Four decades after the Chernobyl nuclear power plant disaster, the children of the workers are still living with the fallout.
Until now, scientists haven’t been sure whether the children of people exposed to radiation would inherit their parents’ genetic damage.
But researchers from the University of Bonn have now shown that children of cleanup workers at the power plant have an increased number of mutations in their DNA.
Instead of looking for all new DNA mutations, the researchers looked for something called ‘clustered de novo mutations’ (cDNMs).
These are where two or more mutations not found in the parent’s DNA are clumped together, which shows that the DNA strand has been broken and badly repaired.
The researchers sequenced the genomes of 130 children of Chernobyl workers, 110 children of German military radar operators exposed to stray radiation, and 1,275 regular people.
On average, children whose parents helped clean up Chernobyl had 2.65 cDNMs, while children of radar operators had 1.48.
For comparison, children whose parents had not been exposed had only 0.88 cDNMs per person.
Researchers have shown that children of Chernobyl cleanup workers (orange) and German radar operators exposed to stray radiation (red) have a higher number of mutations in their genes than the average person (blue)
The parents had either been inhabitants of the town of Pripyat (pictured) at the time of the accident or had been employed as liquidators charged with guarding or cleaning the accident site.
Importantly, the study also revealed that there was a direct association between the intensity of the parents’ radiation exposure and the number of mutations in the children.
The researchers caution that these figures may be slightly inflated due to statistical noise and a relatively small sample size, but the difference was still significant even after accounting for these factors.
In their paper, published in the journal Scientific Reports, the researchers write: ‘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 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 parents had either been inhabitants of the town of Pripyat at the time of the accident or had been employed as liquidators charged with guarding or cleaning the accident site.
When their bodies were hit with ionising radiation from the nuclear reactor, the scientists believe that particles called reactive oxygen species were created.
These are highly reactive, unstable oxygen–containing molecules that have the ability to smash through DNA chains.
These reactive oxygen species damaged the DNA inside developing sperm cells, leaving behind clusters of mutations.
The researchers found an association between individual radiation doses in the parents and the number of clustered mutations in the DNA. The more radiation someone was exposed to, the more mutations their children had
Even though their parents were exposed to the fallout from Chernobyl (pictured), the children’s risk of disease was no higher than that of an average person
When these people eventually had children, those mutations were passed down and became part of their offspring’s genetic code.
Luckily, the researchers found that the risk of disease caused by these mutations was extremely low.
The cDNMs found in the children were located in ‘non–coding’ parts of their DNA, as opposed to the ‘coding’ parts that are responsible for producing certain proteins.
This means that they don’t cause any harmful effects, and the children of Chernobyl workers weren’t at any greater risk of disease than the general population.
For reference, studies have also shown that older fathers pass on a greater number of mutations to their children.
The researchers found that the father’s age at conception created a bigger risk of disease in the children than radiation exposure.
This may be partly because the parents of children in this study were only exposed to relatively low levels of ionising radiation.
For comparison, their estimated ionising radiation exposure was around 365 miligrays, while NASA limits the total career–long exposure of astronauts to 600 miligrays.
WHAT HAPPENED DURING THE 1986 CHERNOBYL NUCLEAR DISASTER?
On April 26, 1986 a power station on the outskirts of Pripyat suffered a massive accident in which one of the reactors caught fire and exploded, spreading radioactive material into the surroundings.
More than 160,000 residents of the town and surrounding areas had to be evacuated and have been unable to return, leaving the former Soviet site as a radioactive ghost town.
A map of the Chernobyl exclusion zone is pictured above. The ‘ghost town’ of Pripyat sits nearby the site of the disaster
The exclusion zone, which covers a substantial area in Ukraine and some of bordering Belarus, will remain in effect for generations to come, until radiation levels fall to safe enough levels.
The region is called a ‘dead zone’ due to the extensive radiation which persists.
However, the proliferation of wildlife in the area contradicts this and many argue that the region should be given over to the animals which have become established in the area – creating a radioactive protected wildlife reserve.
