Environment| Environment

The Maine Center for Disease Control and Prevention is considering whether to impose stricter standards and issue warnings about PFAS in freshwater fish. This decision will better reflect the most recent science. The state CDC does not regulate seafood products. The U.S. Food and Drug Administration has not yet provided any guidance regarding safe levels of PFAS in shellfish and other seafood.

State consumption advisories would likely be similar to those in place for mercury levels freshwater species in Maine lakes and rivers. These warnings would not apply to seafood that has been caught in the ocean, or in grocery stores.

PFAS is a group of over 4,000 chemicals that has been used in household and industrial products since the 1950s, such as firefighting foam and waterproofing. PFAS exposure can increase the risk for kidney and testicular cancers, lead to high bloodpressure or pre-eclampsia among pregnant women, and cause changes in liver enzymes that can affect children’s ability to respond to vaccinations.

The Maine CDC establishes thresholds or “action levels” that it will consider issuing a consumption advisor for recreationally caught freshwater fish. It has increased the level of perfluorooctane sulfonate (PFOS), which is the most widely studied and researched of these compounds, to 34 parts/billion over the years.

Andy Smith, State Toxicologist, said that he and his team are currently working to adjust the PFOS action level to “about ten times less than it’s now.” This is based on toxicology data from the federal Agency for Toxic Substances and Disease Registry. The PFOS toxicity value was set at 2 nanograms per kg per day.

The Maine Department of Environmental Protection would reduce the action level to 3-4 ppb. This would allow many of the samples it has collected to be above the hazard threshold. According to Tom Danielson (DEP Aquatic Toxicologist), the average concentrations for more than half of the sites or species sampled in 2019/2020 were higher than 4 ppb.

Maine CDC has a fish consumption advisory due to mercury. Pregnant and nursing mothers are advised to not eat freshwater fish from Maine inland waterways. All other people should limit their intake to two meals per week for brook trout and landlocked salmon. Some polluted waterbodies may have more restrictions. Smith stated that Maine CDC would consider whether more restrictive advisories were needed when deciding whether to issue a PFAS-related advisory.

The existence of forever chemicals in Maine fish was first discovered 10 years ago by the U.S. Environmental Protection Agency. They sampled fish from five rivers in Maine as a part of a national survey on urban waterways across the nation and found smallmouth bass that had elevated levels of PFOS in the Androscoggin River, Lisbon, and the Kennebec River, Waterville.

After chemicals were discovered during federal cleanup efforts, scientists from DEP’s Surface Water Ambient Toxics (SWAT) monitoring program began sampling streams around Loring Air Force Base. This site was used for firefighter training activities. The PFOS concentrations in the area were as high as 1,080 ppb. All but one of the samples were above the Maine CDC’s current action level of 42 ppb. This prompted the team of scientists to collect more samples. They searched for potential sources, such as wastewater treatment plants, industrial areas, or downstream of farms where PFAS contaminated sludge might have been spread.

They have found elevated levels of PFOS in fish at various locations downstream industrial sources and wastewater treatment plants on the Mousam Presumpscot, Androscoggin, Kennebec, and Estes lakes since 2014. They also found slightly elevated levels of the chemical in fish in Halfmoon Stream, which is below a Thorndike farm.

Jim Stahlnecker, a biologist at the DEP’s Bureau of Water Quality began to wonder if forever chemicals might be found in shellfish. He had been testing blue mussels to see if they were contaminated with heavy metals, dioxins, and PCBs for the SWAT monitoring program’s marine section. His team began testing mussels, clams and other PFAS-related substances in 2013.

Perfluorooctane Sulfonamide, a water- and oil-repellent paper coating ingredient, was found in mussels at East End Beach, Portland. The team didn’t detect any other compounds, and it also didn’t detect any in mussels from Sears Island in Searsport.

However, the testing method used to measure the PFAS in shellfish samples could not detect concentrations below one-digit parts per million, depending on the compound. Some consumables, such as water, are regulated according to PFAS levels in parts per trillion.

Stahlnecker and his team searched Harpswell Cove in 2014 for blue mussels. This is near the former Brunswick Naval Air Station. Although the mussels were not found as close as they wanted, they were found about halfway down the cove. The samples contained concentrations of PFOSA from 0.68 to 0.80ppb. Later, they sampled softshell shell clams near the station and did not detect any PFOSA chemicals.

Brunswick Citizens for a Safe Environment did more testing in 2020. They tested the marsh species known by ribbed mussels (from the mouth of Mere Creek), close to the area where the clams had been sampled. They found PFOS at concentrations as high as 0.98 parts per million. These concentrations were lower in the cove than in the control samples.

David Page, a Bowdoin College professor in chemistry and biochemistry, wrote a report about the study. He said that it was intended to answer one simple question: Did chemicals associated with activities at Brunswick Naval Air Station migrate offsite and affect biological communities in Harpswell cove.

Page stated, “The answer was unambiguous.” “Partly why we asked the question was that the Navy was reluctant about denying that there were PFAS other than base boundaries. It’s now clear that this is false.

He said that the Navy was inspired by the study to include mussel sampling as part of its monitoring plans for the redeveloped former Naval Air Station.

One of the difficulties with state sampling methods is that different organisms from the same area might collect different chemicals. While the DEP has been sampling the muscle tissue of fish and the shellfish consumed by humans, it may not be giving the full picture.

Dianne Kopec, a research associate at the University of Maine’s Sen. George J. Mitchell Center for Sustainability Solutions has spent her career researching the movement of mercury through aquatic food chains, such as fish to harbor sealings. Now, she is working with a team of researchers to study how PFAS travels between soil, groundwater, and surface water. She hopes to expand her work to study how the chemicals move from organism to organism. The chemicals are also moving to wildlife. Last fall, five Fairfield deer meat samples were discovered to have PFOS levels ranging from 37 to 44ppb.

Kopec stated that PFAS chemicals behave differently to mercury and from each other. Some compounds may be collecting in other parts than fish muscle. This could lead to a decrease in the effectiveness of PFAS chemicals on other animals, such as eggs and other predators.

She said that predators eat whole fish and not just muscle tissue.

Another difference to mercury is the fact that PFAS concentrations don’t increase with age and size. Kopec speculates this might be because it may be transferred to eggs in females. PFOS appears higher up the food chain than other chemicals, but she suggested that it could be because other chemical substances transform into it. PFOS is a legacy chemical and has been largely eliminated. However, newer replacement chemicals like PFOSA have been shown to be able to dissolve PFOS into its more persistent form.

Scientists are trying to understand how forever chemicals move between organisms and within the environment. States continue to work towards understanding the risk to humans through consumption.

The state Department of Environmental Services in New Hampshire is teaming up with Dartmouth College scientists to study the potential exposure from recreational shellfish harvesting close to the former Pease Air Force Base. This site also serves as a training ground for firefighters. Megan Romano, an environment epidemiologist, and Celia Chen (an aquatic ecologist) are conducting a survey to gather data on seafood consumption patterns. Their preliminary research shows that consumers of shellfish, from average to frequent, could be exceeding certain PFAS compounds’ minimum risk levels as defined by federal toxic substances registry.

Romano stated that Dr. Chen and he are working on a project where seafood is an underappreciated source for exposure to PFAS.

Stahlnecker and his team expanded their sampling efforts in Maine to find the chemicals in blue mussels. Tests have improved and can now detect concentrations of some compounds as low as 0.02 ppb. The number of compounds that can be detected has increased to 33.

The team collected low levels of about 10 compounds from mussels at 24 sites close to potential sources. In 2019, and 2020, the most common was PFOSA. It was present at the detection limit in some areas along the coast. However, it was highest in the western Casco Bay Portland area, the lower Kennebec River, as well as one site in Penobscot River.

Stahlnecker stated that the remaining compounds were not detected correctly. One compound was detected at one location, while another compound was detected at another. Sometimes, they were even right at the detection limit.

He stated, “The take-home message is that we know there are PFAS.” “It’s all around the place, at very low levels.”

They found PFOS, the most common compound in freshwater fish, only in one area: the highly industrialized estuary for the Fore River in Portland. This area is closed to shellfish harvesting as it is close to wastewater treatment plants. In five years of sampling, this was the first time DEP had detected the compound in shellfish. The highest concentration was 0.45 ppb.

Stahlnecker stated, “But it’s hard to know what to compare it to.” Maine CDC’s current fish tissue level of 34 ppb doesn’t offer any direct guidance on seafood.

“We’re not talking about finfish, we’re talking shellfish, and marine waters not fresh and the biggest thing is the intake,” he stated. If you live near a camp or pond and catch bass, you might be able to eat one every two weeks. This will affect how often you can take it in. You can only take it in a lower amount if you take it in regularly.

Smith, a state toxicologist, said that while the Maine CDC can develop action levels for certain marine species at the request of Department of Marine Resources (DMR), it has not done so for PFAS in shellfish or marine fish.

DEP scientists continue their testing efforts as regulators gather more information. Stahlnecker will be partnering with the marine resource department to expand sampling to include other marine species like lobster, pollock and striped bass.

He stated that while we generate this data (which can also be used by others for the development of advisories), we don’t give advice or tell people what to go. “We are trying to figure out what is out there.”

Romano, a researcher who has spent a lot time studying exposure to combinations, believes that PFAS chemical consumption guidelines must be set in combination.

She stated that there are more than 4,000-5,000 of these PFAs. “More then 1,000 are used in industrial applications so we’re likely be exposed to them every day. They are too numerous to be regulated one at a time.

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