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 non-profit Radiation Effects Research Foundation said that people should not overreact, because there are no reports known of health problems with these levels of radiation. On 31 October 2011 a scientist from the Worcester Polytechnic Institute, Marco Kaltofen, presented his findings on the releases of radioactive isotopes from the Fukushima accidents at the annual meeting of the American Public Health Association (APHA). Airborne dust contaminated with radioactive particles was released from the reactors into the air. This dust was found in Japanese car filters: they contained caesium-134 and caesium-137, and cobalt at levels as high as 3 nCi total activity