Radioactive contamination of edible mushrooms (as of 2021, measured values 2018 to 2020)

About 35 years after the Chernobyl reactor accident, elevated activity levels of the radionuclide cesium-137 (Cs-137) can be measured in some species of edible wild mushrooms in some parts of Bavaria. Some mushroom species can still contain up to a few thousand becquerels (Bq) Cs-137 per kilogram (kg) fresh mass. The Federal Office for Radiation Protection (Bundesamt für Strahlenschutz, BfS) has been investigating the radioactive contamination of wild mushrooms with radiocaesium in southern Germany since 1987. This area was heavily contaminated by the Chernobyl reactor accident, showing Cs-137 activity levels between 2,000 and 50,000 Bq per square meter and local hot spots with more than 100,000 Bq per square meter. The measured values for wild mushrooms vary greatly depending on sampling area and mushroom species. Measured values exceeding 1,000 Bq Cs-137 per kg fresh mass were detected in samples of Hydnum repandum, Hydnum rufescens, various Hygrophorus species, Cantharellus tubaeformis, Xerocomellus chrysenteron, Imleria badia, Lactarius lignyotus, Russula ochroleuca, Cortinarius caperatus, Tricholoma columbetta, Laccaria amethystina, Hygrophorus agathosmus and Xerocomus subtomentosus in the period from 2018 to 2020. As a rule of thumb, the intake of 80,000 Bq Cs-137 via food results in a radiation exposure of adults of about 1 millisievert (mSv). A meal of 200 grams (g) of Imleria badia with 2,100 Bq Cs-137 per kg fresh mass (the highest activity measured in Imleria badia in the last three years) once a week throughout the whole year, for example, will cause an additional radiation exposure of about 0.27 mSv per year, referred to as ingestion dose. This is a little bit more than a tenth of the mean annual radiation exposure due to natural sources in Germany (2.1 mSv). Mushrooms with Cs-137 levels exceeding 600 Bq per kg fresh mass are not allowed to be sold on the market in Germany. However, this limit does not apply to private mushroom pickers, who eat the mushrooms themselves. At the same time, BfS advises mushroom pickers in more contaminated areas of Germany to get informed about the Cs-137 content of wild mushrooms. If one would like to keep the personal radiation exposure as low as possible, the regular consumption of self-collected wild mushroom species that are likely to show higher contamination levels from experience should be avoided. The acceptable additional radiation exposure from the consumption of self-collected mushrooms is ultimately a personal decision. The annually published report of BfS on the present contamination situation provides the basis for an informed decision regarding the consumption of self-picked mushrooms.