Research suggests mushrooms can convert pesticides and herbicides to more innocuous compounds, remove heavy metals from brownfield sites, and break down plastic. Research suggests mushrooms can convert pesticides and herbicides to more innocuous compounds, remove heavy metals from brownfield sites, and break down plastic. In other words, they “digest” whatever substrate, or surface, they’re growing on, converting it to nutrients and—depending on the substrate—edible mushrooms. “In nature, mushrooms break down all kinds of substances, and we’re just beginning to look at this more closely in the lab and in field studies,” she says. “I tell people that the first thing we have to do is find mushrooms that break down the stuff we want to break down.