Chernobyl nuclear disaster: Worms at affected site 'exceptionally resilient' to radiation

The 1986 Chernobyl disaster is among the worst nuclear energy accidents of all time. A total of 50 people died of acute radiation syndrome and thousands of others might die in future due to radiation-related causes. Humans were evacuated from the Chernobyl Nuclear Power Plant but many plants and animals continue to live in the region, despite the high levels of radiation that persist nearly four decades later.

Now, a study by New York University has found that exposure to chronic radiation from Chernobyl has not damaged the genomes of microscopic worms living there today.

The study, published in PNAS (Proceedings of the National Academy of Sciences) on March 5, said the non-damage did not mean that the region was safe but suggested that these worms were "exceptionally resilient."

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"The 1986 disaster at the Chornobyl Nuclear Power Plant transformed the surrounding region into the most radioactive landscape known on the planet. Whether or not this sudden environmental shift selected for species, or even individuals within a species, that are naturally more resistant to mutagen exposure remains an open question," the study said.

Sophia Tintori, the author of the study said that Chernobyl was a tragedy of incomprehensible scale, but researchers still did not have a great grasp on the effects of the disaster on local populations.

“Did the sudden environmental shift select for species, or even individuals within a species, that are naturally more resistant to ionizing radiation?” Tintori said.

To dig into this, Tintori and her colleagues turned to nematodes, tiny worms with simple genomes and rapid reproduction, which makes them particularly useful for understanding basic biological phenomena.

The study's senior author Matthew Rockman said, these worms live everywhere, and they live quickly, so they go through dozens of generations of evolution while a typical vertebrate is still putting on its shoes.

In 2019, Tintori and Rockman visited the Chernobyl Exclusion Zone to see if chronic radiation had had a detectable impact on the region’s worms. The researchers gathered worms from samples of soil, rotting fruit, and other organic material.

Worms were collected from locations throughout the zone with different amounts of radiation, ranging from low levels on par with New York City (negligibly radioactive) to high-radiation sites on par with outer space (dangerous for humans, but unclear if it would be dangerous to worms).

After the samples were collected, the team brought them to biologist Timothy Mousseau's (a member of the 2019 visit) field lab in a former residential home in Chornobyl, where they separated hundreds of nematodes from the soil or fruit.

The researchers were surprised to find out that using several different analyses, they could not detect a signature of radiation damage on the genomes of the worms from Chernobyl. But this did not mean that Chernobyl is safe, "it more likely means that nematodes are really resilient animals and can withstand extreme conditions,” noted Tintori.

“We also don’t know how long each of the worms we collected was in the Zone, so we can't be sure exactly what level of exposure each worm and its ancestors received over the past four decades,” she added.