title: Pesticide exposure and screen-positive neuropsychiatric disease in British sheep farmers.
abstract: BACKGROUND
  Epidemiological evidence linking low dose pesticide exposure and chronic ill-health in UK sheep farmers is limited. Our aim was to examine whether neuropsychiatric disorders were associated with low dose chronic and/or more acute pesticide exposure in sheep farmers.
  
  
  METHODS
  A cohort of British farmers working in the 1970s was sent a screening questionnaire which asked about their health and work history. The prevalence of screen-positive depression, dementia, Parkinsonism and neuropathy was determined using a priori algorithms. Self-reported pesticide exposure was assessed by whether the participant had ever handled the pesticide concentrate (for low dose chronic exposure) or sought advice for pesticide poisoning (acute exposure) and participants categorised into those with only acute or chronic exposure, those with both acute and chronic exposure and those with neither acute nor chronic exposure. Associations between acute and chronic pesticide exposure, and screen-positive ill-health were determined after adjustment for demographic, lifestyle, occupation and somatic severity scores and other variables.
  
  
  RESULTS
  In those participants, who had never sought advice for pesticide poisoning, handling the pesticide concentrate for treating sheep was associated with elevated ORs for screen-positive neuropathy (ORadi 1.57 95%CI 0.97-2.54) and Parkinsonism (ORadj 1.56 95%CI 0.95-2.56) but not depression or dementia. In those participants who had handled the pesticide concentrate, seeking advice for pesticide poisoning was associated with screen-positive depression (Odds ratio, ORadj=9.97 95%CI 4.76-20.8 ), dementia (OR=6.94 95%CI 3.44-14.0), Parkinsonism (ORadj=4.77 95% 2.39-9.52), and neuropathy (ORadj=4.77 95%CI 2.39-9.52). Adjustment for somatic severity score modified little the associations with pesticide handling in those not acutely exposed but reduced the ORs for seeking advice for pesticide poisoning in those exposed chronically. Furthermore, stratification of results based upon somatic severity score indicated that the highest ORs for handling the pesticide concentrate associated with neuropathy and Parkinsonism were found in those participants whose somatic score was minimal.
  
  
  CONCLUSIONS
  Results are consistent with low-dose exposure to pesticides being associated with screen-positive neuropathy and Parkinsonism but the stronger associations between seeking advice for pesticide poisoning and screen-positive ill-health suggest that acute pesticide exposure remains an important determinant of ill-health. Further work is required to better delineate to what extent low dose exposures may contribute to ill-health in populations without acute exposures. Somatising tendency does not appear to play an important role in this population.
authors.affiliation: Centre for Occupational and Environmental Health, Centre for Epidemiology, Institute of Population Health, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9PL, United Kingdom. Electronic address: a.povey@manchester.ac.uk.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Povey
authors.affiliation: Centre for Biostatistics, Institute of Population Health, Faculty of Medical and Human Sciences, University of Manchester, United Kingdom.
authors.forename: Roseanne
authors.initials: R
authors.lastname: McNamee
authors.affiliation: Centre for Occupational and Environmental Health, Centre for Epidemiology, Institute of Population Health, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9PL, United Kingdom.
authors.forename: Haytham
authors.initials: H
authors.lastname: Alhamwi
authors.affiliation: Centre for Occupational and Environmental Health, Centre for Epidemiology, Institute of Population Health, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9PL, United Kingdom.
authors.forename: S Jill
authors.initials: SJ
authors.lastname: Stocks
authors.affiliation: Centre for Occupational and Environmental Health, Centre for Epidemiology, Institute of Population Health, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9PL, United Kingdom.
authors.forename: Gillian
authors.initials: G
authors.lastname: Watkins
authors.affiliation: Institute of Brain, Behaviour and Mental Health, Faculty of Medical and Human Sciences, University of Manchester, United Kingdom.
authors.forename: Alistair
authors.initials: A
authors.lastname: Burns
authors.affiliation: Centre for Occupational and Environmental Health, Centre for Epidemiology, Institute of Population Health, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9PL, United Kingdom.
authors.forename: Raymond
authors.initials: R
authors.lastname: Agius
mesh_terms: D000383:Agriculture / Q000706:statistics & numerical data*; D000818:Animals; D001927:Brain Diseases / Q000139:chemically induced / Q000453:epidemiology*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D006801:Humans; D016015:Logistic Models; D001523:Mental Disorders / Q000139:chemically induced / Q000453:epidemiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D016017:Odds Ratio; D010575:Pesticides / Q000009:adverse effects*; D015995:Prevalence; D012756:Sheep; D011795:Surveys and Questionnaires; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D010575:Pesticides
keywords: Neuropsychiatric ill-health; Organophosphates; Pesticides