Domestic Dogs and Horses as Sentinels of Per- and Polyfluoroalkyl Substance Exposure and Associated Health Biomarkers in Gray's Creek North Carolina

Abstract

Central North Carolina (NC) is highly contaminated with per- and polyfluoroalkyl substances (PFAS), in part due to local fluorochemical production. Little is known about the exposure profiles and long-term health impacts for humans and animals that live in nearby communities. In this study, serum PFAS concentrations were determined using liquid chromatography high-resolution mass spectrometry and diagnostic clinical chemistry endpoints were assessed for 31 dogs and 32 horses that reside in Gray's Creek NC at households with documented PFAS contamination in their drinking water. PFAS were detected in every sample, with 12 of the 20 PFAS detected in ≥50% of samples from each species. The average total PFAS concentrations in horses were lower compared to dogs who had higher concentrations of PFOS (dogs 2.9 ng/mL; horses 1.8 ng/mL), PFHxS (dogs 1.43 ng/mL, horses < LOD), and PFOA (dogs 0.37 ng/mL; horses 0.10 ng/mL). Regression analysis highlighted alkaline phosphatase, glucose, and globulin proteins in dogs and gamma glutamyl transferase in horses as potential biomarkers associated with PFAS exposure. Overall, the results of this study support the utility of companion animal and livestock species as sentinels of PFAS exposure differences inside and outside of the home. As in humans, renal and hepatic health in domestic animals may be sensitive to long-term PFAS exposures.

Keywords: GenX chemicals; One Health; PFOA; PFOS; canine; drinking water; equine; fluoroether; nafion by-product 2.

Figure 1.

Comparison of PFAS in dogs and horses. Results of (A) unsupervised hierarchical clustering and (B) principal component analysis of Log₁₀(X + 1) transformed serum PFAS concentrations from dogs and horses. (C) Differences between mean Log₁₀(X + 1) transformed serum PFAS concentrations with 95% confidence intervals, dog–horse (fluoroethers, green; sulfonics, purple; carboxylics, orange; **p ≤ 0.01; ****p ≤ 0.0001); dog n = 31 and horse n = 32.

Figure 2.

Comparison of PFAS in dogs’ drinking well or bottled water. Results of (A) unsupervised hierarchical clustering and (B) principal component analysis of Log₁₀(X + 1) transformed serum PFAS concentrations from dogs given bottled water and well water. (C) Difference between mean Log₁₀(X + 1) transformed serum PFAS concentrations with 95% confidence intervals, well–bottled (fluoroethers, green; sulfonics, purple; carboxylics, orange; ****p ≤ 0.0001). Dogs given well water (n = 14) compared to bottled water (n = 17).