Presence of per- and poly-fluoroalkyl substances (PFAS) in brain samples of marine mammals from the St. Lawrence Estuary and Gulf, Canada

Abstract

This study focused on measuring 80 target per- and poly-fluoroalkyl substances (PFAS) in brain samples from various marine mammals, including: harbor seal, gray seal, harp seal, hooded seal, harbor porpoise, white-sided dolphin, white-beaked dolphin, and True’s beaked whale, all collected from the St. Lawrence Estuary and Gulf. A total of 34 PFAS compounds were detected in these mammals. The geometric mean of the detected PFAS levels ranged from 0.02 ng/g wet weight (ww) to 41 ng/g ww. Notably, the detection frequency for PFOS was very high at 97.5%. For individual long-chain C9 to C13 perfluorocarboxylic acids (PFCAs), the detection frequencies ranged from 77% to 95%. In contrast, the detection frequencies for C3 to C6 PFCAs specifically PFHxA, PFBA, and PFPrA were much lower, ranging from 2.5% to 5%. This indicates a greater tendency for long-chain PFCAs to accumulate compared to shorter-chain variants. Additionally, a higher occurrence of PFSAs and PFCAs was observed across all species examined. Interesting findings emerged regarding species at higher trophic levels, such as the white-sided dolphin, white-beaked dolphin, and True’s beaked whale, which exhibited significant levels of fluorinated alkyl substance acids (FASAs) and their alternatives (FASAAs). In a comparative analysis of PFAS distribution in liver, muscle, and brain tissues, correlation analysis revealed that these tissues are positively correlated with each other. This study highlights concerns regarding the impact of PFAS on marine aquatic systems and potential neurocognitive impacts on their brain functions.