Levels of 'forever chemicals' in Canadian seabird eggs drop sharply due to strict regulations

A new study published in a specialist journal shows that levels of some of the most dangerous PFAS compounds in Canadian seabird eggs have dropped sharply, which the authors see as evidence of the effectiveness of legal regulations.

Scientists analyzed PFAS levels in eggs of the northern gannet in the St. Lawrence River basin over 55 years. The results show that PFAS concentrations soared from the 1960s, peaked in the late 1990s and early 2000s, and then began to decline.

This decline coincided with several important changes: under regulatory pressure, chemical giant 3M—one of the largest PFAS producers—began phasing out PFOS, one of the most common and toxic compounds. By 2015, major chemical manufacturers reached an agreement with the U.S. Environmental Protection Agency (EPA) to phase out PFOS and PFOA.

Raphael Lavoie, co-author of the study and an ecotoxicologist at Environment and Climate Change Canada, called this "good news." He said: "We saw an incredible increase to a peak where concentrations exceeded toxic thresholds for this bird, then a very positive sharp drop. The regulations are working well."

PFAS are a group of at least 16,000 chemicals commonly used to make water-resistant, stain-resistant, and heat-resistant products. They are called "forever chemicals" because they do not break down naturally, and they have been linked to health problems including cancer, thyroid disease, kidney issues and immune suppression.

Bird eggs were collected from remote Bonaventure Island, home to the largest northern gannet colony in North America. The data show that PFOS levels in eggs dropped from a peak of 100 ppb (parts per billion) to 26 ppb in 2024, a 74% decrease. PFOA levels fell by about 40% over the same period, though they rose slightly in recent years. Meanwhile, PFHxS—another common PFAS compound—dropped from 0.69 ppb to 0.19 ppb, a 72% decline.

The paper details that PFAS production surged from 1969 to the mid-1990s, driven by applications from firefighting foam to stain repellents and various manufacturing processes. With almost no regulatory oversight, these chemicals quickly built up in the environment, exposing wildlife like the northern gannet. This bird faces high risk because the St. Lawrence River receives polluted water from industrial manufacturing hubs in the Upper Midwest around the Great Lakes. Chemical levels in eggs reached concentrations indicating ecotoxic risk, according to Lavoie.

As the dangers of common PFAS became better understood, the U.S., Europe and Canada all increased regulatory pressure with proposed rules or risk actions. The United Nations also added PFOS to the Stockholm Convention in 2009, requiring signatory countries to restrict production and use. In recent decades, the military and firefighting foam users have switched to PFAS-free products or stopped using foam in training exercises, significantly cutting water contamination.

However, not all is good news. Chemical manufacturers have switched to newer, smaller-molecule PFAS, and these compounds also pose risks to the environment and wildlife. Levels of these new compounds may have increased, and the study found one example of such a shift, but the newer PFAS 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 or animal bodies for decades, so birds and the environment will continue to be polluted for the foreseeable future. The study authors emphasize "the importance of maintaining scientific and regulatory vigilance."