Per- and poly-fluoroalkyl substances (PFAS) are a group of contaminants of emerging concern that came into commercial use in the 1940s. They display amphiphilic properties and have become ubiquitous in aquatic environments. PFAS can be toxic to humans and animals. Thus, understanding their prevalence in biota is vital. Data gaps exist regarding wildlife exposure to PFAS, especially for protected species. This work investigates PFAS concentrations in two piscivorous bird species, snowy egrets (Egretta thula) and black-crowned night herons (Nycticorax nycticorax), green turtles (Chelonia mydas), and orca or killer whales (Orcinus orca). In green turtles and orcas, tissue-specific measurements are assessed. A quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was used to extract PFAS from the tissues of these animals, and PFAS concentrations were assessed using liquid chromatography-tandem mass spectrometry. Eggs from the birds were collected during the 2019 and 2020 nesting seasons from nesting sites surrounding Mexico's largest freshwater lake, Lake Chapala. Perfluorooctanoic sulfonic acid (PFOS) was the predominating compound detected, contributing to over 70% of the total PFAS concentrations in both bird species. There was no significant difference in contaminant concentrations between the two species, or between the two nesting seasons, for each compound assessed (two-sided t-test, p < 0.05). In February 2021, along Matagorda Bay, Texas, skin tissue and liver serum were collected from deceased stranded green turtles. PFOS was detected in 85% of the skin samples (n = 14) and 100% of the liver serum samples (n = 26), and total PFAS concentrations were not significantly different between the skin and serum (two-sided t-test, p < 0.05). This highlights the potential to use less-invasive skin sampling to screen for PFAS exposure in the serum of green turtles. In orca, tissue-specific distribution of PFAS was investigated in the liver, blubber, kidney, intestine, and muscle. On a per gram wet weight basis, liver tissue had the highest concentration of PFAS, followed by kidney tissue. PFAS profiles were relatively consistent across the tissues analyzed. This work provides insight into the tissue-specific PFAS accumulation and highlights the exposure to PFAS faced by the endangered Southern Resident Distinct Population Segment.
