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In Tanzania fish is one of the most important protein sources for the rapidly increasing population. Wild fish is
threatened by overfishing and pollution from agriculture, industries, mining, household effluents and vector
control. Tomonitor possible implications for public health, the geographical differences of the occurrence and levels
of persistent organic pollutants (POPs) in tilapia fish (Oreochromis sp.) from four different Tanzanian lakes were investigated
in 2011. Concentrations of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs),
polybrominated diphenyls (PBDEs) and hexabromocyclododecane (HBCDD) were determined in pooled samples
of tilapia muscle from Lake (L) Victoria, L. Tanganyika, L. Nyasa (also called L. Malawi) and L. Babati in Tanzania in
2011. Levels of Σ-DDTs (274 ng/g lipid weight (lw)) and sum of 7 indicator PCBs (Σ-7PCBs) (17 ng/g lw) were
significantly higher in tilapia from L. Tanganyika compared to the other lakes. The highest levels of Σ-endosulfan
(94 ng/g lw) were detected in tilapia from L. Victoria. Toxaphenes were detected in low levels in fish from L.
Tanganyika and L. Babati. Results revealed a geographic difference in the use of DDT and endosulfan between L.
Victoria and L. Tanganyika. Low ratios of DDE/DDT in tilapia from L. Tanganyika indicated an on-going use of
DDT in the area. Median levels of ΣBDEs, including BDE-209, were highest in L. Victoria (19.4 ng/g lw) and BDE-
209 was present in 68% of the samples from this lake. The presence of BDE-209 indicates increasing influence of imported products from heavy industrialized countries. The measured POP levels in the studied tilapia were all
below MRLs of EU or were lower than recommended levels, and thus the fish is considered as safe for human
consumption. They may, however, pose a risk to the fish species and threaten biodiversity. |
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