title: Expert assessment of historical crop specific pesticide use in the Netherlands.
abstract: OBJECTIVE
  Retrospective assessment of environmental pesticide exposure is challenging. Exposure measurements or information on crop-specific pesticide use are often lacking historically. We applied expert assessment to reconstruct historical pesticide use patterns in the Netherlands, and evaluated reliability and accuracy of this procedure.
  
  
  METHODS
  For six main crops in the Netherlands, two experts per crop individually rated the probability (percentage of farmers applying) and frequency of use of authorised active ingredients between 1961 and 2005 per 5-year period. Inter-rater agreement was investigated by the percentage overall agreement and weighted Cohen's κ's (κ(w)). Experts' ratings were compared with self-reported pesticide use from recent farmer surveys to determine accuracy of the ratings.
  
  
  RESULTS
  Inter-rater agreement on the probability of use varied between crops (κ(w) 0.25 to 0.69), as well as agreement on the frequency of use (κ(w) 0.32 to 0.64). Inter-rater agreement was marginally higher for herbicides and fungicides than insecticides. Comparisons with survey data indicated fair to good accuracy of the experts' ratings for the probability (κ(w) 0.48 to 0.65) and frequency of use (κ(w) 0.38 to 0.68). For all crops except fruit, the specificity of the experts' ratings was higher than the sensitivity.
  
  
  CONCLUSIONS
  Overall inter-rater agreement between experts was fair to good and experts' ratings were reasonably accurate. Results of this study indicate that expert assessment can be used to derive information on historical pesticide use, which is essential for epidemiological studies evaluating the effect of (past) environmental exposure to pesticides on health.
authors.affiliation: Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands.
authors.forename: Maartje
authors.initials: M
authors.lastname: Brouwer
authors.affiliation: Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands.
authors.forename: Anke
authors.initials: A
authors.lastname: Huss
authors.affiliation: Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands Julius Centre for Public Health Sciences and Primary Care, University Medical Centre Utrecht, Utrecht, The Netherlands.
authors.forename: Roel
authors.initials: R
authors.lastname: Vermeulen
authors.affiliation: St. Elisabeth Hospital Tilburg, Tilburg, The Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: Nijssen
authors.affiliation: Institute of Environmental Sciences, Leiden University, Leiden, The Netherlands.
authors.forename: Geert
authors.initials: G
authors.lastname: de Snoo
authors.affiliation: Division of Environmental Epidemiology, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands.
authors.forename: Hans
authors.initials: H
authors.lastname: Kromhout
mesh_terms: D000383:Agriculture / Q000706:statistics & numerical data*; D004781:Environmental Exposure; D006801:Humans; D009426:Netherlands; D010575:Pesticides
chemical_list: D010575:Pesticides