Concentrations of some of the most toxic PFAS compounds have fallen dramatically in the eggs of northern gannets nesting along Canada’s St. Lawrence Seaway — and a new peer-reviewed study says the decline is direct evidence that chemical regulations work.
At a glance
- Northern gannet eggs: Researchers tracked PFAS levels in eggs collected from Bonaventure Island, home to North America’s largest northern gannet colony, over a 55-year period ending in 2024 C.E.
- PFOS decline: Concentrations of PFOS — one of the most toxic and widely used PFAS compounds — fell from a peak of 100 parts per billion to 26 ppb, a 74% drop.
- Regulatory impact: The decline closely tracks a series of national and international restrictions on PFAS production, including a 2009 C.E. listing under the Stockholm Convention and a 2015 C.E. phase-out agreement with the U.S. Environmental Protection Agency.
What the eggs revealed
Bird eggs are among the most reliable environmental records scientists have. Because seabirds sit near the top of marine food chains, contaminants accumulate in their tissues — and in their eggs — at concentrations that reflect pollution across an entire ecosystem.
Raphael Lavoie, an ecotoxicologist with Environment and Climate Change Canada and a co-author of the study, described the pattern the data revealed as striking. PFAS levels climbed steeply through the 1960s, peaked in the late 1990s and early 2000s at concentrations that crossed toxicological risk thresholds for the birds, then fell steadily.
“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,” Lavoie said. “The regulations are having a good effect.”
How regulations turned the tide
PFAS — short for per- and polyfluoroalkyl substances — are a class of at least 16,000 synthetic chemicals used to make products resist water, stains, and heat. They are called “forever chemicals” because they do not break down naturally, and they are linked to cancer, thyroid disease, kidney problems, and reduced immunity.
Production surged between 1969 C.E. and the mid-1990s C.E., driven by firefighting foams, stain-resistant coatings, and industrial manufacturing — much of it concentrated around the Great Lakes, whose runoff flows into the St. Lawrence. With almost no regulatory oversight, the chemicals accumulated rapidly in the ecosystem.
The turnaround began when 3M, one of the largest PFAS producers, started moving away from PFOS under regulatory scrutiny in the early 2000s C.E. That shift, combined with the 2009 C.E. Stockholm Convention listing of PFOS — which requires signatory nations to restrict its production — and a 2015 C.E. agreement with the U.S. EPA to phase out both PFOS and PFOA, helped bend the curve. Militaries and industrial users also switched to PFAS-free firefighting foams or stopped using the chemicals in training exercises, significantly cutting water pollution.
By 2024 C.E., PFOS in the gannet eggs had fallen 74%. PFHxS, another toxic compound, dropped about 72%, from 0.69 ppb to 0.19 ppb. PFOA levels fell roughly 40%, though they edged back up in recent years — a detail worth watching.
The work that remains
The study is not an all-clear. Chemical manufacturers responded to restrictions on legacy PFAS by shifting production to a newer generation of shorter-chain compounds, which also pose environmental and health risks. Those newer chemicals are harder to detect in bird eggs because they do not accumulate in wildlife tissue as readily, making surveillance more difficult.
Long-lived compounds like PFOS also persist in bodies and sediments for decades, meaning the birds and the broader St. Lawrence ecosystem will carry contamination well into the future. The authors write that this “emphasizes the importance of maintaining scientific and regulatory vigilance.”
The Environment and Climate Change Canada team’s findings arrive at a moment when PFAS regulation is under renewed pressure in several countries. In the U.S., EPA drinking water limits for PFAS established in 2024 C.E. face legal and political challenges. In Europe, a broad proposal to restrict all non-essential PFAS uses is moving through regulatory channels, with a decision expected in the coming years.
Why this matters beyond seabirds
Northern gannets are not just a conservation symbol — they are a measuring instrument. Their eggs encode the chemical history of an entire watershed, and the 55-year record Lavoie and colleagues assembled is one of the longest continuous PFAS datasets for any wildlife species.
The story that record tells is one of cause and effect: chemicals rose when production was unregulated, peaked when exposure was highest, and fell when governments acted. That arc is not common in environmental science, where human interventions often take decades to show measurable results — if they show them at all.
The international effort to reduce persistent toxic chemicals has been slow and contested, and next-generation PFAS remain a serious open question. But in the eggs of one seabird colony on a remote Canadian island, there is now a documented, quantified record of what regulation can do.
Read more
For more on this story, see: The Guardian
For more from Good News for Humankind, see:
- U.K. cancer death rates fall to their lowest level on record
- Renewables now make up at least 49% of global power capacity
- The Good News for Humankind archive on environmental health
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