The reasons are still unclear
Even three decades after the Chernobyl nuclear disaster, some forest mushrooms in some areas are still radioactive. However, this does not apply to one of the most expensive delicacies in the world: truffles can obviously be eaten without hesitation - at least if they come from less affected regions. Together with German colleagues, Swiss scientists examined 82 Burgundy truffles from Western Europe, which were collected from 2010 to 2014 with the help of trained truffle dogs. The noble mushrooms came from various natural deposits and plantations in Switzerland, Germany, France, Italy and Hungary.
After the Chernobyl nuclear disaster in 1986, wind and rain distributed significant amounts of radioactive particles, especially cesium 137 (137Cs), across the European continent. In many areas, the top layer of forest soil is still contaminated. Fungi absorb these particles. Deer truffles of the genus Elaphomyces, also known as "false truffles", are among the most radioactive mushrooms. They are often eaten by roe deer and wild boar, so that the game meat also shows too high cesium values in some severely affected regions.
In the case of the Burgundy truffle (Tuber aestivum), the samples showed only negligible radioactivity. The 137Cs values were below the detection limit of 2 becquerels per kilogram. The limit for mushrooms is 600 becquerels per kilogram. So far it is unclear why the subterranean tube fungi are not very susceptible to the absorption of radioactivity. It is probably due to the mechanisms of nutrient extraction from the humus, which are to be explained in more detail. The Burgundy truffle prefers lime-rich soils, and calcium carbonate could reduce the absorption of radioactive cesium. Other possible factors are the depth of the fungal network and the lack of 137Cs-binding pigments.
The question remains whether the all-clear applies to the Burgundy truffle in general. Most of the truffles examined come from less affected regions. Nothing can be said about the radioactive contamination of truffles from more severely affected areas such as Belarus, northern Ukraine or central Austria. The investigations should therefore also be extended to other regions. (Heike Kreutz, aid)