Since 1996, 21 states have approved the legalization of marijuana for medical use. More recently, Washington and Colorado have legalized the use of recreational marijuana, with California and Oregon not far behind. The health risks associated with marijuana have been well documented in a number of studies, but these are secondary to the much greater mortality risk associated with an increased prevalence of the drug: driving under the influence.
As is evident with alcohol, which in 2012 was responsible for 31% of the 10,000+ traffic fatalities in the United States, marijuana legalization will surely contribute to an increase in the number of impaired drivers and resultant accidents. According to a study in the American Journal of Epidemiology, between 1999 and 2010 the percentage of vehicular deaths involving marijuana increased from 4.2% to 12.2%, putting marijuana second behind alcohol in terms of substance-induced traffic fatalities.
Given the trending legislation toward increasing access to marijuana, both medical and recreational, we as a responsible civilian body must anticipate the impending need for intelligent regulation. As with alcohol, it will be important to establish a level of usage which we deem appropriate to still safely operate a vehicle, and to create a reliable technology that can help law enforcement detect this level with high specificity and sensitivity.
The challenge of establishing a limit is that every individual has a different level at which they are too intoxicated to operate a vehicle. This is largely due to the development of tolerance, either genetically or more commonly through previous use, which significantly impacts the user’s level of functionality. However, given that we have not let this deter us from creating a similar limit for alcohol, a limit for marijuana is on the way. In fact, some states have already established their own limits: Washington and Colorado currently use a level of 5 ng/dl in the blood.
Currently, a blood test is the most accurate means of determining acute marijuana usage, but this is not entirely useful to law enforcement due to the obvious logistical hurdles of analyzing the sample. More practical, as we have for alcohol, would be a breathalyzer that could easily tell if someone had any drug in their system, and more importantly, if they had used the drug recently (given its lipophilic qualities, marijuana can be detected several weeks later, which would confound immediate results and create false positives for acute use).
As of today, the leading company in the development of a marijuana breathalyzer is the Canadian group Cannabix Technologies, which has secured a Canadian patent and is in the process of doing so in the United States as well. Results of prototype testing are yet to be fully released, but the product will likely disclose acute marijuana usage in the scale of a few hours.
Given the historical trends in marijuana legalization, first medically and more recently recreationally, it is inevitable that regulation is the next big step in marijuana policy. It will be critical for the public health community to anticipate the surge in marijuana intoxication and motor vehicle accidents, and to accordingly encourage and support the development of necessary means of safety enforcement through research and technology.
Abraar Karan is a medical student who blogs at Swasthya Mundial. He can be reached on Twitter @AbraarKaran.