Against a backdrop of clarity about the dangers of driving under the influence of alcohol, questions have rightfully been raised in the general community about the impact of marijuana use on driving performance and the risk of motor vehicle accidents. Although research examining this issue has gained momentum in recent years, the picture remains muddied by inconsistent findings and methodologies. A potentially alarming consequence of this muddied view may be evident in the findings of a recent study suggesting that young people perceive the negative consequences of driving after marijuana use as less likely than those of driving after alcohol use, and that such perceptions are associated with increased engagement in, and frequency of, driving under the influence of marijuana.1
The current literature review explores briefly the current state of research in the area of marijuana and driving, and looks toward a future of coherence and enlightenment.
prevalence of driving under the influence of marijuana
Results from the 2007 National Drug Strategy Household Survey (NDSHS)2 indicate that 2.9% of Australians aged at least 14 years have driven a motor vehicle while under the influence of illicit drugs in the last 12 months. This percentage has reduced from 3.9% and 3.3% in the 2001 and 2004 versions of the survey, respectively.3,4 These results are similar to those found in United States’ national substance use surveys, where 4.4% and 4.3% of respondents in 2004 and 2005, respectively, reported having driven under the influence of illicit drugs in the last 12 months.5
Relating to marijuana in particular, several researchers have surveyed the general driving population about their use of the drug prior to driving. Three Canadian studies have shown drivers to report having driven a vehicle during the previous 12 months under the influence of marijuana at rates of 1.5% to 2.9%.6-8 A recent review of drug use, impaired driving and traffic accidents by the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA)9 revealed that between 0.3% and 7.4% of drivers tested positive for marijuana across seven roadside surveys conducted between 1997 and 2007 in Australia, Denmark, the Netherlands, Norway, the United Kingdom, and the United States, using blood, urine or saliva tests (3.9% on average; Australia had the lowest rate among these studies).
In Scotland, researchers found that, among 537 drivers surveyed at toll bridges, 15% of 17 to 39 year-olds and 3% of over 40 year-olds reported having ever driven within 12 hours after using marijuana.10 Among students with drivers’ licences in Canada, these rates were as high as 19.7%.7,11 In British studies of youthful populations with drivers’ licences, self-reported rates of having ever driven under the influence of marijuana were 59% for dance- or night-club patrons10 and 40% for university students.12
– See more at: http://learnaboutmarijuanawa.org/factsheets/driving.htm#sthash.FUhZu8zi.dpuf