PEPA-19

30TH ANNIVERSARY CRIME PREVENTION GUIDE 44 Cannabis and driving Many drugs impair one’s ability to drive. Depending on the drug type, it can reduce alertness, alter depth perception, impair concentration and attention span, slow reaction time, and affect motor skills and visual function. Many people think driving under the influence of cannabis is risk-free, and that drivers on cannabis are more cautious and driver slower. But studies show that cannabis can have a negative impact on driving, including reduced concentration and attention span, slower reaction time, and an altered perception of time and distance. Driving studies (simulated and on-road) showed drivers had increased variability in lane position, following distance and speed following cannabis use. Cannabis also affected driver ability to react to unexpected events, such as a pedestrian darting out onto the roadway. (Source: Clearing the Smoke on Cannabis Cannabis Use and Driving – An Update. Canadian Centre on Substance Use and Addiction. Douglas J. Beirness, Ph.D., Senior Research Associate, CCSA, Amy J. Porath, Ph.D., Director, Research and Policy, CCSA.) Mixing cannabis with alcohol greatly increases the negative impact on driving skills. A recent study comparing British Columbia roadside survey results with post-mortem data on fatally-injured drivers reported that cannabis use alone increased the risk of a fatal crash fivefold and that cannabis use, when combined with alcohol, increased the risk fortyfold. (Source: A comparison of drug use by fatally-injured drivers and drivers at risk. D. Beirness & E Beasley & P. Boase. Canadian Centre on Substance Use and Addiction, and Transport Canada. Proceedings of the 20th International Conference on Alcohol, Drugs and Traffic Safety, 2013,) How risky is driving after cannabis use? Estimates vary on the relative risk of crash associated with cannabis use.While there needs to be additional research in this area, studies and surveys over the past several years do indicate an increased risk of crash following cannabis use. • A 2012 analysis showed that acute cannabis consumption doubled the risk of a fatal or serious injury crash. (Source: M.Asbridge, J. Hayden & J. Cartwright,“Acute cannabis consumption and motor vehicle collision risk: A systematic review of observational studies and meta-analysis” (2012) 344 British Medical Journal e536.) • A second 2012 analysis reported that cannabis consumption more than doubled the risk of a crash, and that the crash risk increased with the amount consumed and the frequency of use. (Source: M. Li et al., “Marijuana Use and Motor Vehicle Crashes” (2012) 34 Epidemiologic Reviews 65, at 69.) • A recent study comparing British Columbia roadside survey results with post-mortem data reported that cannabis use alone increased the risk of a fatal crash fivefold and that cannabis use, when combined with alcohol, increased the risk fortyfold. (Source: A comparison of drug use by fatally-injured drivers and drivers at risk. D. Beirness & E Beasley & P. Boase. Canadian Centre on Substance Use and Addiction, and Transport Canada. Proceedings of the 20th International Conference on Alcohol, Drugs and Traffic Safety, 2013) Studies estimating the number of crash deaths attributable to cannabis are concerning. • One study estimated that, in 2012, there were 75 cannabis-attributed crash deaths in Canada. (Source:The Impact of Cannabis on Road Safety in the Canadian Provinces: Estimates of Collisions, Casualties and Costs in 2012. A.Wettlaufer et al., (Ottawa: Canadian Centre on Substance Abuse, 2016, at 13) • Another study estimated that there were between 89 and 267 cannabis-related crash deaths in 2010. (Source: Crude estimates of cannabis-attributed mortality and morbidity in Canada - implications for public health focused intervention priorities (2015) B. Fischer et al., 10 Journal of Public Health 1, at 2) www.freepik.com/free-photos-vectors/car">Car photo created by freepik (continued)

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