What Chornobyl dogs' Survival Tells Us

Science News :  March 11, 2023: Researchers from North Carolina State, Columbia University
Mailman School of Public Health,

University of South Carolina, and the National Institutes of Health discovered that two groups of dogs living in the
Chornobyl Exclusion Zone, one at the site of the former Chornobyl reactors and another at a different location, had
different coping mechanisms for extreme environmental pressures like exposure to radiation, heavy metals, or toxic chemicals. The findings show that these are two separate groups that infrequently interbreed.
This is the first examination into the genetic makeup of stray dogs living close to the Chornobyl nuclear power station, whereas other studies concentrated on the effects of the tragedy on various wildlife species.

More than 300,000 locals were forced to relocate after the 1986 Chornobyl nuclear power plant disaster,
and a 30-kilometer-radius "no man's land" was created around the damaged reactor complex. While the crisis was directly caused by a major steam explosion that sent enormous amounts of ionizing radiation into the air, water, and land, radiation exposure is not the only environmental concern that resulted from the calamity. An ecological and environmental catastrophe as a result of the chemicals, toxic metals, pesticides, and organic compounds that have been left behind by years of cleanup work as well as from decaying and abandoned buildings, such as the neighboring Pripyat military post and the abandoned city.

A larger number of dogs were employed in earlier study by the co-authors, led by collaborators at the NIH, to demonstrate the separation of the two populations and the complexity of their respective family structures.

Somehow, two small populations of dogs managed to survive in that highly toxic environment," noted Norman J. Kleiman, PhD, assistant professor of Environmental Health Sciences at Columbia Mailman School of Public Health, and a co-author. "In addition to classifying the population dynamics within these dogs at both locations, we took the first steps towards understanding how chronic exposure to multiple environmental hazards may have impacted these populations."

"The overarching question here is: does an environmental disaster of this magnitude have a genetic impact on life in the region?" says Matthew Breen, Oscar J. Fletcher Distinguished Professor of Comparative Oncology Genetics at NC State, and a corresponding author. "And we have two populations of dogs living at and near the site of a major environmental disaster that may provide key information to help us answer that question."

In a separate study, the scientists examined dog DNA samples that included four times as many genetic mutations, giving them a better view of the genomes. The research was also able to locate 391 outlier areas in the canine genomes that were different between dogs living at the two locations, proving that the two populations are truly genetically diverse.

"The question we must answer now are why are there striking genetic differences between the two dog populations?" says Megan Dillion, PhD candidate at NC State and a lead author of the published study. "Are the differences just due to genetic drift, or are they due to the unique environmental stressors at each location?"

"The dog is a sentinel species," Breen says. "By and teasing out whether or not the genetic changes we detected in these dogs are the canine genome's response to the exposures the populations have faced, we may be able to understand how the dogs survived in such a hostile environment and what that might mean for any population -- animal or human -- that experiences similar exposures."

"Though 37 years have passed since the accident, the ~30-year-long half-lives of lingering radioisotopes means the danger posed by radiation exposure is still very much real," notes Kleiman, who is also director of the Columbia University Radiation Safety Officer Training course. "When radiation exposure is combined with a complex toxic chemical mixture of uncertain composition, there are very real human health concerns raised for the thousands of people who continue to work within the Exclusion Zone on continuing cleanup efforts as well as at two newly constructed nuclear fuel reprocessing plants."

"Understanding the genetic and health impacts of these chronic exposures in the dogs will strengthen our broader understanding of how these types of environmental hazards can impact humans and how best to mitigate health risks."

WNCtimes by Marjorie Farrington