The catastrophe began shortly after midnight on April 26, 1986. A test in reactor block 4 of the Chernobyl nuclear power plant went wrong, a meltdown occurred, explosions tore off the cover plate over the reactor core and released large amounts of radioactive material. Iodine and cesium released for ten days enter the atmosphere and spread over large areas. It is the worst accident at a nuclear power plant to date and, until Fukushima in 2011, the only accident to reach the highest level on the INES nuclear incident scale.
An area of approximately 150,000 km²2 There is radioactive contamination in Ukraine, Belarus and Russia. The area in the immediate vicinity of the reactor, including the entire city of Pripyat, is so polluted that people there have had to flee their homes. They are not allowed to return; a restricted zone is established. Only a few residents return to the zone illegally. And so-called stalkers lead curious people through the restricted area without permission, and later legal tourism arises. Only less heavily polluted areas may be visited for short periods.
In the irradiated zone, which is almost completely abandoned by people, strange things happen – similar to the film “Stalker” (1979) by Andrei Tarkovsky. It’s as if a huge involuntary experiment is taking place here. The high radiation doses lead to increased mutations in animals and plants, sometimes with surprising results. The latest example of this is the discovery by a team of researchers from Princeton University that wolves in the exclusion zone have gene mutations that increase the chance of surviving cancer.
What is a disaster for humans can be a boon for the flora and fauna of the zone. The deadly radiation hit animals particularly hard: only a few percent of worms, insects and spiders still lived within a radius of seven kilometers around the reactor in the summer. Most rodents did not survive until the fall. Miscarriages, deformities and tumors increased sharply. But the radiation soon decreased significantly, as some of the released radioactive elements decayed after a short time. Now the rodent populations have recovered and radiation-resistant birches have replaced the dead coniferous forest in the flora area.
Nevertheless, radiation remains high almost 38 years after the catastrophe, because long-lived radioactive substances such as caesium-137 or strontium-90 (both have a half-life of about 30 years) are far from decaying. Despite these constant pressures, wildlife populations have largely recovered, in part because human influence has disappeared. The population of elk, deer, foxes, wild boars and eagles has remained stable or even increased.
The animals have apparently developed a kind of radiation resistance, as studies in birds show: the radiation exposes their bodies to oxidative stress caused by free radicals, which can damage the genetic material. However, many species were able to adapt to it physiologically – even better, it seems, the higher the radiation exposure.
This also seems to apply to the wolf population in the restricted area: the results of the Princeton research team, summarized in a press release from “The Society for Integrative & Comparative Biology”, show that the wolf population there differs from that outside the radiation-contaminated area area. area. Scientists led by evolutionary biologist Cara Love began their research in 2014, when they collared some wolves to collect real-time data on their location and radiation exposure. Blood samples were also taken from the animals.
Wolves are particularly suitable as test subjects because, as top predators, they are at the top of the food chain. Normally this is a privileged position in an ecosystem, but in an area like the Radioactive Exclusion Zone this is reversed. Radiation exposure increases from bottom to top in the food pyramid: plants grow on contaminated soil, herbivores eat these plants and are in turn eaten by carnivores. Radioactive materials therefore accumulate at the top of the pyramid.
This circumstance could indicate that radiation exposure is particularly severe for wolves and that their population is therefore smaller than in comparable areas that are not radioactively contaminated. As Love reports, this is by no means the case: she told US radio station NPR that the wolf population in the exclusion zone is seven times denser than in nature reserves in neighboring Belarus.
According to the results of the study, wolves in the exclusion zone are exposed to radiation of up to 0.1128 millisieverts every day. Calculated per year, this is more than 41 millisieverts (mSv). Sievert (Sv) is the unit of measurement for radiation exposure due to ionizing radiation, which, for example, influences the risk of cancer. For comparison, the legal limit for exposure to radiation from nuclear facilities in Switzerland is 1 mSv per year. The natural background radiation to which a person on the ground is exposed is 2 to 3 mSv per year. If you add other exposures, such as those caused by flights or X-rays, you get about 6 mSv per year in Switzerland.
Researchers found that the Chernobyl wolves had an immune system similar to that of cancer patients undergoing radiation therapy. Most importantly, they were able to identify certain parts of the wolf genome that increase the chance of surviving cancer.
According to Love, the reason for wolves’ greater resistance to cancer is that wolves are subject to rapid natural selection, likely driven by equally rapid changes in their environment. Radioactive radiation is a mutagenic factor, which means that it is a physical influence that increases the mutation rate in the genetic material; mutations occur more frequently than would normally be expected. Most mutations are harmful or have no effect, but there are some that can be beneficial in a certain environment.
The radiation had caused some wolves in the exclusion zone to mutate genetic material that made them more resistant to cancer than other wolves. Although they still developed cancer at the same rate as their peers, they were able to resist the disease so well that they were able to pass on their genes to the next generation. This caused the mutation to spread throughout the zone’s wolf population.
According to the data from the study, the cancer resistance of the mutant Chernobyl wolves clearly has a genetic cause. But the researchers themselves point out that there are even more factors on which the health and resilience of animals depend. One of those factors is that the animals in the exclusion zone are almost completely free from human influence, partly through hunting, forestry and agriculture. These influences often act as stressors that negatively impact the health of the affected animals.
Love points out that much of the research to date has focused on mutations that increase the risk of cancer. She now wants to determine exactly which protective mutations in the wolf genome increase the chance of surviving cancer. And she hopes that the findings from studying the wolf genome could help human cancer patients or people at risk for cancer in the future. The way these canines develop cancer is similar to that in humans.
The research team is now working with cancer specialists to find out how these findings could impact human health. However, research work on site in the exclusion zone currently has to be suspended – first the corona pandemic thwarted the scientists’ plans, then the Russian war of aggression against Ukraine made any research activity there impossible.
source: watson
I’m Maxine Reitz, a journalist and news writer at 24 Instant News. I specialize in health-related topics and have written hundreds of articles on the subject. My work has been featured in leading publications such as The New York Times, The Guardian, and Healthline. As an experienced professional in the industry, I have consistently demonstrated an ability to develop compelling stories that engage readers.
