bias, as those who believed they were exposed to radiation might have been more inclined to take part in the study.
Even with these limitations, the findings underscore that prolonged exposure to ionizing radiation can leave lasting, subtle changes in the DNA of future generations—highlighting the importance of safety measures and monitoring for those at risk.
“The potential for the transmission of radiation-induced genetic changes to future generations is particularly concerning for parents who may have experienced higher doses of IR, possibly for extended periods deemed unsafe,” the researchers wrote.
The study has been published in Scientific Reports.
