Current testing for marijuana intoxication levels has many drawbacks. The most effective and accurate test is to measure THC in blood or urine. But unlike alcohol, THC can remain in the bloodstream for weeks after use. A “positive” THC blood or urine test doesn’t necessarily identify recent use, making it near-impossible to develop an accurate roadside test akin to the Breathalyzer, which measures people’s blood alcohol levels and is primarily used by police during traffic stops where intoxication is suspected.
THC in saliva, however, more accurately reflects marijuana use within the previous 12 hours. Preliminary studies show scientists have found their rapid test could reliably and consistently detect THC in saliva in less than 5 minutes. Some existing saliva tests for THC have slow processing times or are restricted to yes/no results, like a pregnancy test.
Hakho Lee, the senior researcher on a new study based at Massachusetts General Hospital’s Center for Systems Biology in Boston, said his team has developed a test that quickly detects THC in saliva and quantifies the amount. Initial testing accurately picked out the THC in saliva samples from 43 marijuana consumers and 43 non-consumers. According to Lee, it took about 3 minutes from “sample in [to] result out.”
The test also showed that THC in saliva declined quickly after smoking the drug. However, six hours later, TCH levels remained above 1 ng/ml – the recommended cut-off from the European Driving Under the Influence of Drugs, Alcohol, and Medicines project.
The larger, looming, concern is that there is no set measure of THC level that is defined as “intoxication.” Lee explained that the level of actual impairment depends on how the cannabis is ingested and whether the person in question is a regular consumer of marijuana, among a myriad of other factors.
Lee remains confident that, with further refinement, his team’s rapid test could prove helpful for roadside testing of potentially impaired drivers.
Dr. Guohua Li, a professor at Columbia University Mailman School of Public Health in New York City, studies the role of drugs in traffic accidents and other injuries. Dr. Li was not involved in the research but views the initial results of testing as “very encouraging.”
As more states legalize marijuana and federal legalization appears to be imminent, its usage has increased. Li points out that, in the past few decades, there has been an increase in the number of fatally injured drivers who have THC in their systems. While not as dangerous as drunk driving, drivers who’ve used cannabis have, on average, approximately twice the risk as non-users of being in a fatal car accident.
“The evidence is overwhelming and consistent in showing a relationship between [marijuana] use and an increased risk of being involved in a fatal crash,” Li said. If you’re thinking of popping an edible before you head to family dinner or you’re considering lighting up your favorite hemp wraps as you go, it is never a good idea. Cannabis legalization is a positive thing for so many reasons, for so many people, but there is no denying the dangers posed by smoking and driving. Please always use cannabis responsibly.
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