DDT And Endosulfan Residues In Fish From Hola Irrigation Scheme, Tana River Kenya

Abstract

The levels of concentration of residues of the organochlorine pesticides DDT and its principal metabolites DDE and DDD, and endosulfan and its metabolite endosulfan sulphate were investigated in fish from the Hola irrigation scheme, in the Lower Tana river basin, where the pesticides were used for the control of cotton and maize pests. Endosulfan was applied on cotton by aerial spraying, whereas DDT was applied on cotton by aerial spraying, or dusted on maize. Four fish species were studied for residues of the organochlorine pesticides, namely, Clarias mossambicus (Peters), Labeo gregorii (Boulenger), Oreochromis mossambicus (Trewavas), and Tilapia zilli (Gervais), caught from sampling sites within the irrigation scheme, and the Tana river itself. The concentrations of residues found in fish tissues •.are discussed with reference to the influence of several factors, namely, the body mass, fat content", location of the sampling site wi thin and without "',the irrigation scheme, the fish species, .arid type of-tissue or organ.