The traffic police may soon have a new kind of breathalyzer to use on you
Weed was becoming legal across the US faster than traffic cops could keep up. With no analogue to the alcohol breathalyzer available, police have had to either legally guess whether a suspended driver was high. That may soon change, as a team of researchers at Virginia Commonwealth University has developed a prototype THC breathalyzer test.
The 3D-printed device could eventually give police a quick waypoint to detect whether a driver has recently used marijuana. The team, led by forensic pathologist Emanuele Alves, designed a device that works a bit like an inhaler. A driver exhales into a mouthpiece, triggering a chemical reaction inside a cartridge. The compound in marijuana that is responsible for getting high is delta-9 THC. If present, the mixture in the cartridge will turn dark red, indicating that the driver at least has marijuana in their system.
Currently, testing for marijuana requires laboratory analysis that can take days. This device can deliver results within minutes. It is also sensitive enough to distinguish between THC and other cannabinoids such as CBD, a non-psychoactive compound in marijuana, which would be valuable in reducing the risk of false positives.
According to the team’s research, which was published in NEWthe device can detect marijuana even in small amounts, between 10 and 100 nanograms, using a dye-based system built from fairly inexpensive materials, making the device ripe for mass production.
THC breathalyzer tests just got one step closer to reality
It is a surprise that a device like this does not already exist, since cannabis is now legal for recreational use in about half of the states in the United States, while almost all states allow it in some form. While a roadside breathalyzer for marijuana can help police make sure the roads are safer, there is still no specific consensus on what level of THC actually equals impairment.
This is where the whole discussion gets messy. Several federal studies have found that the concentration of THC in a person’s system does not reliably correlate with how impaired they are. A regular smoker may have a higher baseline and could theoretically blow a high number on a breathalyzer but would not be cognitively impaired. The occasional weed smoker, on the other hand, may be debilitated after a small hit. Other studies have shown that drivers at legal THC limits are not significantly more likely to crash.
It’s taken a while for a breathalyzer for marijuana to hit the market, but it looks like that was even the tricky part. Even if the device works as intended, states and perhaps even the federal government must first agree on something close to a consensus on the meaning of impairment as it relates to driving while high, as right now it’s a nebulous phrase with no clear definition anytime soon.
