title: Concentrations and environmental risk of chlorothalonil in air near potato fields in Prince Edward Island, Canada.
abstract: BACKGROUND
  Chlorothalonil is used extensively in Prince Edward Island for the control of blight on potatoes, and has been measured throughout summer months in ambient air monitoring studies. This study was designed to characterize near-field drift of chlorothalonil, and to evaluate how exposure to measured air concentrations might impact upon local wildlife species.
  
  
  RESULTS
  Air samples were collected using high-volume samplers at three distances downwind of sprayed potato fields, and at four different time intervals. Chlorothalonil was detected in 73% of prespray samples (from < 0.013 to 0.440 µg m(-3)). The mean air concentration 0 m away from the field edge during spray was 5.8 µg m(-3), which was 7-41 times higher than concentrations measured in similar studies. Air concentrations were found to decline exponentially both with distance and time, although 0 m and 30 m concentrations at 2 h post-spray remained significantly (3 times) higher than prespray (P < 0.05). Wind speed was not found to be significantly correlated with air concentration; however, increases in temperature were found to be significantly correlated with increases in air concentrations at all sample times, at 0 m and 30 m distances.
  
  
  CONCLUSIONS
  Frequent prespray detections and high post-spray concentrations suggest that both chronic and acute exposures to non-target species are occurring; however, risk calculations suggest a relatively low risk of effects to representative species. One measurement showed that a human-health-based short-term guideline had been exceeded, indicating that potential impacts to humans from chlorothalonil under current application conditions cannot be discounted.
authors.affiliation: Science and Technology Branch, Environment Canada, Atlantic Region, Dartmouth, NS, Canada. christine.garron@ec.gc.ca
authors.forename: Christine
authors.initials: C
authors.lastname: Garron
authors.forename: Bill
authors.initials: B
authors.lastname: Ernst
authors.forename: Gary
authors.initials: G
authors.lastname: Julien
authors.forename: René
authors.initials: R
authors.lastname: Losier
authors.forename: Kimberly
authors.initials: K
authors.lastname: Davis
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution; D002170:Canada; D004781:Environmental Exposure; D004784:Environmental Monitoring; D005659:Fungicides, Industrial / Q000032:analysis* / Q000494:pharmacology; D009570:Nitriles / Q000032:analysis*; D055750:Phytophthora infestans / Q000187:drug effects / Q000502:physiology; D010935:Plant Diseases / Q000382:microbiology*; D011325:Prince Edward Island; D011198:Solanum tuberosum / Q000254:growth & development / Q000382:microbiology*
chemical_list: D000393:Air Pollutants; D005659:Fungicides, Industrial; D009570:Nitriles; C005806:tetrachloroisophthalonitrile