Shellfish living in streams near the Brunswick Executive Airport were contaminated by the August firefighting foam spill, according to the Maine Department of Environmental Protection.

Tests conducted weeks after a hangar malfunctioned and released thousands of gallons of toxic foam mixed with water into the nearby environment show elevated levels of PFOS — a type of chemical within the per- and polyfluoroalkyl substance family, which are also known as PFAS or “forever chemicals.”

“In summary, the release of firefighting foam greatly increased the concentration of PFOS in fish from the affected parts of Merriconeag Stream and Mare Brook,” the DEP said in a press release. “But as there was already a do-not-eat advisory in place, there is no change for fish consumption advice given these latest data.”

PFOS is a compound known to be harmful to human health and is found in high levels in aqueous film-forming foam (AFFF). Brunswick airport’s Hangar 4, which is owned by the Navy but operated by the Midcoast Regional Redevelopment Authority, dumped 1,450 gallons of AFFF concentrate mixed with 50,000 gallons of water on Aug. 19, 2024, prompting ongoing cleanup and monitoring efforts.

Samples of shellfish were taken three and five weeks after the spill happened, but the agency said tissue testing requires complicated lab protocols. It noted that labs that can do this type of analysis are limited, leading to a several-month turnaround time for results.

Softshell clams, blue mussels and American oysters had PFOS levels higher than the action level — a guideline set for contamination in seafood. In Maine, that action level is limited to 3.5 nanograms per gram.

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Samples from the Merriconeag Stream had PFOS levels ranging from 528–4,687 nanograms per gram. Downstream in Mare Brook, levels ranged from 226–893 nanograms per gram. The agency said it also found low concentrations — 1.5 nanograms per gram — of PFOS in samples collected upstream.

Concentrations were higher three weeks after the spill and then decreased in a sample collected five weeks later, the DEP said. Both samples were still above the tissue action level.

However, contamination is not new in this area.

In August, the Maine Center for Disease Control issued a consumption advisory for fish in Mare Brook and Merriconeag Stream due to PFOS concentrations in trout, black crappies and eels that the Navy collected in 2023. These samples ranged from 28–298 nanograms per gram of PFOS.

The DEP took additional samples in November and expects to have results in by March.

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