Wild boars in Europe can’t shake off their radioactivity

High levels of radioactivity have been found in Europe’s wild pigs for decades – and scientists believe they now know exactly how and why they came to be contaminated.

“Deranged packs of radioactive pigs” have been “wreaking havoc” in central Europe, said The Daily Beast. The high levels of caesium-137 found in wild boars in Bavaria, southeast Germany, have long been linked to the 1986 Chernobyl nuclear disaster.

Yet while radiation levels have decreased in other animals across Europe since then, experts have wondered why that decline did not occur in the pigs, a phenomenon that has become known as the “wild boar paradox”.

Subscribe to The Week

Escape your echo chamber. Get the facts behind the news, plus analysis from multiple perspectives.

SUBSCRIBE & SAVE

Sign up for The Week's Free Newsletters

From our morning news briefing to a weekly Good News Newsletter, get the best of The Week delivered directly to your inbox.

From our morning news briefing to a weekly Good News Newsletter, get the best of The Week delivered directly to your inbox.

Sign up

But according to a newly published study in the Environmental Science & Technology journal, the source of their contamination may be linked to atmospheric weapons testing that took place in the 1950s and 1960s.

The researchers used a “relatively new method of analysis” involving the ratio of two caesium isotopes to analyse the carcasses of boars killed by hunters across Bavaria from 2019 to 2021, explained The New York Times.

Nuclear reactors and nuclear weapons leave slightly different contamination signatures, “with distinct ratios of cesium-135 to cesium-137 isotopes”. So researchers could determine that the radiation present in the boars stemmed from nuclear testing conducted decades ago.

Georg Steinhauser, a radiochemist at the Vienna University of Technology and co-author of the study, explained that it was impossible to attribute the nuclear weapons fallout to any particular location or weapons test, as they affected the entire northern hemisphere evenly.

After a nuclear explosion “an enormous updraft occurs”, which pushes the radioactive material higher. When this falls back to Earth, the material has evenly distributed higher in the atmosphere to create a truly “global fallout” phenomenon, he told The Washington Post.

As for exactly why wild pigs are more radioactive than other animals, and how they came into contact with radioactive isotopes, the answer lies in their food. The boars are likely to have consumed caesium from contaminated deer truffle mushrooms, said Steinhauser.

Deer truffles, which sit some 20-40cm deep into the soil, appear to have absorbed all the caesium from nuclear weapons testing six decades ago. But caesium from the Chernobyl disaster is yet to reach the depths of the deer truffles, meaning radioactivity levels could increase even further.

Those who enjoy eating wild boar, however, shouldn’t be too concerned. Steinhauser said humans would have to eat “insane” amounts of boar to come into contact with meaningful amounts of radioactive material.