Organophosphate and organochlorine exposure in selected horticultural farms in Zimbabwe

Abstract

The epidemiology of pesticide use and pesticide exposure in the farming communities has been researched on and documented. The results from these studies, conducted in all sectors of agriculture except horticulture show high levels of occupational exposure. We present a pilot study conducted in two horticultural farms in Ruwa and Domboshawa 25 kilometres and 30 kilometres from Harare respectively in 2001.The main objective was to establish the level and prevalence of pesticide exposure in workers in the horticultural industry. Blood samples were collected from 33 workers from the two farms. Cholinesterase activity was measured using the WHO cholinesterase kit and organochlorine residues were analysed using the GC method. Organochlorine residues were detected in the following order of frequency, pp-DDT, 100%; op-DDT, 100%; aldrin, 95%; a-HCH, 100%; dieldrin, 86.4%; heptachlor, 22.7% and opDDD, 18.2% from the blood samples analysed. The ppDDT isomer was the major contributing isomer to the sumDDT. The two isomers a- and ß-HCH were also detected in the samples analysed and the former being the major contributing isomer to the sum-HCH. In Ruwa the exposed subjects had higher DDT blood levels than the control group though this was not statistically significant (p=0.1855). There was also no significant difference in the mean DDE levels of the exposed group and the control group (p=0.6851). Significant differences were however noted in the mean blood levels of a-HCH (p=0.007) and aldrin (p=0.0187). In Domboshawa there were no significant differences in the mean blood levels of organochloride residues between the exposed and the control. No significant depression of the cholinesterase activity was observed. The results demonstrated a high level of pollution of human blood with organochlorine residues. The pollution was due to both occupational and environmental exposure.

Keywords: Organochlorine, pesticide exposure, horticulture