Contamination Of Zimbabwean Seed Cotton With Endosulfan Pesticide Residues

摘要

Cotton production in Zimbabwe involves intensive use of synthetic chemicals such as endosulfan for the control of bollworms. The presence of endosulfan residues in seed cotton poses a threat to the health of humans who come in contact with fibres or cotton dust containing this chemical if it exceeds the recommended residue limits. This study set forth to determine the levels of endosulfan in seed cotton produced in four major cotton production areas in Zimbabwe. Soxhlet extraction was used for isolation of endosulfan from seed cotton samples and further sample clean-up was done using solid phase extraction (SPE). The analytical procedure was done using a gas chromatograph equipped with an electron capture detector (GC/ECD). The results showed that maximum concentrations of endosulfan in Gokwe North, Gokwe South, Sanyati and Chinhoyi were 3.11ppm, 0.85ppm, 1.2ppm and 0.1ppm respectively. The recommended limit for endosulfan in cotton fibres is 0.5ppm. Pesticide concentrations which exceeded the maximum recommended limits of 0.5ppm were linked to the pesticide application practices namely application rate, frequency of spraying, pre-harvest interval and the method of application.