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Citation
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Windle SB, Sequeira C, Filion KB, Thombs BD, Reynier P, Grad R, Ells C, Eisenberg MJ. CMAJ 2021; 193(14): E481-E485. |
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Abstract
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KEY POINTS
Analyses of data suggest that legalization of recreational cannabis in United States jurisdictions may be associated with a small but significant increase in fatal motor vehicle collisions and fatalities, which, if extrapolated to the Canadian context, could result in as many as 308 additional driving fatalities annually.
Efforts to deter cannabis-impaired driving in Canada include the implementation of federal tetrahydrocannabinol driving limits (≥ 2 ng/mL) with associated penalties, the development of measures and tools for the detection of cannabis impairment, and public education about the risks of cannabis-impaired driving.
Health care professionals have an opportunity to educate patients about the safer use of cannabis products, including advising against cannabis use and driving (especially in combination with alcohol), with a suggested wait time of at least 6 hours before driving.
"Don't drive high." This is the message that the government of Canada wanted all drivers to take to heart after the legalization of recreational cannabis in October 2018. However, the association between the use of legal recreational cannabis and impaired driving is not clear. Although cannabis consumption has the potential to substantially impair psychomotor skills and cognitive functions -- reducing performance on critical tracking and divided-attention tasks, slowing reaction time and increasing lane weaving1 -- the influence of cannabis on driving tasks varies by individual, dose and methods of consumption, and time since consumption before driving.2 Some studies have found associations between cannabis use and impairment of driving -- including in driving simulators, closed-course driving and epidemiologic studies3 -- but others have not.4 Furthermore, the findings of studies are frequently confounded by users' consumption of cannabis with other legal (e.g., tobacco, alcohol) and illegal (e.g., opioids, methamphetamines) substances,3 making it difficult to estimate the relative contribution of cannabis consumption to motor vehicle collisions. This in turn leads to difficulty in establishing the optimal approach to educating both health care providers and the public about the effects of cannabis, so as to deter driving under the influence of cannabis.
We analyze the association between recreational cannabis legalization and fatal motor vehicle collision rates and discuss the implications of existing evidence for Canadian policy and physicians' practice.
Keywords: Cannabis impaired driving
Language: en |