Contamination of water and sediments by obsolete pesticides at Vikuge farm, Kibaha distric, Tanzania

Abstract

Sediments and water from Vikuge State Farm, Coast Region, Tanzania, where, in 1986, a “donation” of 170 m3 of partially expired pesticides were stored in an open shed- which eventually collapsed, were analysed for 80 different pesticide residues and metabolites. DDT and HCH, two of the most persistent organochlorines pesticides, were the most dominant pesticides found in both matrices. In sediments the levels were up to 99,620 mg/kg dry weight of ΣDDT and up to 7,400 mg/kg dry weight of ΣHCH. The mean total HCH concentrations were 0.95 μg/l in tap water, 0.28 μg/l in surface water and 3.09 μg/l in ground water. Of the four common HCH isomers,α-HCH and β-HCH had the highest on average concentrations in the water. Mean total DDT concentrations were 1.76 μg/l in tap water, 0.18 μg/l in surface water and 9 μg/l in ground water. The only other pesticides detected were in sediments and water are azinphos-methyl, an organphosphorous insecticide and thiabendazol, a systemic fungicide, respectively. During the rainy season, the well-water, which is used for domestic purposes by the villagers, has levels of pesticides higher than those allowed by WHO for drinking water. It is thus recommended that immediate decontamination measures be undertaken. In the meantime, villagers should sediment the well-water and should not use not use it at all during the rainy seasons..

Tanzania Journal of Science Vol. 30 (2) 2004: pp. 21-32