The usage of cannabis for medical and recreational purposes is allowed in most states in the U.S. However, ensuring road safety remains a priority for all states. To effectively identify individuals who recently consumed cannabis and prevent impaired driving, the development of a reliable breathalyzer is crucial. However, creating a breathalyzer for cannabis is more challenging than for alcohol since the intoxicating component of cannabis, THC, is believed to be carried within aerosol particles exhaled by individuals. The total volume of these aerosols is usually very small, making it difficult to accurately measure the THC content. Presently, there is no standardized method for accomplishing this.
Researchers at the National Institute of Standards and Technology (NIST) and the University of Colorado Boulder recently conducted a study published in the Journal of Breath Research. The study involved collecting breath samples from individuals both before and after they smoked high-THC cannabis, commonly known as marijuana. Laboratory instruments were utilized (not a handheld device) to measure the THC levels in the breath samples. The aim of this research was to establish a reproducible protocol that can provide consistent results, an essential step towards developing a reliable and validated field-based method.
The collection of breath samples before individuals smoked marijuana was significant because THC can remain in the bodies of frequent cannabis users for a month or longer, even after the drug’s effects have worn off. One crucial question that remains unanswered is whether breath measurements can distinguish between individuals who regularly use cannabis but have not consumed it recently and those who consumed it an hour ago. Having a reproducible protocol for breath measurements will assist not only the researchers involved in this study but also other scientists in answering that question.
The collection of breath samples took place in a mobile lab, specifically a well-equipped white van that conveniently parked outside the participants’ residences. The University of Colorado Boulder researchers, including Cinnamon Bidwell, an assistant professor of psychology and neuroscience and a co-author of the study, developed this mobile pharmacology lab. It allowed the researchers to conduct their study without violating federal laws or directly handling high-THC cannabis.
Participants in the study purchased and used a consistent type of high-THC cannabis from a licensed dispensary in Boulder, Colorado. This approach ensured standardized conditions for the research.
During the study, participants entered the van at the scheduled time and provided a pre-use breath sample as well as a blood sample. Subsequently, they returned to their homes, smoked cannabis according to their usual habits, and promptly went back to the van to provide a second blood sample. Comparing the before-and-after blood samples helped confirm that the participants had recently consumed cannabis since THC concentrations spike immediately after ingestion. An hour later, the participants provided their second breath sample.
To collect breath samples, participants exhaled into a tube containing an “impaction filter” that trapped aerosols from their breath. In the laboratory, the researchers extracted the captured material from the filter and used liquid chromatography with tandem mass spectrometry, a laboratory technique that identifies compounds and measures their concentration, to analyze the THC and other cannabis compounds.
Since this study focused on developing a protocol, the analysis results, involving 18 participants, do not possess statistical significance. Nevertheless, they underscore the need for further research.
“Our expectation was to observe higher THC concentrations in the breath samples collected an hour after cannabis use,” explained Lovestead. However, the THC levels displayed a similar range in both pre-use and post-use samples. Lovestead noted, “In many cases, based on the concentration of THC in their breath, we would not have been able to determine whether the person had smoked within the past hour.”
NIST materials research engineer and co-author Kavita Jeerage emphasized the necessity for more extensive research to establish the efficacy of a cannabis breathalyzer. Jeerage stated, “A breathalyzer test can significantly impact a person’s life, so it is crucial that people have confidence in the accuracy of the results.”