Levels of some of the most dangerous Pfas compounds have dramatically fallen in Canadian seabird eggs, according to a new peer-reviewed study. The authors say the findings illustrate how regulations can effectively reduce pollution.
Study Details
Researchers examined Pfas levels in the eggs of northern gannets in the St Lawrence Seaway basin over a 55-year period. Pfas concentrations rose sharply from the 1960s through the peak of the chemicals' use in the late 1990s and early 2000s, then declined significantly.
Raphael Lavoie, a co-author and ecotoxicologist with Environment and Climate Change Canada, described the findings as "good news." He noted: "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. The regulations are having a good effect."
Regulatory Impact
The decline coincides with several regulatory actions. Chemical giant 3M, one of the largest producers of Pfas, began phasing out Pfos, among its most common and toxic compounds, amid regulatory scrutiny. By 2015, major chemical makers reached an agreement with the US Environmental Protection Agency to phase out Pfos and Pfoa, a similarly problematic compound.
Pfas, or per- and polyfluoroalkyl substances, are a class of at least 16,000 chemicals used to make products resistant to water, stains, and heat. They are called "forever chemicals" because they do not break down naturally and are linked to cancer, thyroid disease, kidney problems, and decreased immunity.
Egg Data
Eggs were collected from remote Bonaventure Island, which hosts North America's largest northern gannet colony. Data show Pfos levels fell from a peak of 100 parts per billion (ppb) to 26 ppb by 2024, a 74% drop. Pfoa levels fell about 40% over the same period, though they ticked back up in recent years. PFHxS, another toxic Pfas compound, fell from 0.69 to 0.19 ppb, a drop of about 72%.
Historical Context
Pfas production increased sharply between 1969 and the mid-1990s, driven by widespread use in firefighting foams, stain guards, and manufacturing. Without regulatory oversight, the chemicals accumulated in the environment, exposing wildlife. The St Lawrence River received pollution from manufacturing centers around the Great Lakes, putting northern gannets at high risk.
As dangers became clear, the US, Europe, and Canada increased regulatory pressure. The United Nations targeted Pfos, which was listed in the 2009 Stockholm Convention, requiring signatory countries to restrict its production and use. Militaries and other users of firefighting foam switched to Pfas-free products or stopped using the chemicals in training, significantly reducing water pollution.
Ongoing Concerns
However, not all news is positive. Chemical makers have moved to newer, smaller Pfas compounds that also pose environmental and health risks. Levels of these compounds have likely increased, though they are harder to measure in bird eggs because they do not accumulate as much in wildlife, Lavoie said.
Moreover, compounds like Pfos persist in the environment and animals' bodies for decades. The authors emphasize the need for continued scientific and regulatory vigilance, as contamination will remain for the foreseeable future.
