Neurobehavioural effects of pesticide exposure among emerging farmers in the Western Cape

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dc.contributor.advisorLondon, Leslieen_ZA
dc.contributor.advisorDalvie, Mohamed Aqielen_ZA
dc.contributor.authorHoltman, Zeldaen_ZA
dc.date.accessioned2014-10-21T13:54:43Z
dc.date.available2014-10-21T13:54:43Z
dc.date.issued2013en_ZA
dc.descriptionIncludes bibliographical references.en_ZA
dc.description.abstractThe number of emerging farmers is increasing in South Africa. This study investigated neurotoxic effects resulting from long-term low-level exposure to organophosphate pesticides amongst emerging farmers. A cohort study involving 319 (66% male and 34% female) emerging farmers in the Western Cape was conducted between 2009 and 2010. Testing included a questionnaire exploring demographic details, work history, medical history; the Q16 and the Brief Symptom Inventory (BSI). Additionally, neurobehavioural performance was assessed on the following: Digit span forward and backward, Digit Symbol, Santa Ana Pegboard, Pursuit Aiming, Benton Visual Retention and Vibration sense as measured by vibration sense threshold using a 256 Hz frequency tuning fork. Exposure to OP's was derived from three metrics: (i) OP applicator status, (ii) cumulative OP exposure weighted for task/activity, (iii) diagnosed past poisoning. Two sets of analyses were conducted: a cross-sectional analysis at baseline (N=319), and a cohort analysis (N=273), comparing change in neurobehavioural performance over the 12 month follow up period. The exposure variable for cumulative occupational OP exposure in the baseline cross-section was generated from the job history data in the farmer questionnaire based on the exposure obtained during the current job and preceding three jobs. This represented long-term past OP exposure. In both the baseline cross-section and the cohort analysis, the relationship investigated was between dichotomised outcomes and four models for OP exposure. Three models used each of the metrics for OP exposure and a fourth model used the metric of cumulative OP exposure adjusted for diagnosed past poisoning. The difference between the analysis in the cohort was that both cumulative exposure and acute poisoning were restricted to the 12 months of follow up, whereas the baseline, both cumulative and acute poisoning were based on any past exposure without a time period. Further, for the cohort study (n=273), the outcomes were the difference in scores (measured as the ratio of the repeat measure at one year to the baseline score) which were regressed in the four exposure models outlined above. All models were controlled for confounders including age, gender, schooling, language, current alcohol consumption, previous head injuries, psychological illness and socioeconomic status. Model building led to the inclusion of additional co-variates for some of the analyses.en_ZA
dc.identifier.apacitationHoltman, Z. (2013). <i>Neurobehavioural effects of pesticide exposure among emerging farmers in the Western Cape</i>. (Thesis). University of Cape Town ,Faculty of Health Sciences ,Department of Public Health and Family Medicine. Retrieved from http://hdl.handle.net/11427/8715en_ZA
dc.identifier.chicagocitationHoltman, Zelda. <i>"Neurobehavioural effects of pesticide exposure among emerging farmers in the Western Cape."</i> Thesis., University of Cape Town ,Faculty of Health Sciences ,Department of Public Health and Family Medicine, 2013. http://hdl.handle.net/11427/8715en_ZA
dc.identifier.citationHoltman, Z. 2013. Neurobehavioural effects of pesticide exposure among emerging farmers in the Western Cape. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Holtman, Zelda AB - The number of emerging farmers is increasing in South Africa. This study investigated neurotoxic effects resulting from long-term low-level exposure to organophosphate pesticides amongst emerging farmers. A cohort study involving 319 (66% male and 34% female) emerging farmers in the Western Cape was conducted between 2009 and 2010. Testing included a questionnaire exploring demographic details, work history, medical history; the Q16 and the Brief Symptom Inventory (BSI). Additionally, neurobehavioural performance was assessed on the following: Digit span forward and backward, Digit Symbol, Santa Ana Pegboard, Pursuit Aiming, Benton Visual Retention and Vibration sense as measured by vibration sense threshold using a 256 Hz frequency tuning fork. Exposure to OP's was derived from three metrics: (i) OP applicator status, (ii) cumulative OP exposure weighted for task/activity, (iii) diagnosed past poisoning. Two sets of analyses were conducted: a cross-sectional analysis at baseline (N=319), and a cohort analysis (N=273), comparing change in neurobehavioural performance over the 12 month follow up period. The exposure variable for cumulative occupational OP exposure in the baseline cross-section was generated from the job history data in the farmer questionnaire based on the exposure obtained during the current job and preceding three jobs. This represented long-term past OP exposure. In both the baseline cross-section and the cohort analysis, the relationship investigated was between dichotomised outcomes and four models for OP exposure. Three models used each of the metrics for OP exposure and a fourth model used the metric of cumulative OP exposure adjusted for diagnosed past poisoning. The difference between the analysis in the cohort was that both cumulative exposure and acute poisoning were restricted to the 12 months of follow up, whereas the baseline, both cumulative and acute poisoning were based on any past exposure without a time period. Further, for the cohort study (n=273), the outcomes were the difference in scores (measured as the ratio of the repeat measure at one year to the baseline score) which were regressed in the four exposure models outlined above. All models were controlled for confounders including age, gender, schooling, language, current alcohol consumption, previous head injuries, psychological illness and socioeconomic status. Model building led to the inclusion of additional co-variates for some of the analyses. DA - 2013 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2013 T1 - Neurobehavioural effects of pesticide exposure among emerging farmers in the Western Cape TI - Neurobehavioural effects of pesticide exposure among emerging farmers in the Western Cape UR - http://hdl.handle.net/11427/8715 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/8715
dc.identifier.vancouvercitationHoltman Z. Neurobehavioural effects of pesticide exposure among emerging farmers in the Western Cape. [Thesis]. University of Cape Town ,Faculty of Health Sciences ,Department of Public Health and Family Medicine, 2013 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/8715en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Public Health and Family Medicineen_ZA
dc.publisher.facultyFaculty of Health Sciencesen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.titleNeurobehavioural effects of pesticide exposure among emerging farmers in the Western Capeen_ZA
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationnamePhDen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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