Preliminary study on the distribution of metals and persistent organic pollutants (POPs), including perfluoroalkylated acids (PFAS), in the aquatic environment near Morogoro, Tanzania, and the potential health risks for humans

Abstract

Metals and persistent organic pollutants (POPs), including perfluoroalkylated acids (PFAS), are chemicals with a bioaccumulative potential that are detected in wildlife around the world. Although multiple studies reported the pollution of the aquatic environment with these chemicals, only limited data is present on the environmental pollution of Tanzania's aquatic environment and the possible risks for human health through consumption of contaminated fish or invertebrates. In the present study, we examined the distribution of metals and POPs in fish, invertebrates, sediment and water, collected at two different years at multiple important water reservoirs for domestic and industrial purposes, in the aquatic environment near Morogoro, Tanzania. Furthermore, we assessed the possible risks for human health through consumption of contaminated fish and shrimp.Metal concentrations in the water, sediment, invertebrates and fish appeared to increase in sites downstream from Morogoro city, likely caused by the presence of the city as pollution source. Significant differences in accumulated concentrations of metals and POPs were observed between species, which was hypothesized to be caused by dietary differences. Concentrations of multiple metals exceeded water and sediment quality guidelines values. Only Cu (2.8–17 μg/L) and Zn (<LOQ – 151 μg/L) in water exceeded chronic and acute effect values. Furthermore, PFOS, PBDE and HCB concentrations exceeded biota quality standard values, suggesting an ecological risk caused by these metals and POPs in the aquatic environment around Morogoro.Our results suggest that potential health effects through consumption of contaminated shrimp, and to minor extent fish, are expected. The daily consumption of these proteins (0.016–0.027 kg/capita/day) in Tanzania is similar or higher than the tolerable maximum consumption of shrimp for Cu (<0.02 kg/capita/day), Co (<0.02 kg/capita/day) and PFOS (<0.01 kg/capita/day). The outcome of this study could be used in future studies on metals and POPs in African aquatic ecosystems.