Poly- and perfluoroalkylated substances (PFASs) in water, sediment and fish muscle tissue from Lake Tana, Ethiopia and implications for human exposure

• PFCAs were predominant in water (68%), sediment (91%), and fish (71%).
• PFAS levels are higher in piscivorous compared to non-piscivorous fish species.
• PFAS sorption depends on the CF2 moiety and functional group for sediment or biota.
• PFAS levels were generally low and potential risks to humans are not expected.

Lake Tana is Ethiopia's largest lake and there are plans to increase the harvest of fish from the lake. The objective of this study was to assess the levels of poly- and perfluoroalkyl substances (PFASs) in different compartments of the lake (water, sediment, and fish muscle tissue), and its implications for human exposure. The results showed higher PFAS concentrations in piscivorous fish species (Labeobarbus megastoma and Labeobarbus gorguari) than non-piscivorous species (Labeobarbus intermedius, Oreochromis niloticus and Clarias gariepinus) and also spatial distribution similarities. The ∑PFAS concentrations ranged from 0.073 to 5.6 ng L−1 (on average, 2.9 ng L−1) in surface water, 0.22–0.55 ng g−1 dry weight (dw) (on average, 0.30 ng g−1 dw) in surface sediment, and non-detected to 5.8 ng g−1 wet weight (ww) (on average, 1.2 ng g−1 ww) in all fish species. The relative risk (RR) indicates that the consumption of fish contaminated with perfluorooctane sulfonate (PFOS) will likely not cause any harmful effects for the Ethiopian fish eating population. However, mixture toxicity of the sum of PFASs, individual fish consumption patterns and increasing fish consumption are important factors to consider in future risk assessments.

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