We investigated the presence of metals (Zn, Cu, Cd, Pb, and Hg) and per- and polyfluoroalkyl substances (PFAS) in eastern oysters (Crassostrea virginica) from the White Oak River Basin (WORB), a sparsely populated coastal watershed in North Carolina, USA. We compared wild and farmed oysters to evaluate whether their positions within the water column influenced contaminant accumulation. Consumption risk was also assessed based on meal size, toxicological guidance values, and individual physiological parameters. Metals and PFAS were consistently detected in oysters across the WORB but generally occurred at low concentrations. Spatial patterns suggest that metal concentrations may be largely influenced by geogenic or background sources, whereas PFAS contamination may originate primarily from nonpoint sources. Despite low contaminant concentrations, estimated consumption risk varied among analytes, with substantial uncertainty associated with current toxicological and regulatory guidance. These findings improve understanding of contaminant fate and bioaccumulation in a coastal system with limited anthropogenic land use and provide a framework for evaluating bivalve consumption risk that incorporates contaminant-specific toxicity and individual physiological characteristics.
Caroline Z. Rudd, Marzieh Shojaei, Nelson A. Rivera et al.· ACS ES&T water· 0 citations
Per- and polyfluoroalkyl substances (PFAS) have been increasingly reported in pesticide formulations, raising concerns regarding their contribution to agricultural PFAS contamination. However, uncertainties remain regarding PFAS composition, unidentified PFAS, and the environmental relevance of PFAS in currently used pesticides. This study characterizes PFAS in six commercial pesticides using target and nontarget analysis, evaluates sample preparation methods, and assesses environmental implications of pesticide applications. Solvent dilution and EPA 1633 were selected based on favorable internal standard and matrix spike (MS) recoveries. The total oxidizable precursors (TOP) assay was applied to all formulations. No PFAS were detected before and after TOP in two formulations. Four PFAS were detected in the remaining formulations at concentrations of 40 ng/L-pesticides (6:2 FTS, malathion)─39,123 ng/L-pesticides (6:2 FTS; spiromesifen). Increased perfluoroalkyl carboxylates after TOP suggested unknown PFAS in spiromesifen, imidacloprid, and malathion. Nontarget analysis tentatively identified two additional PFAS (CAS Nos. 376-27-2 and 2681-00-7) in imidacloprid. Total organic fluorine (TOF) analysis achieved 84% MS recovery; but sample concentrations were below detection by a combustion ion chromatography (CIC), suggesting larger sample volumes are needed. Simulated results based on PFAS concentration fluxes indicated currently used pesticides are unlikely to be a major source of groundwater or soil contamination.
Zhao Yang, Alonso Doria Manzur, Marzieh Shojaei et al.· ACS ES&T Water· 0 citations
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