BY THE OPTIMIST DAILY EDITORIAL TEAM
Levels of some of the most toxic PFAS compounds have fallen sharply in Canadian seabird eggs, and the reason isn’t complicated. Regulation worked.
A peer-reviewed study tracked PFAS concentrations in the eggs of northern gannets on Bonaventure Island, in the St. Lawrence Seaway basin, over 55 years. PFOS, one of the most common and toxic PFAS compounds, peaked at 100 parts per billion in the eggs, then dropped to 26 parts per billion by 2024, a 74 percent decline. PFHxS, another toxic compound, fell from 0.69 to 0.19 parts per billion, a 72 percent reduction.
“We see this incredible rise to a peak where concentrations seem to be higher than toxicological threshold for those birds, then it really decreases in a nice way,” says Raphael Lavoie, a co-author and ecotoxicologist with Environment and Climate Change Canada. “The regulations are having a good effect.”
What drove the decline
The timeline matches the regulatory record. Under pressure from governments, chemical giant 3M, one of the largest PFAS producers, began moving away from PFOS in the early 2000s. By 2015, major manufacturers agreed with the US Environmental Protection Agency to phase out both PFOS and PFOA. The United Nations targeted PFOS separately, and it was listed under the 2009 Stockholm Convention, which requires member countries to restrict its production and use.
Militaries and other heavy users of firefighting foam switched to PFAS-free products or stopped using the chemicals in training, removing a major source of runoff into waterways.
The gannets were especially exposed. The St. Lawrence Seaway collects runoff from manufacturing centers across the Great Lakes region, and by the late 1990s, PFAS had built up in the birds’ eggs at concentrations that posed genuine ecotoxicological risk.
The caveats
PFOA is down about 40 percent overall but has edged back up in recent years, a reminder that progress isn’t linear.
The larger concern: when regulations squeezed the most problematic PFAS, chemical makers shifted to a newer generation of smaller compounds. These carry their own risks but are harder to detect in wildlife because they don’t accumulate in tissue the same way. Their levels have likely increased, and the study found early evidence of the shift.
PFOS also doesn’t go away. It stays in the environment and in animals’ bodies for decades, meaning contamination continues well after production stops. The study’s authors say this “emphasizes the importance of maintaining scientific and regulatory vigilance.” Read: don’t stop watching.
Why the gannet data matters
PFAS are a class of at least 16,000 chemicals used to resist water, stains, and heat. They don’t break down naturally, which is where the “forever chemicals” label comes from, and they’re linked to cancer, thyroid disease, kidney problems, and immune disruption.
The 55-year gannet record is unusual: it captures the full arc, from the pre-regulatory buildup through the peak and back down. The 74 percent drop in PFOS didn’t happen on its own. It followed bans, phase-outs, international agreements, and purchasing decisions by militaries. The question now is whether governments will do the same with the compounds that replaced PFOS, before those accumulation curves get 55 years to tell their own story.
Source study: Journal of Applied Toxicology— Half a century of per- and polyfluoroalkyl substances in northern gannet eggs: impact of regulations
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