Thirty years ago, when the Chernobyl disaster rained radioactive isotopes of plutonium, cesium, and strontium on the surrounding Red Forest, hundreds of acres of trees died within days. Today, some hot spots are still 100 times more radioactive than normal. But the Chernobyl Exclusion Zone no longer looks like a wasteland—and a new study suggests that some wildlife is thriving there.
In large part, that's because humans are gone: because of the dangers of the fallout, people were evacuated from an area larger than 600 square miles. Many of the 250 communities that were emptied were also bulldozed to the ground. And the some of the animals that were dwindling before the accident—wolves, foxes, boars—seem to have increased in number, despite the fact that they were living with radiation.
It became an accidental (and less than ideal) nature reserve. "It is well established that many large mammals, and large carnivores in particular, generally thrive when provided sufficiently large areas of land where they are buffered from the pressures of human activity, especially the loss and degradation of habitat," says James Beasley, of the University of Georgia researchers who led the study.
Before the disaster, some animals were hunted, and others lived in fragmented habitats, disturbed by farming, forestry, and human settlements. Now, without those pressures, they've come back. In the new study, the researchers set up remote cameras at 94 sites within the exclusion zone, added scents to attract carnivores, and counted the animals who came by over five weeks. Even in the areas that are still extremely contaminated, there were large populations of wildlife.
"Collectively these data suggest the exclusion zone can support abundant and self-sustaining populations of a multitude of species," says Beasley. "However, it is important to note that these studies don't suggest radiation is good for wildlife. Rather, that the effects of everyday human activities are worse for many species of wildlife than any potential effects of radiation."
Another team of researchers, who have been traveling to the area for 15 years, have published studies documenting some of those effects: some animals developed tumors and other abnormalities, while others showed decreased fertility and shorter lifespans. (Some of these findings, however, have been controversial, and disputed by other researchers.) They also found fewer animals in the most radioactive areas.
"When you look at the less radioactive areas, the clean areas that are inside the zone, and they're vast areas that are populated, things seem to be relatively normal there," says one of the researchers, Timothy Mousseau from the University of South Carolina. "It's when you start to focus in on those more radioactive areas that you see there is this decline in numbers."
Mousseau found similar effects in Fukushima. "In terms of birds, there are very strong drop-offs in numbers of birds in more radioactive areas," he says. "It's really kind of eerie—when you pay attention to these things, when you go from a relatively clean area, everything seems pretty normal, the birds are flying around and singing, and 20 miles up the road in a hot place, there's no birds. It's quiet. There's very few butterflies."
Still, the new study, along with another published in 2015, finds the opposite, at least for larger mammals. It's not clear if the animals are as healthy as normal—but their populations seem to be. And there's no noticeable difference in populations between the most and least contaminated areas.
"Without doubt, extremely high doses of radiation exposure can cause genetic damage," says Beasley. "But our data, combined with recent studies, suggest any potential negative effects to individuals are not sufficient to cause population-level declines in mammals inhabiting the exclusion zone."
Perhaps the same is true for animals farther away. The fallout from Chernobyl traveled as far as Scandinavia, and Germany; now, it's possible to find herds of radioactive reindeer in Norway and radioactive wild boars in Germany. Reindeer like to eat lichens and boars like to eat mushrooms, both foods that are heavily contaminated; now, when the animals are hunted, they're often too radioactive for humans to safely eat. (At Chernobyl, milk from a nearby farm was also found to be radioactive in a recent lab test.)
The researchers behind the new study say that more research is needed to better understand the long-term effects of chronic exposure to radiation. Those effects will continue for a very long time: Even though this year marks the half-life of cesium-137 in Chernobyl (the amount left in the area has dropped by half since the accident), there will continue to be radiation in the area for centuries. Plutonium in the area is decaying into a more toxic isotope—americium-241—so in some ways, the zone is actually becoming more contaminated over time.
"Over the last three decades Chernobyl has served as an important living laboratory in which scientists can better understand effects of chronic radiation exposure on organisms," says Beasley. "While these studies have greatly advanced our understanding of the effects of radiation exposure on biota, this remains an important area of research, and so Chernobyl undoubtedly will serve as an important system to study radiation effects for decades to come."