Cannabis use and self-reported collisions in a representative sample of adult drivers

Social, Prevention and Health Policy Research, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
Journal of Safety Research (Impact Factor: 1.29). 02/2007; 38(6):669-74. DOI: 10.1016/j.jsr.2007.09.004
Source: PubMed


This study examines the relationships between collision involvement and several measures of cannabis use, including driving after using cannabis, among drivers, based on a population survey of Ontario adults in 2002 and 2003.
Logistic regression analyses examined self-reported collision involvement in the last 12 months by lifetime use of cannabis, past year use of cannabis, and past year driving after using cannabis, while controlling for demographic characteristics.
We found that the odds of reporting collision involvement was significantly higher among cannabis users, and among those who reported driving after cannabis use. Some evidence for a dose-response relationship was seen as well.
Cannabis users and people who report driving after cannabis use are also more likely to report being involved in a collision in the past year. These observations suggest that collision prevention efforts could be aimed at these groups. Additional work to determine the causal pathways involved in the relationships observed here is needed.

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    • "While the importance of the role of economic evaluations in such a systematic assessment has been recognised, to date there has been no quantification of the significant costs and benefits of one legal option over the status quo. Past research has examined selected outcomes of a policy change; for example, the cost impacts on the criminal justice system [9], [16], [17], [18]; gains in taxation income [9], [16]; impacts on use [16], [19], [20]; on educational attainment [21], [22], [23]; and on driving [24], [25]. However, to our knowledge no previous research has combined and valued the wide range of costs and benefits of cannabis policies, nor included individuals’ costs and benefits. "
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    ABSTRACT: To date there has been limited analysis of the economic costs and benefits associated with cannabis legalisation. This study redresses this gap. A cost benefit analysis of two cannabis policy options the status quo (where cannabis use is illegal) and a legalised-regulated option was conducted. A cost benefit analysis was used to value the costs and benefits of the two policies in monetary terms. Costs and benefits of each policy option were classified into five categories (direct intervention costs, costs or cost savings to other agencies, benefits or lost benefits to the individual or the family, other impacts on third parties, and adverse or spill over events). The results are expressed as a net social benefit (NSB). The mean NSB per annum from Monte Carlo simulations (with the 5 and 95 percentiles) for the status quo was $294.6 million AUD ($201.1 to $392.7 million) not substantially different from the $234.2 million AUD ($136.4 to $331.1 million) for the legalised-regulated model which excludes government revenue as a benefit. When government revenue is included, the NSB for legalised-regulated is higher than for status quo. Sensitivity analyses demonstrate the significant impact of educational attainment and wellbeing as drivers for the NSB result. Examining the percentiles around the two policy options, there appears to be no difference between the NSB for these two policy options. Economic analyses are essential for good public policy, providing information about the extent to which one policy is substantially economically favourable over another. In cannabis policy, for these two options this does not appear to be the case.
    Full-text · Article · Apr 2014 · PLoS ONE
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    ABSTRACT: The prevalence of both alcohol and cannabis use and the high morbidity associated with motor vehicle crashes has lead to a plethora of research on the link between the two. Drunk drivers are involved in 25% of motor vehicle fatalities, and many accidents involve drivers who test positive for cannabis. Cannabis and alcohol acutely impair several driving-related skills in a dose-related fashion, but the effects of cannabis vary more between individuals than they do with alcohol because of tolerance, differences in smoking technique, and different absorptions of Delta(9)-tetrahydrocannabinol (THC), the active ingredient in marijuana. Detrimental effects of cannabis use vary in a dose-related fashion, and are more pronounced with highly automatic driving functions than with more complex tasks that require conscious control, whereas alcohol produces an opposite pattern of impairment. Because of both this and an increased awareness that they are impaired, marijuana smokers tend to compensate effectively while driving by utilizing a variety of behavioral strategies. Combining marijuana with alcohol eliminates the ability to use such strategies effectively, however, and results in impairment even at doses which would be insignificant were they of either drug alone. Epidemiological studies have been inconclusive regarding whether cannabis use causes an increased risk of accidents; in contrast, unanimity exists that alcohol use increases crash risk. Furthermore, the risk from driving under the influence of both alcohol and cannabis is greater than the risk of driving under the influence of either alone. Future research should focus on resolving contradictions posed by previous studies, and patients who smoke cannabis should be counseled to wait several hours before driving, and avoid combining the two drugs.
    Preview · Article · Jul 2009 · American Journal on Addictions

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