Per- and polyfluoroalkyl substances (PFASs) in blood of captive Siberian tigers in China: Occurrence and associations with biochemical parameters

Per- and polyfluoroalkyl substances (PFASs) have been ubiquitously detected in the environment and marine animals. However, little is known about these substances and their associations with health parameters in wild terrestrial mammals. In this study, we determined PFAS levels and distribution in the blood of captive Siberian tigers in Harbin, China, and evaluated potential exposure pathways by daily intake. In addition, for the first time, we explored the associations between serum PFAS concentrations and clinical parameters. Results showed that perfluorooctanoate (PFOA) was the dominant PFAS compound in blood (accounting for 64%), followed by perfluorooctanesulfonate (PFOS). In addition, 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) concentrations were also detected in blood and dietary food. Furthermore, significant positive age relationships were observed for levels of perfluoroheptanoate (PFHpA), PFOA, PFOS, and 6:2 Cl-PFESA in the blood of female tigers. Results showed that PFOA and PFOS in dietary food accounted for over 70% of total daily intake of PFASs, indicating that meat consumption is a predominant exposure pathway in tigers. We also found positive associations between higher exposure to PFASs (including PFOA, PFOS, and 6:2 Cl-PFESA) and elevated serum levels of alanine transaminase (ALT), a marker of liver damage. Thus, comprehensive health assessments of PFAS burdens in wildlife are needed.