It was believed that the Chernobyl nuclear accident was largely responsible but the new study shows it is nuclear tests from 60 to 80 years ago that have kept them contaminated.
The shaggy-haired, tusked pigs roam free in the woods of Germany and Austria but because they root out truffles and other food to eat from polluted soil their levels are still high.
In contrast, other animals affected by Chernobyl have much lower levels than the pigs, whose radioactive caesium levels render their meat unsafe to eat.
Radioactive caesium is a byproduct of nuclear weapons explosions and nuclear energy production.
It poses risks to public health when it enters the environment and Europe got a large dose of radioactive caesium contamination following the Chernobyl power plant accident in 1986, 37 years ago.
Whilst caesium-137 has declined in most game animals since then, the levels of contamination in wild pigs has remained more or less the same.
This has resulted in their meat continuing to exceed regulatory limits for consumption, a drop in hunting and an overpopulation of the animals in Europe.
This led researchers from Technische University in Vienna and Leibniz University in Hannover to investigate why the radioactive levels haven’t fallen.
They found that the pigs still had high levels of caesium-135, a much longer-lived form produced during nuclear fission.
The team worked with hunters to collect wild boar meat from across Southern Germany and then measured the caesium-137 levels with a gamma-ray detector.
To determine the origin of the radioactivity, the team compared the amount of caesium-135 to cesium-137 with a sophisticated mass spectrometer.
A high ratio points to nuclear weapons explosions, whereas a low ratio implicates nuclear reactors.
They found that 88 percent of the 48 meat samples exceeded German regulatory limits for radioactive caesium in food, according to the study published in the journal Environmental Science & Technology.
For the samples with elevated levels, the researchers calculated the ratios of caesium-135 to cesium-137, and found that nuclear weapons testing supplied between 10 and 68 per cent of the contamination.
In some samples, the amount of caesium from weapons alone exceeded regulatory limits.
Study author Dr. Georg Steinhauser from Technische University said: “Some of our samples from 2019 to 2021 exceed the regulatory limits by a factor of up to 25.
Dr. Bin Feng from Leibniz University added: “With the intensifying war between Ukraine and Russia, much concern has been expressed about the terrible consequences of a nuclear war or a combat-triggered nuclear accident.
Produced in association with SWNS Talker