Half a Century of Per‐ and Polyfluoroalkyl Substances in Northern Gannet Eggs: Impact of Regulations

Per- and polyfluoroalkyl substances (PFAS), known as "forever chemicals", are persistent organic pollutants that have been widely used in the industry across the globe for many decades. Their chemical stability, bioaccumulation, and toxicity pose major environmental and health risks. This study examines temporal trends in the concentrations of 17 PFASs in northern gannet (Morus bassanus) eggs from the Gulf of St. Lawrence, Canada, over a 55-year period (1969-2024). Analyses include 13 perfluoroalkyl carboxylic acids (PFCAs) and four perfluoroalkyl sulfonic acids (PFSAs). Stable isotopes of carbon (δ¹³C) and nitrogen (δ¹⁵N), lipid content, and moisture content were analyzed. Generalized additive models (GAMs), adjusted for lipids and for both lipids and δ¹⁵N, were applied to assess how chemical properties, industrial use, regulatory actions, and trophic dynamics influence PFAS trends. Perfluorooctanesulfonic acid (PFOS) was the dominant compound throughout the study period, peaking in the mid-1990s and declining thereafter due to regulatory measures and voluntary phase-outs. However, PFOS and other PFASs show high persistence, with estimated ecological half-lives for ∑₁₇PFASs of 60 years with lipid correction and 36 years after lipid and δ¹⁵N correction. Some long-chain PFCAs, such as perfluorododecanoic acid (PFDoA; 12 carbons) and perfluorotridecanoic acid (PFTrDA; 13 carbons), have shown a delayed response to regulations. Moreover, PFOS and PFOS + perfluorohexanesulfonic acid (PFHxS) concentrations in northern gannet eggs remained above established toxicological thresholds for 30 years, indicating ecotoxicological risks for marine top predators. These findings highlight the persistent nature of PFAS contamination and underline the importance of regulations, long-term research, and risk assessment.