LEVELS AND DISTRIBUTION OF POLYCHLORINATED BIPHENYLS (PCBS) IN WATER, SEDIMENT, FISH AND THEIR ASSOCIATED PARASITES IN LAKE VICTORIA - KENYA

Abstract

To fulfill regulatory requirements on flame retardancy, flame retardants like Polychlorinated Biphenyl (PCBs) are incorporated into a number of polymers. These chemicals are toxic, persistent, and bioaccumulate in biota. Yet their concentrations in many aquatic media in Kenya remain ignored. This study investigated the distribution and bioaccumulation of PCBs in water, sediment, fish and bioaccumulation by parasites in Lake Victoria. Water, sediments, fish and the parasites were sampled at six sites in Lake Victoria differing in pollution levels and PCBs analyzed using gas chromatography. The concentration of total indicator PCBs in water samples ranged from 200 pg L-1 to 1980 pg L-1 and displayed significant (P < 0.05) spatial differences linked to anthropogenic pollution. The PCB levels in sediment samples ranged from 350 to 3,800 pg g1, and displayed significant spatial differences (P < 0.05). In the sediments, water and fish, PCB 153 and 180 occurred in high concentration while PCB 28 was the least. The PCB concentrations in fish species ranged from 60 to 140 pg g−1 with site specific variations (P < 0.05); Lates niloticus accumulated highest concentration of PCBs followed by Rastrieneobola argentea while the Oreochromis niloticus had the least concentration of PCBs. Parasite infecting L. niloticus (Protocephalus spp.) and R. argentea (L. intestinalis) accumulated higher concentration of PCBs than parasite infecting O. niloticus (Monobothrium spp.). Ligula intestinalis infesting R. argentea biomagnified PCBs ( 15 times) than the parasites infecting L. niloticus ( 10) while parasites infecting O. niloticus had the least biomagnification of PCBs ( 8-9). These results demonstrate occurrence of PCB in high concentration in water, sediment, and fish. There is need to develop a policy to limit discharge of substances in the environment, there is also a need to develop electronic waste dumping and possible recycling sites. Moreover, there is a need to conduct risk analysis of consuming the fish to ascertain the suitability of fish from the lake for human consumption. The parasites infecting the three commercial fish species should be considered and developed as biomonitor for long term monitoring of PCBs in Lake Victoria as they biomagnify the pollutants over and above that of the fish species. The parasites infecting the three commercial fish species should be considered and developed as biomonitor for localized PCBs levels in Lake Victoria.