Perfluorinated compounds in the aquatic food chains of two subtropical estuaries

Per- and polyfluoroalkyl substances (PFASs) are ubiquitous in the environment and remain in largely unknown concentrations and with unknown effects on the African continent. Here we aimed to assess the presence of 15 PFASs in different compartments of the aMatikulu and uMvoti estuaries and to examine potential risks for human health through the consumption of contaminated fish. This is the first known study to assess PFASs in South African estuaries. Thirteen out of the fifteen PFASs were detected in water, sediment and biota samples from both estuaries, with perfluorooctanoic acid (PFOA), detected in every sample. PFOA concentrations from uMvoti water samples were the highest recorded to date in South African waters. PFOA was found in high concentrations in all water samples with an average range between 171 and 258 ng/L in the aMatikulu and 711-788 ng/L in the uMvoti. Perfluorooctane sulfonate (PFOS) concentrations in fish tissue samples were significantly higher than other PFASs. PFOS concentrations in all fish species caught in the aMatikulu ranged between 0.09 and 2.25 ng/g wet weight (ww) in muscle tissue and 1.5-12.08 ng/g ww in liver tissue, while PFOA concentrations ranged between 0.08 and 0.67 ng/g ww in muscle tissue and 0.54-1.48 ng/g ww in liver tissue. Concentrations of PFASs were only measured in Oreochromis mossambicus from the uMvoti and contained PFOS concentrations ranging from 0.18 to 0.97 ng/g ww in muscle tissue and 7.29-27.96 ng/g ww in liver tissue. PFOA concentrations ranged between 0.12 and 0.58 ng/g ww in muscle tissue and 0.17-1.01 ng/g ww in liver tissue. PFAS concentrations in all fish sampled were below the calculated Minimum Risk Levels (MRLs) for safe human consumption.