Soil and water contamination with carbofuran residues in agricultural farmlands in Kenya following the application of the technical formulation Furadan.

This study was undertaken to determine the concentrations of carbofuran residues in water, soil and plant samples from selected sites in the farmlands in Kenya and to demonstrate the impact of Furadan use on the local environment. Soil, water and plant samples obtained from agricultural farmlands where the technical formulation Furadan has been used extensively showed high environmental contamination with concentrations of carbofuran and its two toxic metabolites 3-hydroxycarbofuran and 3-ketocarbofuran, separately, ranging from 0.010-1.009 mg/kg of dry surface soil, 0.005-0.495 mg/L in water samples from two rivers flowing through the farms and bdl-2.301 mg/L in water samples from ponds and dams located close to the farms. Maize plant samples contained these residues in concentrations ranging from 0.04-1.328 mg/kg of dry plant tissue. The significantly high concentration levels of carbofuran and its metabolites, 3-ketocarbofuran and 3-hydroxycarbofuran, found in various matrices demonstrate that Furadan was used extensively in the two areas and that there was environmental distribution and exposure of residues in water which posed risks when used for domestic purposes or as drinking water for animals in two wildlife conservancies where the dams and ponds are located. Surface soil contamination was also high and posed risks through run-off into the dams and rivers as well as through secondary exposure to small birds and mammals.

Carbofuran and its toxic metabolites provide forensic evidence for furadan exposure in vultures (Gyps africanus) in Kenya.

Forensic analysis of carbofuran residues in weathered tissue samples for evidence of Furadan exposure in vultures (Gps africanus) by HPLC gave concentration (mg/Kg dry tissue weight) ranges of bdl - 0.07 (carbofuran), bdl - 0.499 (3-ketocarbofuran) and 0.013-0.147 (3-hydroxycarbofuran) in beaks, bdl-0.65 (carbofuran), 0.024-0.190 (3-ketocarbofuran) and 0.017-0.098 (3-hydroxycarbofuran) in feet, 0.179-0.219 (3-ketocarbofuran) and 0.081-0.093 (3-hydroxycarbofuran) in crop content, 0.078-0.082 (3-ketocarbofuran) and 0.091-0.101 (3-hydroxycarbofuran) in muscle of a laced carcass and 0.006-0.014 (carbofuran), 0.590-1.010 (3-ketocarbofuran) and 0.095-0.135 (3-hydroxycarbofuran) in soil sampled from a poisoning site. These compounds were confirmed by GC-MS. The results showed that HPLC combined with GC-MS is suitable for forensic analysis of carbofuran residues in bird tissue samples and that forensic investigation should include its two toxic metabolites, 3-hydroxycarbofuran and 3-ketocarbofuran.