Bioaccumulation and Tissue Partitioning of Endosulfan by the Red Hybrid Tilapia

The frequent use of endosulfan in agricultural activity on steep slopes in Jamaica and subsequent contamination of rivers by the residues resulted in a need to assess the levels of bioaccumulation of sub-lethal doses of the insecticide in river fauna using Tilapia fish as a test subject. Bioconcentration of α- and β-endosulfan by the Red Hybrid Tilapia, from 0.0075 mg L^-1 in the surrounding water, reached a peak (0.578 ppb and 0.442 ppb, respectively) in one to four hours but fluctuated during the rest of the 72-h observation period. A similar pattern of bioaccumulation was recorded when the fish were exposed to 0.015 mg L^-1, except that the peak bioaccumulation of α- and β-isomers after one hour of exposure were 0.54 and 0.44 mg L^-1, respectively. The contaminated fish (from 24-h exposure to 0.015 mg L^-1) eliminated only 18 to 31% of endosulfan residues after 24 h and 26 to 39% after 72-h exposure to uncontaminated water. During the process of bioconcentration, endosulfan was metabolized to endosulfan lactone and sulfate; the degradation was more during the elimination process when exposed to clean water. Maximum amounts of α-and β-endosulfan and their metabolites were partitioned in gonads > liver > gills > skin/muscle/bone.