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Abstract
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The world‐wide debate on the legal status of cannabis continues, with potential therapeutic benefits leading to approval for medical use. In the United States, four states and the District of Columbia recently legalized recreational marijuana, while use has been legal in Uruguay since 1974.
The three primary reasons for concern about legalized cannabis are: evidence that cannabis may adversely affect the developing brain's neural connections 1, an increase in treatment requests for cannabis dependence occurring in the United States and the safety consequence of increased incidence of cannabis intoxication, particularly when driving.
In 2012, recreational cannabis use was legalized in Washington State. From 2009-12, 19.1% of suspected impaired drivers were positive for ∆9‐tetrahydrocannabinol (THC). This increased to 24.9% in 2013, while there were no changes in prevalence of alcohol or other psychoactive drugs 2. In the 2007 National Roadside Survey, 8.6% of weekend night‐time drivers were THC‐positive; in 2013-14, 12.6% were positive 3.
We have recently reviewed laboratory‐based, on‐the‐road driving and epidemiological data demonstrating cannabis‐impaired driving 4. THC blood concentrations increase rapidly during smoking, peak prior to the last puff, and decrease quickly, providing a short detection window of < 6 hours in occasional cannabis smokers 5. Blood collection delays, generally 1.5-4 hours, reduce detection rates. It is also worth noting that in early traffic crash culpability studies, where the percentage of cannabinoid‐positive drivers were compared with cannabinoid‐negative drivers, the inactive metabolite, 11‐nor‐9‐carboxy‐THC (THCCOOH), was used, which contributed to the failure to find evidence for an effect of cannabis.
Keywords: Cannabis impaired driving
Language: en |