Organochlorine Pesticide Residues in Estuarine Fish from the Athi River, Kenya

Abstract

Organochlorine compounds such as DDT, lindane and aldrin are agricultural and public health pesticides that persist in the environment and accumulate in fatty tissues of living organisms. In Kenya, the chemicals were widely used between the mid 1940's and late 1970's in agriculture and aerial control of mosquitoes in the Lake Victoria region. The use of persistent organochlorine pesticides was banned or restricted in Kenya in 1986 (Pest Control Products Board records, 1986; Kimani, 1990- personal communication). Organochlorine pesticides mainly exert their detrimental effects in non-target organisms through chronic toxicity and sub-lethal exposure. This is the main concern for environmental scientists, conservationists and public health workers. DDT and its metabolites cause microsomal enzyme induction (Oestreicher, 1971), egg-shell thinning in birds (Chang and Stockstad, 1975) and tumour induction. DDT also reduces the reproductive success of birds and fish. Aldrin and dieldrin are potentially carcinogenic (lARC, 1974). Lindane and other hexachlorocyclohexane (HCH) isomers produce liver tumours in mice (IARC, 1974). I 'l Studies of organochlorine pesticide residues in _=enyan fish have previously been focused mainly on Lake Victoria (Koeman et al, 1972; Kanja, 1989; Mitema and Gitau, 1990) and the Great Rift Valley lakes (Frank et al, 1977; Lincer et ai, 1981). The present study was done to investigate organochlorine pesticide residue levels in fish from the estuary of Athi River. The main objective of the study was to identify and quantify organochlorine residues in the fish so as to assess the extent of contamination of the river by the pesticides and evaluate the toxicological significance of the findings