Dozens of environmental organizations hope that the discharge of PFAS and microplastics into Boston Harbor will be better monitored in the near future.

More than 40 groups are calling on the EPA to require the Deer Island wastewater treatment plant to better regulate the discharge of the so-called “forever chemicals” and microplastics, saying that the plant is one of the largest sources of these contaminants in the country.

"The treatment process at Deer Island, and across the country, is not designed to remove chemicals of emerging concern like PFAS or contaminants like microplastics," said Laura Orlando of the environmental advocacy group Just Zero, which led drafting the letter. "But these contaminants concentrate in the wastewater treatment plant."

Deer Island, which is run by the Massachusetts Water Resources Authority, or MWRA, treats about 360 million gallons of sewage a day and discharges it into the Harbor. While it removes many pollutants, the environmental groups say there's no treatment done to remove PFAS or microplastics.

Sewage sludge from Deer Island is also turned into fertilizer that's sold for gardens and farms.

“One of the scariest things about this situation is that Deer Island is not an outlier,” John Hocevar of Greenpeace, which also signed on to the letter, said in a press release. “There are over 16,000 wastewater treatment plants in the country, and all of them are releasing dangerous levels of microplastics and PFAS in our oceans and rivers. EPA needs to take action now.”

PFAS chemicals have been linked to serious health problems, including some forms of cancer.

The groups highlight several new requirements they'd like to see the EPA put in place to limit Deer Island from spreading the pollutants. Deer Island is due for new permit from the EPA, and the letter from the groups comes as part of a public comment process on a newly proposed permit.

The groups argue that, if the EPA issues a permit that would continue to let the plant release PFAS and microplastics into the Harbor, it would “fall short of the overarching goal of protecting water quality and public health.”

"The last permit that Deer Island got was in 2000," Orlando said. "And PFAS certainly wasn't on the radar screen, nor were microplastics. But what we found out over the last 20 years, of course, is that wastewater treatment plants are major sources of these pollutants."

Among the regulations the environmental groups are calling for is increased monitoring of PFAS in discharges and an expansion of PFAS chemicals that are tested for. The draft permit includes annual sampling for PFAS, but the environmental groups would like to see that testing happen quarterly.

"What we really want is a picture of what's happening: what's going into the wastewater treatment plant, what's coming out in the treated wastewater and what's coming out in the sewage sludge," Orlando said.

That sewage sludge is turned into dry pellets that the MWRA then sells as fertilizer under the brand name Bay State Fertilizer, which Orlando says raises concerns about the spreading of PFAS contamination. In 2022, Maine became the first state to ban the use of sewage sludge on farms for this reason.

"One of the things that we're asking Deer Island to do is no longer allow for the land application of sewage sludge, no longer allow for the spreading of this toxic material on farms and gardens and parks," Orlando said.

A major PFAS contributor at the plant, Orlando said, is liquid that's drained from landfills, which is called leachate. The letter also asks the EPA to require that leachate to be pretreated — before it goes to Deer Island — to remove or reduce the concentration of PFAS.

In addition, the letter asks for assurance that an independent scientific advisory committee that's been studying wastewater discharge in Massachusetts Bay will be able to continue its research. The draft permit would discontinue the work of the Outfall Monitoring and Science Advisory Panel.

"We don't want that panel to be eliminated," Orlando said. "Because we need them to look at the what's happening in the marine ecosystem with the PFAS and the microplastics and other chemicals of emerging concern that are coming out of the outfall pipe in the Massachusetts Bay."

The MWRA sent its own letter to the EPA regarding the new permit, and highlighted its efforts to remove contaminants from the waste stream.

MWRA spokesperson Sean Navin said in a statement to GBH News that the Quabbin Reservoir, which provides water for millions of Massachusetts residents, does not contain PFAS and that the Deer Island plant is a “passive receiver of PFAS and related chemical compounds.”

"MWRA appreciates that so many of our environmental partners have taken the time to comment on the Deer Island NPDES Permit," Navin wrote. "We all remain very concerned about the levels of PFAS and their impact on our environment. ... We continue to work to find solutions to eliminate PFAS at its source, to keep it out of the waste stream and work to mitigate its impact on our Wastewater system."