If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.


Persistent Pollutants

To prevent PFAS dispersal, Maine bans agricultural use of sludge

Biosolids spread on farmland across US

by Cheryl Hogue
April 21, 2022 | A version of this story appeared in Volume 100, Issue 14


Biosolids in a dump truck are loaded into a spreader hitched to a farm tractor.
Credit: Dana Kolpin/US Geological Survey
Biosolids transferred from wastewater treatment plants to farm fields as fertilizer may contain per- and polyfluoroalkyl substances.

To prevent additional contamination by per- and polyfluoroalkyl substances (PFAS), Maine is set to become the first US state to prohibit the use of municipal and industrial sludge as fertilizer.

Application of PFAS-tainted sludge to agricultural fields in the state has caused contamination that polluted drinking-water wells and led some farmers to euthanize dairy cows and shut down organic vegetable production. Maine governor Janet T. Mills (D) is expected to sign legislation (LD 1911) in late April that would ban application of the material as fertilizer.

PFAS are a family of environmentally persistent synthetic compounds widely used in products such as firefighting foams and grease- and water-resistant coatings for paper. Some of these substances are toxic, including those found in tainted soils and wells in Maine.

The chemicals are carried in industrial and municipal wastewater to sewage treatment plants. They are not broken down by wastewater treatment, which primarily filters out organic solids before discharging water into rivers or lakes.

PFAS persist in those solids, even if the material is composted before it is spread on land. Crops can take up the substances from the soil, and water percolating through the soil can move PFAS into groundwater.

“We must do all that we can to stop further contamination and limit exposure to these toxic chemicals,” Maine state senator Rick Bennett (R), a lead cosponsor of the legislation, says in a statement.

While Maine is the first state to halt use of biosolids as fertilizer, other states could have unrecognized PFAS pollution resulting from this practice, according to the Environmental Working Group (EWG), an advocacy organization. It estimates that sewage sludge is applied to 5% of all US crop fields. The EWG points out that there are no national requirements to test biosolids for PFAS or to warn farmers that biosolids they use as fertilizer could be tainted with these chemicals.

The EWG used data that states reported to the US Environmental Protection Agency as the basis of its estimate.



This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.