Tuesday, October 14, 2014
In Search of the Marijuana Breathalyzer
Pissing in a cup may be on the way out.
The good news: Marijuana breathalyzers are coming. The bad news: Marijuana breathalyzers are coming.
For years now, urinalysis using a mass spectrometer has been, if you’ll excuse the expression, the gold standard for drug testing. But in the case of alcohol, exhaled breath has always been the detection matrix of choice. And now, after the publication of several papers analyzing the detection of various drugs of abuse in exhaled breath, companies are hoping to leap into the market for cannabis breathalyzers.
A 2013 paper in the delightfully named Journal of Breath Research, written by neuroscience researchers at the Karolinska Institute in Stockholm, sought to confirm recent research suggesting that amphetamine, THC, and other drugs can be reliably detected in users who exhale into specially treated breath pads. The researchers collected breath, plasma, and urine samples from 47 patients. They tested for metabolites of methadone, amphetamine, morphine, benzodiazepines, cocaine, buprenorphine, and THC.
The results of the testing “provide further support to the possibility of using exhaled breath as a readily available specimen for drugs of abuse testing…. The detection rate for most investigated substances appears to be high, and higher than previously reported, with the exception of benzodiazepines.” The false positive rate was about 8%, which is very good, and is due, presumably, to improved sampling sensitivity.
In collaboration with Karolinska, NIDA researchers published a paper in Clinical Chemistry showing that cannabinoids blown onto breath pads were stable for up to 8 hours at room temperature—and up to 6 months in cold storage evidence lockers. The researchers tested 13 chronic smokers and 11 occasional smokers. Analysis of breath pad samples nailed all 13 of the serious smokers, and all but one of the casual smokers an hour after smoking. With current technology, the cannabis detection window remains very small, somewhere between 30 minutes and two hours. However, testing positive tells us nothing about when, and how much, marijuana was smoked.
Furthermore: “If a correlation to blood concentration can be shown for exhaled breath levels, it may become a substitute matrix for monitoring impairment.” And that, readers, is the Big If. What, exactly, are we testing FOR? Impairment, or just any and all use? Is there a reliable standard for marijuana, like the 0.08 blood level standard for alcohol? Or is a plethora of spurious positives on the horizon?
Roadside drug breathalyzers are presently under development or are in the prototype stage at several North American companies. One such device is a marijuana breathalyzer with a two-hour test window soon to be on offer from Cannabix Technologies. It was developed by a former member of the Royal Canadian Mounted Police because, says the company, there is no standardized way “to detect whether someone has been using marijuana on the spot like a breathalyzer does for alcohol.” So Cannabix is collaborating with Field Forensics Inc. to develop a testing device for roadside use.
An analysis last month at MarketWatch.com saw a silver lining in the Cannabix breathalyzer, calling it “possibly the next major step towards normalization of more widespread marijuana use being allowed as such a device would offer a ready means of addressing key sticking points that have kept industry, legislators and law enforcement from agreeing on how best to regulate cannabis.”
North America is viewed as a “target-rich market” that is “ripe for the advent of a pot breathalyzer.” In the end, “roadside blood draws by law enforcement and other invasive methods of screening for THC intoxication, like zero-tolerance urine testing at the workplace, are increasing impractical as medical and even recreational cannabis gain ground throughout North America.”
The coming cannabis breathalyzers will be able to tell us the “when.” And soon they may even be able to tell us how much. But it remains unclear whether marijuana breathalyzers will ever be able to tell us how high—to reliably measure cannabis impairment behind the wheel. Somewhat mysteriously, the level of 5 nanograms of THC per blood milliliter has emerged as the de facto standard. But it’s clear to people who are actually familiar with marijuana’s effects that experienced users don’t react the same way as naïve users, and it’s perfectly logical to presume that some users can drive with complete safety at the 5ng level—users such as daily consumers of medical cannabis, whose tolerance is high even though daily quantities smoked is usually low.
One inspiration behind the cannabis breathalyzer is law enforcement’s love of the alcohol breathalyzer. In 1938, Dr. Rolla Harger of Indiana University introduced his Drunkometer, the first device for testing alcohol on a person’s breath. But it wasn’t portable. And it wasn’t until 1954 that Indiana University’s Robert Borkenstein came up with the portable Breathalyzer. The rest is drunk driving history.
In the bad old days before anybody “blew” a 0.08, prosecuting a DUI required court evidence—dash cam footage, field sobriety tests, officer assessments and testimony, and on and on. At present, that’s the situation for law enforcement when it comes to prosecuting a DUI for marijuana. For years, the prevailing court test has been the Duquenois-Levine test—the dominant method for field-testing marijuana since 1930—and it is considered by many to be wildly inaccurate. It involves inserting a bit of the substance in question into a prepared pipette, then waiting to see if it turns purple. If it does, the suspect can be charged with possession. (One U.S. Superior Court judge referred to the test as “pseudo-scientific”).
According to the official drug policy of the United Nations, a positive marijuana ID requires gas chromatography/mass spectrometry analysis. But even sophisticated tests have angered courts, due to the DEA’s muddled standards for lab protocols. A former FBI agent told the Texas Tech Law Review: “We are arresting vast numbers of citizens for possession of a substance that we cannot identify by utilizing the forensic protocol that is presently in use in most crime labs in the United States.”
Russ Belville, writing at the Huffington Post, concludes in a similar vein: “Until science shows a reliable test that only snares pot-impaired drivers and not unimpaired drivers who happen to be pot smokers, [prosecutors] are just asking for an easier way to discriminate against legal cannabis consumers.”
Photo Credit: http://www.thcfinder.com/