Cannabis Breathalyzer Accuracy Questioned in Federally Funded Study, Prompts Further Research
A federally funded study investigating the development of a breathalyzer-like device for cannabis has raised doubts about its accuracy. According to researchers from the National Institute of Standards and Technology (NIST) and the University of Colorado Boulder, the levels of THC (the psychoactive component of cannabis) in breath samples were found to be too inconsistent to reliably determine recent marijuana use. The study’s findings emphasize the need for additional research to ensure the accuracy of a potential cannabis breathalyzer.
The study, published in the Journal of Breath Research, involved 18 participants from Colorado who smoked marijuana with a consistent THC concentration of around 25 percent. Breath and blood samples were collected before and after smoking, and laboratory analysis was conducted to measure THC levels. The researchers used a comfortable white van parked conveniently outside participants’ homes as the collection site.
Out of the 14 participants who provided both pre- and post-use breath samples, only eight showed the expected increase in THC levels after cannabis use. The remaining results were inconsistent, with some post-use samples showing no THC detection or even lower levels compared to baseline samples. This inconsistency in breath aerosol collection poses an ongoing challenge for researchers aiming to develop a reliable cannabis breathalyzer.
In contrast, blood measurements of THC concentrations in plasma proved to be a more dependable indicator of recent cannabis use. Even when THC concentrations in blood indicated compliance with the protocol and a substantial increase immediately after use, THC in breath one hour post-use did not consistently exceed baseline levels.
Tara Lovestead, a NIST supervisory chemical engineer and co-author of the study, expressed surprise at the similar range of THC concentrations in breath samples before and after marijuana use. The inability to discern recent use within the last hour based on breath THC concentration highlighted the need for a reproducible protocol for breath measurements.
While the current study focused on smoking as the method of cannabis consumption, lead author Kavita Jeerage mentioned the importance of investigating other modes of consumption such as vaping and edibles. NIST is actively conducting separate research that encompasses these different forms of cannabis use, along with the utilization of alternative breath sampling devices. This expanded research aims to gain a comprehensive understanding of how THC and other cannabis compounds enter and manifest in breath.
The development of field sobriety tests for THC has gained attention as more states have legalized cannabis. However, no cannabis field sobriety test, including breathalyzer-inspired devices, has achieved widespread adoption thus far. Policymakers consider such tests crucial in combating impaired driving, and the need for accurate drug-impaired driving identification and law enforcement enforcement remains a priority.
NIST, part of the U.S. Department of Commerce, recognizes the significance of studying how the concentration of cannabis compounds on a person’s breath changes after marijuana use. The agency’s current study, funded by a grant from the Department of Justice’s National Institute of Justice, has received an additional $1.5 million to continue and expand its research. The upcoming phase will involve a larger sample size of 40 or more participants and over a thousand breath samples, providing more statistically significant results.
As the debate surrounding cannabis legalization and highway safety persists, accurately measuring cannabis concentration in a person’s system and its impact on driving ability remains challenging. Studies yield conflicting results, with some suggesting a potential increase in road deaths following adult-use legalization, while others indicate a decrease in impaired driving incidents based on self-reported surveys. The relationship between THC concentrations in blood and impairment remains uncertain, further underscoring the need for continued research in this field.
In conclusion, the federally funded study casts doubt on the accuracy of a cannabis breathalyzer, emphasizing the need for further research to ensure its reliability. Detecting THC in breath as a single measurement does not consistently indicate recent cannabis use, as revealed by the study’s findings. As more states legalize cannabis, the development of accurate field sobriety tests and the enforcement of laws pertaining to drug-impaired driving remain important considerations for policymakers.
