Cortinarius caperatus found to be infested with maggots when picked. Mycologist David Arora recommends discarding the tough stipes. The popularity of "C. caperatus" across Europe has led to safety concerns related to its propensity to accumulate contaminants. Fungi are very efficient at absorbing radioactive isotopes of caesium from the soil and naturally have trace amounts of the element. Caesium may take the place of potassium, which exists in high concentrations in mushrooms. "C. caperatus" bioaccumulates radioactive caesium Cs—a product of nuclear testing—much more than many other mushroom species. Levels dramatically rose after the 1986 Chernobyl disaster. This is a potential health issue
Radiation effects from the Fukushima Daiichi nuclear disaster from the Fukushima plant. Rain accumulated the caesium in the soil. Measured radioactivity per kilogram reached 250 becquerels in eastern Hokkaido, and 25 becquerels in the mountains of western Japan. According to the research group, these levels were not high enough to require decontamination. Professor Tetsuzo Yasunari of the University of Nagoya called for a national soil-testing program because of the nationwide spread of radioactive material, and suggested identified hotspots, places with high radiation levels, should be marked with warning signs. The first study concentrated on caesium-137. Around the nuclear plant, places were found containing up to 40.000 becquerels/kg, 8