Wild boars in Germany remain radioactive decades after Chernobyl because they eat contaminated truffles.

The 'wild boar puzzle' has long baffled scientists because radiation levels in other forest animals dropped significantly after the 1986 Chernobyl disaster. A 2023 study published in the journal 'Environmental Science & Technology' by researchers from the Vienna University of Technology and Leibniz University Hannover finally explained why. The team analyzed boar meat from 11 locations across Bavaria between 2019 and 2021 using high-precision mass spectrometry.The researchers discovered that the contamination comes from two distinct sources: the Chernobyl accident and atmospheric nuclear weapons testing from the 1950s and 1960s. While Chernobyl contributed the majority of the radiation, up to 68 percent of the cesium in some samples came from older weapons testing. This older radiation had slowly migrated through the soil layers over decades, creating a 'downward migration' effect that only recently concentrated in the deep-growing deer truffles.Deer truffles (Elaphomyces) are a primary food source for boars during the winter when other food is scarce. These fungi act like a sponge for cesium-137, which has a half-life of about 30 years. Because the radioactive material moves downward at a rate of only about one centimeter per year, the truffles are just now absorbing the peak levels of mid-century fallout. This explains why roughly 88 percent of the meat samples tested in Bavaria still exceed the legal safety limits for human consumption.