Almost 40 years after the Chernobyl disaster, the areas surrounding the power plant remain dangerous for humans. On April 26, 1986, Reactor 4 of the Vladimir Ilyich Lenin plant exploded, releasing 500 times more radioactive material into Northern Ukraine than was used in the Hiroshima bomb. The site has gradually transformed into a unique environment filled with radioactive animals and plants.
Apart from the small number of humans involved in maintenance, visitors, and those who constructed the New Safe Confinement structure, animals currently roam freely in the area. Among them are dogs–so many that they’ve been affectionately named “the puppies of Chernobyl.” When the accident occurred, these dogs were abandoned. Interestingly, their population has surged in recent years, and it’s estimated that around 1,000 dogs now wander the area.
While these adorable dogs may seem friendly, petting them isn’t advisable due to their radioactive exposure. However, a recent study suggests that the genetic differences observed in these dogs aren’t the result of radiation-induced mutations.
The Radioactive Dogs of Chernobyl
The video above makes the urge to pet the Chernobyl puppies hard to resist, but their fur contains radioactive particles. It seems truly remarkable that these dogs survived so close to the site of the accident.
Ionizing radiation uniquely interacts with living tissues. It breaks chemical bonds and modifies the structure of atomic chains. Due to their specific characteristics, this can lead to the development of tumors in animals, while plants have adapted more effectively to cope with these changes.
The University of South Carolina and the National Human Genome Research Institute recently studied 302 of the 1,000 dogs roaming around Chernobyl. The study aimed to characterize the genetic structure of these dogs. The research team concluded that Chernobyl dogs consist of three distinct populations that have lived within the plant and at distances of 6 to 9 miles from ground zero.
Researchers aimed to address questions about how humans and other species adapt to survive in harsh environments. It seems that these dogs are evolving at a different rate compared to dogs in nearby areas.
Over the years, Chernobyl dogs have developed distinctive genetic traits. A few months ago, a different group of researchers suggested that radiation may not be a contributing factor to these traits. More recently, North Carolina State University and Columbia University shared a study indicating that two populations of dogs, located only about 10 miles apart, have distinct genetic characteristics.
“We are trying to determine if low-level exposure over many years to environmental toxins such as radiation, lead, etcetera, could explain some of those differences,” co-author Matthew Breen says. The team’s approach involved starting with an examination of differences at the chromosomal level. Researchers then investigated small intervals in the genome and finally analyzed nucleotide differences.
Chernobyl’s Reactor 4 in its current sarcophagus.
The goal of the study was to identify anomalies and evidence of DNA mutations in reproductive cells, which can be passed down through generations. “Think of it like using the zoom function on your phone’s camera to get more details–we start with a wide view of a subject and then zoom in,” Breen explains. The findings are intriguing. It seems that radiation doesn’t significantly contribute to the changes observed.
“We know that, for example, exposure to high doses of radiation can introduce instability from the chromosomal level on down. While this dog population is 30 or more generations removed from the one present during the 1986 disaster, mutations would likely still be detectable if they conferred a survival advantage to those original dogs. But we didn’t find any such evidence in these dogs,” Breen adds.
Notably, the findings don’t completely exclude the possibility that selective pressure explains the differences between the two dog populations.
“In human terms, this would be like studying a population that is centuries removed from the one present at the time of the disaster. It’s possible that the dogs that survived long enough to breed already had genetic traits that increased their ability to survive. So perhaps there was extreme selective pressure at the start,” co-author Megan Dillon explains.
Dillon also points out that it’s possible the dogs at the nuclear plant were kept separate from the city’s population after the disaster. “Investigating that question is an important next step that we are now working on,” she says.
Unavoidable Disasters
Co-author Norman Kleiman comments on the broader implications of the nuclear accident. “Most people think of the Chernobyl nuclear accident as a radiological disaster in an abandoned corner of Ukraine, but the potential adverse health implications are much wider,” he says. This is due to the release of several toxins over the years, including heavy metals, lead powder, pesticides, and asbestos.
Interestingly, most of these toxins were discharged into the environment during decades of subsequent cleanup efforts, which may have also affected local living organisms. Kleiman adds, “Studying companion animals like these dogs offers a window into the kinds of adverse health risks that people may face.”
“The importance of continuing to study the environmental health aspects of large-scale disasters like this cannot be overemphasized, as it is certain, given our increasingly technological and industrial societies, there will invariably be other such disasters in the future, and we need to understand the potential health risks and how best to protect people,” Kleiman points out.
As such, understanding the genetic variations in dogs isn’t merely a matter of scientific curiosity. It also serves a practical purpose: understanding the natural risks posed by certain harmful substances. This is crucial in light of the possibility of future disasters of similar magnitude.
Image | Sergey Semin | Tim Porter
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