Assessment of Organochlorine Pesticides and Polychlorinated Biphenyls in Soils and Sediments from the Upper Athi River


Currently both surface and underground water are becoming increasingly contaminated. Increasing industrial and agricultural activities have greatly increased the levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) especially in soils and sediments which then through run off and percolation contaminate water. The study aimed at protecting human health from adverse effects caused by OCPs and PCBs by specifically determining and comparing concentration of these compounds from the selected sites. OCPs are large class of chlorinated hydrocarbon chemicals such as DDT, dieldrin, chlordane. PCBs on the other hand, are a class of chlorinated organic compounds with biphenyl as the basic structural unit. These two classes of compounds have been reported to generally cause cancer, birth defects and damage to the central nervous system. Studies show that industrial activities and irrigation in the area have a significant impact as far as OCP and PCB pollution is concerned.
Determination of pesticides and PCB residues involved; moisture content determination, sample preparation, extraction, cleaning-up and analysis. Sampling was done in duplicate from the three selected sites i.e. Mombasa road Bridge (downstream), Kitengela Bridge (mid stream) and Athi river upstream.




From all the three sites selected, the concentrations of the detected OCPs were very low as compared to the FAO tolerance limits thus safe in the environment. However, the concentration of PCB-28 was above the FAO tolerance limits for PCBs thus unsafe in the environment. People around therefore, should be notified on the pollution of water to protect their health. Concentration of these compounds from the water itself and fish should also be investigated.


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