Roadkill: An Opportunistic Strategy to Track PFAS in Venomous Snakes in a South African Urban Environment

Per- and polyfluoroalkyl substances (PFAS) are an emerging contaminant globally, with recent attention regarding their presence in South Africa; however, to date, most studies have focused on their presence and impact on aquatic systems. Few sentinels exist capable of defining the presence and role of PFAS in urban environments. Here, we have demonstrated the use of an opportunistic sampling strategy (e.g., roadkill), as a means to obtain specimens capable of defining the potential urban burden of PFAS. Within many urban environments in South Africa, snakes have become widespread, due to the abundance of food and shelter. Employing the roadkill sampling strategy, the livers of three species of apex venomous snakes, black mamba (BM, Dendroaspis polylepis, n = 28), eastern green mamba (Dendroaspis angusticeps, n = 5), and Mozambique spitting cobra (Naja mossambica, n = 6), were sampled. The snakes were then monitored for 30 PFAS in and around the urban center of Durban, South Africa, using liquid chromatography-tandem mass spectrometry. Overall, nine PFAS were quantified across the snakes sampled, dominated by long chain species, along with the presence of an emerging class of replacement PFAS, 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate (6:2 Cl-PFESA). This study reports some of the highest ∑PFAS documented in South African biota at 1084 ng/g dry weight (dw; median ∑PFAS of 511 ng/g dw for BM). While there are obvious caveats to utilizing roadkill for PFAS monitoring, these opportunistic throw-away samples could become useful for tracking the fate of PFAS in threatened or dangerous species, especially within urban environments. Further, these urban sentinels can provide data for a current research gap (terrestrial fate and transport) and offer a glimpse into potential human exposure risks in regions where urban pollution is a growing concern.