Researchers Make Progress Toward Tricky Job Of Analyzing THC Levels In Breath Of Cannabis Smokers

In a recent study conducted by the National Institute of Standards and Technology (NIST) and the University of Colorado Boulder, researchers made strides in analyzing the presence of THC in the breath of cannabis smokers. THC is the intoxicating component of cannabis.

The study sought to develop a protocol that would yield reproducible results in an attempt to find a reliable field-based breathalyzer for cannabis.

While developing such a device is far more challenging than for alcohol due to the nature of THC-carrying aerosol particles, this research represents a crucial step toward ensuring road safety and accurately identifying impaired drivers. 

“One key question that we cannot yet answer is whether breath measurements can be used to distinguish between a person who uses cannabis regularly but hasn’t done so lately, and someone who consumed an hour ago,” said NIST supervisory chemical engineer and study author Tara Lovestead. “Having a reproducible protocol for breath measurements will help us and other researchers answer that question.” 

Challenges of Cannabis Breathalyzer Development: Unlike alcohol, THC is carried within small aerosol particles in the breath, making it difficult to accurately measure its content. This poses a significant challenge in the development of a cannabis breathalyzer. Current methods lack standardization, and there is a need to establish a protocol that consistently delivers reliable results.

Study Methodology and Findings

In the study, breath samples were collected from individuals both before and after smoking high-THC cannabis. Researchers used lab instruments to measure THC concentration in the samples. Notably, the study utilized a mobile pharmacology lab, a comfortable white van parked conveniently outside participants' homes. This approach enabled the researchers to conduct their studies without handling high-THC cannabis, adhering to federal laws.

To establish a baseline, breath samples were collected before participants smoked, as THC remains in the system of cannabis users for extended periods. The study aimed to determine whether breath measurements could distinguish between individuals who had recently consumed cannabis and those who had not used it for an extended period.

The participants provided breath samples by exhaling into a tube with an "impaction filter" that captured aerosols. In the laboratory, the researchers analyzed the filter's content using liquid chromatography with tandem mass spectrometry to measure THC and other cannabis compounds' concentrations. It's important to note that the study involved only 18 participants, meaning the results do not carry statistical weight but emphasize the necessity for further investigation.

Implications and Future Research: While the initial findings were inconclusive, with similar THC levels detected in pre- and post-use breath samples, the study highlighted the need for continued research. The researchers expected to observe higher THC concentrations in breath samples collected an hour after cannabis use. Still, the results did not consistently indicate recent use based solely on breath THC concentration.

To address these limitations and strengthen the findings, the research team secured a $1.5 million grant from the Department of Justice's National Institute of Justice (NIJ) to conduct a more extensive study. This upcoming research will involve a larger sample size, with at least 40 participants providing over a thousand breath samples, offering a more robust statistical analysis. 

“A lot more research is needed to show that a cannabis breathalyzer can produce useful results,” said NIST materials research engineer and co-author Kavita Jeerage. “A breathalyzer test can have a huge impact on a person’s life, so people should have confidence that the results are accurate.”

Continued advancements and funding from the NIJ would bring researchers closer to achieving an accurate and trustworthy cannabis breathalyzer, which would be a valuable tool for law enforcement and society in combating impaired driving and promoting safer roads.

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Photo: Courtesy Of Maxwell Ridgeway On Unsplash