title: The use of self-reported symptoms as a proxy for acute organophosphate poisoning after exposure to chlorpyrifos 50% plus cypermethrin 5% among Nepali farmers: a randomized, double-blind, placebo-controlled, crossover study.
abstract: Previous studies stating a high prevalence of occupational acute pesticide poisoning in developing countries have mainly relied on measurements of the rather non-specific self-reported acute pesticide poisoning symptoms. Only a few studies have measured the biomarker plasma cholinesterase (PchE) activity, in addition to the symptoms, when assessing occupational acute pesticide poisoning. This study evaluated self-reported symptoms as a proxy for acute organophosphate poisoning among Nepali farmers by examining self-reported acute organophosphate poisoning symptoms and PchE activity in response to occupational acute organophosphate exposure.
  
  
  
  We performed a randomized, double-blind, placebo-controlled, crossover trial among 42 Nepali commercial vegetable farmers. The farmers were randomly assigned (ratio 1:1) to a 2-h organophosphate (chlorpyrifos 50% plus cypermethrin 5%: moderately hazardous) spray session or a 2-h placebo spray session, and after 7 days' washout, the farmers were assigned to the other spray session. Before and after each spray session farmers were interviewed about acute organophosphate poisoning symptoms and PchE activity was measured. Analyses were conducted with a Two Sample T-test and Mann Whitney U-test.
  
  
  
  We found no difference in the symptom sum or PchE activity from baseline to follow up among farmers spraying with organophosphate (symptom sum difference -1, p = 0.737; PchE mean difference 0.02 U/mL, p = 0.220), placebo (symptom sum difference 9, p = 0.394; PchE mean difference 0.02 U/mL, p = 0.133), or when comparing organophosphate to placebo (symptom p = 0.378; PchE p = 0.775). However, a high percentage of the farmers reported having one or more symptoms both at baseline and at follow up in the organophosphate spray session (baseline 47.6%, follow up 45.2%) and placebo spray session (baseline 35.7%, follow up 50.0%), and 14.3% of the farmers reported three or more symptoms after the organophosphate spray session as well as after the placebo spray session.
  
  
  
  We found a general presence of acute organophosphate symptoms among the farmers regardless of organophosphate exposure or poisoning. Thus, self-reported acute organophosphate symptoms seem to be a poor proxy for acute organophosphate poisoning as the occurrence of these symptoms is not necessarily associated with acute organophosphate poisoning.
  
  
  
  ClinicalTrials.gov, NCT02838303 . Registered 19 July 2016. Retrospectively registered.
authors.affiliation: Department of Occupational and Environmental Medicine, Bispebjerg Frederiksberg Hospital, University of Copenhagen, Bispebjerg Bakke 23, Entrance 20F, 2400, Copenhagen NV, Denmark. dea_kofod@hotmail.com.|Department of Occupational and Environmental Medicine, Odense Hospital, University of Southern Denmark, Odense, Denmark. dea_kofod@hotmail.com.
authors.forename: Dea Haagensen
authors.initials: DH
authors.lastname: Kofod
authors.affiliation: Department of Occupational and Environmental Medicine, Odense Hospital, University of Southern Denmark, Odense, Denmark.|International Centre for Occupational, Environmental and Public Health (ICOEPH), Odense Hospital, University of Southern Denmark, Odense, Denmark.|, Dialogos, Noerrebrogade 52C, Copenhagen N, Denmark.
authors.forename: Erik
authors.initials: E
authors.lastname: Jørs
authors.affiliation: Department of Occupational and Environmental Medicine, Bispebjerg Frederiksberg Hospital, University of Copenhagen, Bispebjerg Bakke 23, Entrance 20F, 2400, Copenhagen NV, Denmark.|International Centre for Occupational, Environmental and Public Health (ICOEPH), Odense Hospital, University of Southern Denmark, Odense, Denmark.|, Dialogos, Noerrebrogade 52C, Copenhagen N, Denmark.
authors.forename: Anshu
authors.initials: A
authors.lastname: Varma
authors.affiliation: Institute of Medicine, Tribhuvan University of Nepal, Kathmandu, Nepal.
authors.forename: Shankuk
authors.initials: S
authors.lastname: Bhatta
authors.affiliation: Department of Occupational and Environmental Medicine, Bispebjerg Frederiksberg Hospital, University of Copenhagen, Bispebjerg Bakke 23, Entrance 20F, 2400, Copenhagen NV, Denmark.|International Centre for Occupational, Environmental and Public Health (ICOEPH), Odense Hospital, University of Southern Denmark, Odense, Denmark.
authors.forename: Jane Frølund
authors.initials: JF
authors.lastname: Thomsen
mesh_terms: D000328:Adult; D004390:Chlorpyrifos; D002802:Cholinesterases / Q000097:blood*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D000067565:Farmers; D006801:Humans; D007306:Insecticides / Q000506:poisoning*; D008297:Male; D008875:Middle Aged; D009390:Nepal; D062025:Organophosphate Poisoning / Q000097:blood*; D011722:Pyrethrins / Q000506:poisoning; D057566:Self Report
chemical_list: D007306:Insecticides; D011722:Pyrethrins; C017160:cypermethrin; D002802:Cholinesterases; D004390:Chlorpyrifos
keywords: Acute pesticide poisoning; Farmers; Nepal; Organophosphate; Plasma cholinesterase; Symptoms