Soil fungi broke down the toxic wood preservative pentachlorophenol (PCP) at 5–15 mg/L, chemically converting it into much less harmful compounds like tetrachlorophenol, hydroquinone, and maleylacetate. More than 80% of tested forest fungi (mostly Ascomycota) transformed or completely destroyed PCP within about 14 days, showing they actively strip chlorine atoms and detoxify the chemical instead of just trapping it.