A Marijuana Breathalyzer Is in the Works. Should Science Treat Marijuana at Par With Alcohol?


Oct 7, 2022


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Detecting drugs in individuals behind the wheel has proven problematic for authorities in the past. However, scientists are now hoping to change that. A team of researchers at UCLA and ElectraTect, a UCLA startup, are working on refining a new device that detects THC or tetrahydrocannabinol—the chemical component in marijuana—in exhaled breath, bringing the world a step closer to a handheld marijuana breathalyzer. 

However, there’s a complex relationship between marijuana and mass incarceration that relies on the notion of treating marijuana as a public health problem. A tool that enables easier detection without conclusive evidence about the magnitude of the health concern it seeks to alleviate could only compound this relationship.

The new paper, published in the journal Organic Letters, explains that the device works in a similar manner to modern alcohol breath analyzers. Ethanol is oxidized into an organic chemical compound, a process that produces an electric current and helps in the detection of alcohol in the breath. The UCLA device subjects samples in a solution to oxidation, removing a hydrogen molecule from THC and generating an electric current that can be measured. A stronger current indicates a higher concentration of THC molecules in the sample. 

Amid a spate of marijuana decriminalization in many US states, with other countries following suit, the scientists believe such a breath analyzing tool could help make roadways safer. However, research seems to be divided on whether marijuana use is directly linked to an impaired driving ability. While some studies have linked blood concentration of THC to road accidents, reports suggest it’s more complicated than that. In light of contradictory research and inconclusive evidence, the development of a marijuana breathalyzer prompts the question: Should marijuana be treated at par with alcohol? And the question becomes more fraught when considering the high rate of criminalization of marginalized people for possessing marijuana.

The decriminalization movement has been gaining ground. However, introducing policing measures based on inconclusive or contradictory evidence could exacerbate cases of unfair law enforcement. The UCLA scientists stated that their device had the potential to improve unjust practices, usually compounded by the difficulties in detecting THC in drivers. While urine and blood tests are currently used to detect THC concentration, these tests are difficult to administer and are not always useful in identifying impaired drivers. “This ambiguity can lead to fines, imprisonment or loss of employment, even if an individual is not high when tested,” they wrote

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But here’s what we know about how marijuana really affects drivers. The effects of alcohol have been heavily researched, with limits being set on consumption before driving. In India, blood alcohol content must be within 0.03% per 100ml of blood. However, ascertaining the permissible amounts of marijuana consumption has proven to be more difficult. 

Researchers in Germany conducted a review of studies on cannabis use and car accidents in 2021. They found that “While some studies showed a significant correlation between high THC blood concentrations and accidents, most did not support the correlation at lower concentrations.” 

Research published in the American Journal on Addictions in 2010 analyzed the effects of cannabis compared with alcohol on driving, highlighting the three types of studies performed to assess risks. The first, cognitive studies, found marijuana use caused impairments in many performance areas including tracking, motor coordination and visual functions. However, users suffered no impairment in reaction times.

On the other hand, experimental studies that use driving simulations showed marijuana consumption had only “modest impairments” on actual road tests. Experienced smokers showed “almost no functional impairment”, except when combined with alcohol. 

Epidemiological studies, that try to assess the actual risk that a driver may cause an accident while driving under the influence, were found to be “inconclusive”, in contrast with the consensus that exists on alcohol use and increased crash risk. The study concluded that cannabis effects vary much more on an individual basis than with alcohol. 

“…More complex tasks that require conscious control are less affected, which is the opposite pattern from that seen with alcohol. Because of both this and an increased awareness that they are impaired, marijuana smokers tend to compensate effectively for their impairment by utilizing a variety of behavioral strategies such as driving more slowly, passing less, and leaving more space between themselves and cars in front of them,” the study noted.

A distinction has also been drawn between the medical and recreational use of marijuana. A study led by the Lambert Initiative for Cannabinoid Therapeutics at the University of Sydney and published in the Journal of the American Medical Association found that cannabidiol (CBD), a component of cannabis used for medical purposes, does not impair driving. It further revealed that  moderate amounts of THC produced mild driving impairment lasting up to four hours. 

The contradictions across several studies pose significant issues when it comes to drafting evidence-based policies to regulate drug use. Road safety is a growing concern across the world, with around 1.3 billion people dying in accidents each year. However, the history of drug policing is rife with mass incarceration and harsh punitive measures that also stigmatized access to support. An instrument like a breathalyzer could then be an intervention with unforeseen effects—and it discounts the fact that there’s no consistent way to assess marijuana impairment.

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A 2018 International Drug Policy Consortium (IDPC) report found that 1 in every 5 prisoners were arrested for drug offenses, with 83% languishing in prison for drug use or possession for personal use. It also highlighted how prohibitory measures had done little to curtail consumption, with a 145% increase in drug-related deaths between 2008 and 2018. 

More recently, alternative reform measures are being adopted in many countries to address drug use. United States president Joe Biden announced the pardoning of thousands of citizens convicted of marijuana possession. In a statement, Biden said, “Sending people to prison for possessing marijuana has upended too many lives and incarcerated people for conduct that many states no longer prohibit. Criminal records for marijuana possession have also imposed needless barriers to employment, housing, and educational opportunities.  And while white and Black and brown people use marijuana at similar rates, Black and brown people have been arrested, prosecuted, and convicted at disproportionate rates.”

Last year, the Union Ministry of Social Justice and Empowerment in India recommended decriminalizing possession of small quantities of drugs and avoiding prison time for users and individuals with substance use disorder. The Ministry also suggested prioritizing rehabilitation measures. 

Further, drug consumption and possession is a criminal offense under the Narcotic Drugs and Psychotropic Substances (NDPS) Act (1985). Critics have pointed out that the Act “makes no distinction between addicts, first-time users and recreational users.” This, in turn, raises the conviction rates. A 2020 Vidhi Centre for Legal Policy report revealed arrests for personal consumption accounted for 97.7% of NDPS cases in Maharashtra in 2017, and 97.3% in 2018. Studying the application of the NDPS Act in Mumbai, the report further highlighted, “An ill-conceived law that seeks to reform through punishment, in the hands of a police force pressed to increase its arrest rates, when brought before a judiciary rushed to close cases results in the inevitable: exploitation of the already marginalised.”

The UCLA scientists have admitted that a commercial breathalyzer is still a while away. Meanwhile, conflicting studies on marijuana impairment reveal the need for greater research, if drug policing measures do not want to reinforce carceral systems.


Written By Ananya Singh

Ananya Singh is a Senior Staff Writer at TheSwaddle. She has previously worked as a journalist, researcher and copy editor. Her work explores the intersection of environment, gender and health, with a focus on social and climate justice.


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