Acute ill-health amongst farmers using pesticides to treat sheep against ectoparasites

  • Hanaa Bayomy

    Student thesis: Phd


    In the last two decades attention has been directed towards flu-like symptoms ("dipper's flu"; DF) in sheep farmers following the treatment of sheep against ectoparasites using organophosphate (OP) based dips. However the nature and cause of DF remain unclear. The overall aims of this project were to identify the clinical pattern of acute ill-health arising after sheep treatment and to evaluate whether this ill-health may be caused by pesticide exposure through statistical analysis of the data collected by the UK Health and Sheep Dipping Survey. This prospective study collected detailed information on (i) health and exposures, (ii) urine samples pre- and post-treatment, and (iii) symptoms reported in a diary during the week following treatment These analyses included: (i) identifying the determinants of exposure to pesticides (OPs and synthetic pyrethroids) by measurement of urinary metabolites before and after treatment, (ii) management of missing data in Health Questionnaires (HQs) completed before and after treatment using a multiple imputation approach, (iii) assessing the association between pesticide exposure and DF using previously published definitions of DF derived from the HQs using least square regression, (iv) identifying patterns of self-reported acute symptoms using Exploratory Factor Analysis (EFA) of HQ responses, (v) determining the association between pesticide exposure and any newly identified symptom patterns and (vi) assessing of the risk of daily ill-health in relation to pesticide exposure using biologically distributed lag models.Sheep treatment was associated with increased exposure to OPs (diazinon), but not pyrethroids as levels of total diazinon urinary metabolites were higher post-treatment (P=0.01). Increased urinary levels of diazinon metabolites were associated with product splashing (P=0.02), the number of sheep treated (P=0.005) and the number of hours treating (P
    Date of Award1 Aug 2012
    Original languageEnglish
    Awarding Institution
    • The University of Manchester
    SupervisorAndrew Povey (Supervisor) & Frank De Vocht (Supervisor)

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