Organic mercury compounds are extremely nasty byproducts of industry. Their badness is largely due to their high bioavailability i.e. they are readily absorbed into our tissues. Inorganic mercury salts, by contrast, tend to have very low bioavailability which limits absorption even in environments with significant background quantities. The toxicity is as much a function of bioavailability as it is presence in the environment. This fungus dramatically changes the bioavailability of mercury compounds in the environment.

There are many highly toxic elements in our environment that are effectively a non-issue due to low bioavailability. In one end and out the other with minimal absorption.