PFASs in Galveston Bay and the Gulf Of Mexico: Water, Biota, and Developing an Exposure Biomarker

Abstract

Per and polyfluoroalkyl substances (PFASs) are a group of emerging pollutants that have been of increasing regulatory concern due to their persistence in the environment, toxicity, and potential to accumulate in biota. While attention to PFASs has grown in recent years, there is limited knowledge of their fate and distribution in estuarine/coastal biota in the environment. This dissertation quantified up to twelve EPA priority PFASs in surface waters, shellfish and fish after PFAS containing aqueous film forming foams (AFFFs) extinguished a petrochemical fire (Deer Park, TX). Perfluorooctane sulfonate (PFOS) levels in surface water, eastern oyster, and spotted seatrout were all higher immediately following the fire, and then decreased with time. A risk assessment of seafood safety for human consumption indicated no restrictions for oyster consumption, but a 1–2 meal/week limit for the consumption of gafftopsail catfish and red drum from Galveston Bay. An integrated in silico systems toxicological framework was then utilized to identify physiologically relevant biomarkers of PFOS toxicity. Flux balance analysis (FBA) was used to analyze existing toxicological transcriptomics and metabolomics datasets in which embryo-larval life stages of zebrafish were exposed to PFOS. Carnitine (essential for mitochondrial fatty acid β-oxidation) was identified as a diagnostic metabolite biomarker of PFOS exposure along with fatty acids. The putative toxicity biomarkers of PFOS were subsequently assessed in liver from fish from Galveston Bay and the northwestern Gulf of Mexico (fish and dolphin). The multivariate analysis of PFOS liver body-burdens and biomarkers showed carnitine (total and free) as a more modal biomarker of PFOS exposure in aquatic organisms than fatty acids (i.e., significantly, and positively correlating with PFOS body-burdens). Overall, this dissertation expands upon the knowledge of PFAS compounds in aquatic systems by being the first to report levels for Galveston Bay biota, highlight the efficacy of FBA as an approach for physiologically relevant biomarker discovery, and suggest the use of a metabolic cofactor (carnitine) as a generic biomarker of PFOS exposure. These results contribute to the environmental monitoring and hazard assessment efforts of PFOS and its impacts in ecosystems.