title: Estimating the harms and costs of cannabis-attributable collisions in the Canadian provinces.
abstract: In 2012, 10% of Canadians used cannabis and just under half of those who use cannabis were estimated to have driven under the influence of cannabis. Substantial evidence has accumulated to indicate that driving after cannabis use increases collision risk significantly; however, little is known about the extent and costs associated with cannabis-related traffic collisions. This study quantifies the costs of cannabis-related traffic collisions in the Canadian provinces.
  
  
  
  Province and age specific cannabis-attributable fractions (CAFs) were calculated for traffic collisions of varying severity. The CAFs were applied to traffic collision data in order to estimate the total number of persons involved in cannabis-attributable fatal, injury and property damage only collisions. Social cost values, based on willingness-to-pay and direct costs, were applied to estimate the costs associated with cannabis-related traffic collisions. The 95% confidence intervals were calculated using Monte Carlo methodology.
  
  
  
  Cannabis-attributable traffic collisions were estimated to have caused 75 deaths (95% CI: 0-213), 4407 injuries (95% CI: 20-11,549) and 7794 people (95% CI: 3107-13,086) were involved in property damage only collisions in Canada in 2012, totalling $1,094,972,062 (95% CI: 37,069,392-2,934,108,175) with costs being highest among younger people.
  
  
  
  The cannabis-attributable driving harms and costs are substantial. The harm and cost of cannabis-related collisions is an important factor to consider as Canada looks to legalize and regulate the sale of cannabis. This analysis provides evidence to help inform Canadian policy to reduce the human and economic costs of drug-impaired driving.
authors.affiliation: Canadian Centre on Substance Abuse, Canada; Centre for Addiction and Mental Health, Canada. Electronic address: AWettlaufer@ccsa.ca.
authors.forename: Ashley
authors.initials: A
authors.lastname: Wettlaufer
authors.affiliation: Centre for Addiction and Mental Health, Canada.
authors.forename: Roxana O
authors.initials: RO
authors.lastname: Florica
authors.affiliation: Dalhousie University, Canada.
authors.forename: Mark
authors.initials: M
authors.lastname: Asbridge
authors.affiliation: Canadian Centre on Substance Abuse, Canada.
authors.forename: Douglas
authors.initials: D
authors.lastname: Beirness
authors.affiliation: University of British Columbia, Canada.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Brubacher
authors.affiliation: University of Northern British Columbia, Canada.
authors.forename: Russell
authors.initials: R
authors.lastname: Callaghan
authors.affiliation: Centre for Addiction and Mental Health, Canada; Centre for Criminology and Sociolegal Studies, University of Toronto, Canada.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Fischer
authors.affiliation: Centre for Addiction and Mental Health, Canada; The University of New South Wales, Australia.
authors.forename: Gerrit
authors.initials: G
authors.lastname: Gmel
authors.affiliation: Centre for Addiction and Mental Health, Canada.
authors.forename: Sameer
authors.initials: S
authors.lastname: Imtiaz
authors.affiliation: Centre for Addiction and Mental Health, Canada.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Mann
authors.affiliation: Canadian Centre on Substance Abuse, Canada.
authors.forename: Anna
authors.initials: A
authors.lastname: McKiernan
authors.affiliation: Centre for Addiction and Mental Health, Canada.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Rehm
mesh_terms: D000063:Accidents, Traffic / Q000145:classification* / Q000191:economics / Q000401:mortality*; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002170:Canada; D002188:Cannabis / Q000009:adverse effects*; D002423:Cause of Death; D003365:Costs and Cost Analysis; D003430:Cross-Sectional Studies; D000066448:Driving Under the Influence / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000191:economics / Q000401:mortality*; D008875:Middle Aged; D014947:Wounds and Injuries / Q000191:economics* / Q000401:mortality*; D055815:Young Adult
keywords: Canada; Cannabis; Costs; Harm; Traffic collision