The secret of the high radiation levels of boars in forests in Germany and Austria has been revealed as direct result of nuclear bomb testing more than half a century ago.
The boars contain unsafe radioactive cesium - a liquid metal - and so are dangerous for humans to eat, according to research by the Vienna University of Technology.
The shaggy, tusked pigs roaming around the forests were thought to have only been made radioactive by the 1986 Chernobyl accident.
However, Oppenheimer-style nuclear weapons testing is also responsible for their long-lasting radioactivity.
“We were stunned to see that the nuclear weapons fallout still impacts the ecosystem to such great extent”, the paper’s corresponding authors Dr Georg Steinhauser and Dr Bin Feng told BBC Science Focus.
When nuclear weapons explode or nuclear energy is produced, radioactive cesium is created.
When it enters the environment, it can threaten human health – and did just this when the Chernobyl power plant exploded in Ukraine almost four decades ago.
But the study, published in the journal Environmental Science & Technology, shows that the radioactive contamination affecting the boars was also caused by atmospheric nuclear weapons testing by nations across the world in the 1950s and 1960s.
Both events contaminated the radioactive boars’ food sources, including underground truffles.
Cesium-137 used to be present in other game animals, but these levels have dropped.
However, the boars are plagued by cesium-135, a form of the radioactive metal whose imapct lasts longer.
The researchers knew that detecting a higher ratio of -135 than -137 would indicate more fallout from nuclear weapons explosions rather than nuclear reactors – and that’s what they found.
Across the samples up to 68 per cent of the contamination came from nuclear weapons testing.
Eighty-eight per cent of the meat samples exceeded safe levels of radioactivity in food. L
ess hunting of these animals due to food safety issues has contributed to their overpopulation in Europe.
“It is a cautionary tale that the long-forgotten atmospheric nuclear weapons tests and their fallout still cast a shadow on the environment,” Steinhauser and Feng told BBC Science Focus.
“Just because they took place 60 years ago doesn’t mean that they no longer impact the ecosystem.”