If there are heavy metals in the environment,

mushrooms are the plants to absorb those( even in air) more than any other plants.  But if your environment is clean of heavy metals ( acceptable level), then should be ok. But how do you know for sure?

I would definitely not eat any mushrooms from China, i know how bad the whole environment pullution and contamination are over there (air, water & soil).

Heavy metals are well known for damaging DNA.