Tiny worms tolerate Chornobyl radiation, new research shows

The 1986 disaster at the Chornobyl nuclear power plant transformed the surrounding area into the most radioactive landscape on Earth. Humans were evacuated, but many plants and animals continue to live in the region, despite the high levels of radiation that persist nearly four decades later.

A new study appearing in Proceedings of the National Academy of Sciences and led by researchers at New York University finds that exposure to chronic radiation from Chornobyl has not damaged the genomes of microscopic worms living there today—which doesn't mean that the region is safe, the scientists caution, but suggests that these worms are exceptionally resilient.

In recent years, researchers have found that some animals living in the Chornobyl Exclusion Zone—the region in northern Ukraine within an 18.6-mile radius of the power plant—are physically and genetically different from their counterparts elsewhere, raising questions about the impact of chronic radiation on DNA.

"Chornobyl was a tragedy of incomprehensible scale, but we still don't have a great grasp on the effects of the disaster on local populations," said Sophia Tintori, a postdoctoral associate in the Department of Biology at NYU and the first author of the study. "Did the sudden environmental shift select for species, or even individuals within a species, that are naturally more resistant to ionizing radiation?"

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.

"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," said Matthew Rockman, a professor of biology at NYU and the study's senior author.

"I had seen footage of the exclusion zone and was surprised by how lush and overgrown it looked—I'd never thought of it as teeming with life," added Tintori. "If I want to find worms that are particularly tolerant to radiation exposure, this is a landscape that might have already selected for that."

The worms of Chornobyl

In collaboration with scientists in Ukraine and U.S. colleagues—including biologist Timothy Mousseau of the University of South Carolina, who studies the effects of radiation from the Chornobyl and Fukushima disasters—Tintori and Rockman visited the Chornobyl Exclusion Zone in 2019 to see if chronic radiation has had a detectable impact on the region's worms.

With Geiger counters in hand to measure local levels of radiation and personal protective gear to guard against radioactive dust, they 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 of unclear if it would be dangerous to worms).

After collecting samples in the field, the team brought them to Mousseau's field lab in a former residential home in Chornobyl, where they separated hundreds of nematodes from the soil or fruit. From there, they headed to a Kyiv hotel, where—using travel microscopes—they isolated and established cultures from each worm.