A Justice Department-funded study by Emanuele Alves at Virginia Commonwealth University (VCU) has produced proof-of-concept for a portable, asthma-inhaler-shaped device that detects delta-9 THC in breath without secondary lab analysis.
The device uses 3-D printed cartridges with a “Fast Blue” dye and gelatin system to detect delta-9 THC, CBD, and CBN at 10–100 nanograms across multiple matrix systems. Color-space modeling produces two clusters distinguishing delta-9 THC and CBN from CBD by hue; a positive test produces a dark red color. Its three components are a mouthpiece, a cartridge where THC particles “collide and react,” and a detection zone.
The DOJ posted findings on the Office of Justice Programs’ National Criminal Justice Reference Service website last month; the results don’t necessarily reflect official agency policy. A patent application has been filed with the U.S. Patent and Trademark Office (USPTO).
The study arrives amid ongoing scientific doubt about THC impairment testing. A 2023 federally funded report by NIST and University of Colorado Boulder researchers concluded that evidence does not support breath THC as a reliable indicator of recent cannabis use. A DOJ researcher named Scott questioned in 2024 whether blood THC levels reliably indicate impairment, noting that chronic and infrequent users show significantly different concentrations at equivalent impairment levels, and challenged “per se” THC limits enacted in some states. The U.S. National Highway Traffic Safety Administration (NHTSA) concluded that “unlike the research consensus that establishes a clear correlation between [blood alcohol content] and crash risk, drug concentration in blood does not correlate to driving impairment.” A 2019 study found drivers at the legal THC limit of two to five nanograms per milliliter were not statistically more likely to cause accidents.
Congressional hearings have featured the trucking industry calling for hair-follicle testing, the Governors Highway Safety Association stressing roadside drug testing, and the Truckload Carriers Association warning that marijuana rescheduling could hamper zero-tolerance driver policies—concerns the transportation sector also raised with Congress in January. The Supreme Court last year ruled for a trucker fired over a positive THC test he attributed to a hemp-derived CBD product. A 2024 federally funded study identified two methods for detecting recent THC use with 96% accuracy; the National Institute of Standards and Technology (NIST) also planned a workshop on THC breathalyzer development. A Substance Abuse and Mental Health Services Administration (SAMHSA) official recently downplayed concerns that saliva-based testing would allow cannabis-using drivers to avoid detection.
