The Fight for Roadside Marijuana Detection Technologies
“Regulate Marijuana Like Alcohol” was the tag line for the legalization campaign in Colorado. While the comparison to alcohol regulation made it possible for the public to accept the idea of legalizing marijuana, when we asked the public to “treat marijuana like alcohol”, the public agreed and asked, “Where’s the marijuana Breathalyzer?” Now we are witnessing a scramble by drug detection technology companies to answer that question.
A new study in the Journal of Clinical Chemistry entitled “Cannabinoids in Exhaled Breath following Controlled Administration of Smoked Cannabis” found that someone who has smoked pot within a half-hour to two hours will exhale measurable amounts of active THC. All thirteen chronic pot smokers tested had positive breath tests 53 minutes after smoking a 6.8% THC joint, over half were positive after two hours, but only one was positive after four hours. Among eleven infrequent tokers tested, ten of them tested positive within the hour and seven of them still tested positive after ninety minutes.
These are preliminary experiments and there are still problems with the technology. The breath tests for THC, unlike the alcohol Breathalyzer, don’t tell how much THC is one’s system, only that there is some active THC in one’s system. Thus, it wouldn’t answer any questions about whether a particular driver is over a 5 nanogram per se limit, as exists in Washington and Colorado. However, it would be proof of violating a zero tolerance limit, as exists in over a dozen states. In any state, a future THC Breathalyzer would probably be reason enough for a police officer to arrest you under suspicion of DUI and take you in for the blood test.
But soon, there may not even be the need to “take you in”. Another technology, called the V-Chip, is being developed by Lidong Qin, Ph.D. and Ping Wang, Ph.D. of the Houston Methodist Research Institute. They received a $2.1 million grant from National Institute on Drug Abuse to develop a pocket-sized drug test for hospital emergency rooms that is fast, easy, and accurate.
The V-Chip is about the size of a credit card and contains antibodies to fifty different drugs and drug metabolites. Add a drop of blood, serum, urine, or other body fluid to the chip and any drug or metabolite within binds to the antibodies and causes a reaction that creates a visual bar graph of the substances detected. Tests show the V-Chip is accurate to the nanogram-per-milliliter level, which is exactly the standard used to determine THC levels in Washington and Colorado, as well as Nevada, Ohio, and Pennsylvania.
Once the V-Chip is perfected, it is not difficult to imagine law enforcement clamoring for its use outside the emergency room and on the roadside. If a reliable technology exists to prove a driver is over a 5 nanogram limit during the police encounter, there will be political pressure to allow its use. Currently, drawing blood from a suspect still requires an arrest and a warrant, as courts have found it to be an invasive procedure requiring a higher burden of suspicion. But when the blood needed is no longer a test-tube-full drawn by a nurse with a long needle and instead becomes something as simple as the pin prick diabetics use to test their blood sugar, it’s only a matter of time before courts find the need for traffic safety outweighs the slight inconvenience of a pin prick.
The roadside detection technologies are coming, but the biggest problem with them isn’t whether they’re accurate, it’s whether they’re actually telling us anything useful. The reason the alcohol Breathalyzer is a successful technology is because it tells us how much alcohol is actively impairing a driver and it gives a reliable indicator of how impaired the driver is in a dose dependent fashion. Yes, there are the extremes of the petite woman who’s too drunk to drive at .04 BAC and the obese alcoholic who can pass a driving test at .15 BAC, but by and large, people blowing .08 BAC are too drunk to drive and people who drink X drinks per hour at Y body weight are going to end up drunk.
Marijuana doesn’t work that way. Even the National Highway Traffic Safety Administration admits “It is difficult to establish a relationship between a person’s THC blood or plasma concentration and performance impairing effects. Concentrations of parent drug and metabolite are very dependent on pattern of use as well as dose. It is inadvisable to try and predict effects based on blood THC concentrations alone.” All the future marijuana Breathalyzer and V-Chip can tell us is if someone has used marijuana recently, not whether that use has rendered them unfit to drive.
But will that be enough for the general public to support? It will be hard to argue to the mainstream that someone can smoke a joint and safely get behind the wheel within an hour, even if it may be true. By legalizing marijuana with comparisons to alcohol, we may have unfortunately locked ourselves into a frame that demands an alcohol solution.