Per- and Poly-fluoroalkyl Substances (PFAS) in Circulation in a Canadian Population: Their Association with Serum Liver Enzyme Biomarkers and Piloting a Novel Method to Reduce Serum PFAS

Extensive use of per- and polyfluoroalkyl substances (PFAS) has resulted in their ubiquitous presence in human blood. PFAS exposures have been associated with multiple adverse human health effects including increased risk of liver damage, elevated serum lipids, impaired vaccine response, adverse birth outcomes and cancer. Biomonitoring studies have focused on measuring long-chain PFAS, but these are being replaced by shorter chain PFAS and PFAS with alternative structures, resulting in incomplete understanding of human exposures. Here, we take advantage of serum samples collected as part of a clinical trial testing the efficacy of a dietary fiber intervention to reduce serum cholesterol to investigate exposure to legacy and replacement PFAS chemicals in Canadian participants. Serum samples were collected from 72 participants in 2019-2020 at baseline and after 4 weeks of the intervention and were analyzed for 17 PFAS species. The highest geometric mean concentrations of PFAS measured at baseline corresponded to PFOSA (7.1 ng/ml), PFOS (4.2, ng/ml), PFOA (1.8 ng/ml) and PFHxS (1.3 ng/ml). Short chain PFAS including PFBuA, PFHxS and/or PFHpA were detected in 100% of participants and GenX was detected in 70% of participants. Analyses of associations between PFAS serum concentrations and biomarkers of adverse health outcomes showed the PFBuA, PFHxA, PFDA and PFOSA were associated with higher serum gamma-glutamyl transferase concentrations but not with measures of serum total or low-density lipoprotein cholesterol. Comparison of PFAS concentrations at baseline and after a 4-week follow-up showed that total PFAS concentrations decreased in both the control and cholesterol intervention groups. However, the suite of PFAS of concern identified by the United States National Academies of Sciences, Engineering, and Medicine, significantly decreased only in the cholesterol intervention group. This observation suggests that a dietary fiber intervention may reduce PFAS body burden, but future intervention studies need to control for PFAS exposure sources and extend beyond 4 weeks. Overall, the results show that exposures to short-chain and alternative PFAS are common in this Canadian population.