Spatial profiles of perfluoroalkyl substances and mercury in fish from northern Lake Victoria, East Africa

There is an acute deficit of data on per- and polyfluoroalkyl substances (PFASs) and mercury (Hg) in the open waters of Lake Victoria, East Africa, relative to nearshore areas. We analyzed stable isotopes (delta N-15 and delta C-13), PFASs and Hg in Nile Perch and Nile Tilapia muscle and liver samples from nearshore and open lake locations from the Ugandan part of the lake. The delta N-15 values of Nile Perch muscle indicated a higher trophic level for samples from the open lake than from nearshore locations. Averages of Sigma PFAS concentrations in Nile Perch muscle and liver (0.44 and 1.75 ng/g ww, respectively) were significantly higher than in Nile Tilapia (0.24 and 0.50 ng/g ww, respectively). Sigma PFAS concentrations in muscle of open lake Nile Perch were significantly higher than for nearshore samples. A similar observation was made for total mercury concentrations in muscle (THg_(Muscle)) of Nile Perch. THg was dominated by methyl mercury (MeHg+ , 22-124 ng/g ww) and mercuric mercury (Hg2+ , < MDL-29 ng/g ww) in Nile Perch muscle. Strong correlation between MeHg+ and some PFASs (e.g. PFOS: r = 0.704, P = 0.016) suggested similar exposure routes or factors. Estimated human daily intake values of PFOS from fish consumption were below international limits whereas for MeHg+, the US EPA reference dose was exceeded. (C) 2020 Elsevier Ltd. All rights reserved.