The health hazards of chemical use in agriculture

Master Thesis


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University of Cape Town

Despite playing an important role in crop protection and increasing food production, chemicals used in agriculture may have a range of unanticipated effects on human health. Such effects may range from overt and acute poisonings to gradual-onset chronic morbidity. In South Africa, data on such morbidity are sparse, and subject to much underreporting as one of the included papers illustrates. The dearth of such data has much to do with the marginalised living and working conditions in agriculture and the lack of attention to occupational and environmental health on farms in the country. We have little sense of the extent of hazardous exposures in agriculture, nor of their health impacts on rural populations. Even less so, have methods for the control of poisoning by pesticides been investigated amongst farm workers in South Africa. A public health response to this problem should aim at all levels of prevention (primary, secondary and tertiary), by characterising the extent and distribution of the problems caused by pesticides, identifying risk factors and groups at highest risk for poisoning, as well as testing intervention strategies and technologies. The set of papers presented below attempts to do that by linking a series of investigations into different aspects of agrichemical hazards in South Africa, with a focus on the Western Cape. The first paper examined various aspects of potential exposure to agrichemicals on farms in the Stellenbosch region, taking into account both environmental and occupational routes of exposure. The second paper describes the profile of agrichemical poisoning in the province from 1987 to 1991, identifying high risk groups and characterising the completeness and nature of reported poisonings. The third paper developed from the author's growing realisation of the need to contextualise problems related to agrichemical exposures and effects within the overall legislative and public health framework in South Africa. This paper therefore identifies the key public health issues that need addressing with regard to pesticide safety. Finally, the last two papers address aspects related to workplace interventions for the prevention of agrichemical poisoning. One paper deals with the evaluation of a field kit (for validity and repeatability) for monitoring workers exposed to organophosphate and carbamate insecticides, while the last paper elaborates guidelines for the use of cholinesterase testing in the primary and secondary prevention of organophosphate and carbamate poisoning. In this series, therefore, the papers attempt to address the problem of agrichemical hazards within a public health framework, tracing the problem from potential exposure to acute outcomes, through reviewing the legislative and occupational health environments, through to technologies and policy guidelines related to workplace intervention. In doing so, the papers use the term "agrichemical" to refer to all chemicals used in agriculture for pest and weed control. This supersedes the term "pesticide" which has ambiguous meanings in the technical environment. Readers are therefore advised to understand the term "agrichemical" to include the generic aspects of chemical usage on crops in agriculture. The research on which these papers was based was spawned by the involvement of the author in a larger research project investigating long-term neurobehavioural effects of organophosphate exposure on deciduous fruit farm workers over the period 1991 - 1994. This latter piece of research is not referred to here as it was the basis for another degree at the University of Cape Town.

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  • Agrichemical safety practices on farms in the Western Cape. London L. SA Med J 1994 ; 84 : 273-278. * Notification of pesticide poisoning in the Western Cape 1987 - 1991. London L, Ehrlich R, Rafudien S, Krige F, Vurgarellis P. SA Med J 1994 ; 84 : 269-272. * Critical Issues in agrichemical safety in South Africa. London L, Myers JE. Am J Ind Med 1995 ; 27(1) : 1-14. * Repeatability and validity of a field kit for estimation of cholinesterase in whole blood. London L, Thomson ML, Sacks S, Fuller B, Bachmann OM, Myers JE. Occupational and Environmental Medicine 1995; 52 : 57-64. * Biological Monitoring of workers exposed to organophosphate pesticides: Guidelines for field application. London L. Occupational Health Southern Africa July/August 1995 ; 1(4) : 13-17.