Detecting marijuana by way of a road-side test seems an obvious enough measure as the legalization movement gathers momentum, but an effective technology is yet to really be established. Current approaches relying on blood and urine samples are unable to distinguish between somebody driving under the influence, and somebody that has simply used the drug sometime in the last month. But one US company now claims to have developed a breathalyzer system that can measure levels of THC in one's breath to determine how much a road user is impaired when behind the wheel.

The journey toward an effective road-side breath test for marijuana has been a slow-going, with a number of private companies and research groups making gradual but important progress. These have included teams from the University of Akron and Washington State University who are working on small devices that through breath and the saliva can quickly measure THC, the psychoactive ingredient of marijuana.

Canadian company Cannabix is a private firm that claims to be closer to a market-ready product, recently announcing an alpha prototype that it says can detect THC use within a two-hour window to offer on-the-spot positive or negative readings. But other than a lot of huffing and puffing, Cannabix is keeping its cards close to its chest in terms of how its technology actually works.

In claiming a major scientific breakthrough today, California's Hound Labs isn't giving away a whole lot more. But based on just one or two breaths, its proprietary technology developed with scientists from University of California, Berkely is claimed to measure THC levels to within 500 picograms (one trillionth of a gram). Through a mix of chemistry, microfluids and engineering, it says its technology is at least one million times more sensitive than that used to measure alcohol on the breath.

"What we can tell you is that our device utilizes precise chemical reactions to isolate THC and measure the actual level of THC in breath," Hound Labs' CEO Dr Mike Lynn, tells Gizmag. "After it is optimized for a hand-held device it will be very similar to current roadside alcohol breathalyzers used all over the country."

A breathalyzer that gauges the actual levels of THC, rather than producing simply a positive or negative reading, would be a great step toward an effective solution. But there is still some conjecture over exactly what level of THC represents an unacceptable impairment for drivers. In Washington, for example, five nanograms of THC per millilitre of blood is the legal limit, while other states have taken a zero tolerance approach.

Hound Labs tells us it has tested its technology in the laboratory, with clinical trials and law enforcement roadside tests to begin soon. It will be built into a hand-held breathlyzer just like those used to test for alcohol, with the device to carry a similar cost and be unveiled early in 2016.

Source: Hound Labs