Wild mushrooms can absorb radioactive elements from soil, particularly polonium and radium which accumulate to high levels. The amount of radioactivity varies greatly depending on where mushrooms are grown and what species they are. In most areas, naturally occurring radioactive elements are the main concern, but mushrooms from regions affected by nuclear accidents like Chernobyl may contain dangerous artificial radioactive isotopes. People who frequently consume wild mushrooms from certain regions could potentially exceed safe annual radiation exposure limits.