“Forever chemicals” are everywhere — water, soil, crops, animals, even in the blood of 97% of Americans — and researchers in the College of Engineering have a theory as to how they got there.

Recent findings suggest that the microbes that break down biodegradable waste are likely complicit in the release of the notorious per- and polyfluoroalkyl substances (PFAS). Once in the environment, the chemicals remain a permanent hazard to human health.

In Environmental Science Processes & Impacts, the group explained how PFAS can leach out of fertilizer made from recycled waste with the help of microbial decomposition.

The research could help to explain how PFAS accumulates in the soil, crops and groundwater. Fertilizer made from treated sewage waste is used widely on farms and residential land.

“We know that microbes exist in biosolid sludge even after the stabilization treatment process, and given the role they play in the decomposition of organic compounds…we wanted to examine how microbial weathering of these organic compounds can impact PFAS leaching potential,” says Associate Professor Christopher Sales, who co-authored the study with doctoral student Asa Lewis.

They collected treated biosolid samples and tested each to determine its initial level of organic matter, proteins, lipids and PFAS. Samples were then placed in an environmentally controlled chamber for three months to undergo microbial activity.

Samples with the highest level of microbial activity also demonstrated the highest level of PFAS partitioning. The results demonstrated this increase is likely due to the microbes breaking down proteins and lipids in the biosolid, which allows the PFAS to spread, or partition, as water passes through.

“This…supports that regulation or advanced treatment in wastewater treatment plants is needed to reduce impacts to the environment,” says Lewis.