Science

Roadside saliva test could detect cannabis use

Roadside saliva test could det...
The prototype reader device (center) works in conjunction with a smartphone
The prototype reader device (center) works in conjunction with a smartphone
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The prototype reader device (center) works in conjunction with a smartphone
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The prototype reader device (center) works in conjunction with a smartphone

Even though driving while high can be just as dangerous as driving drunk, there's currently still little in the way of devices that can be used for roadside cannabis-use checks. That could be about to change, though, thanks to research being conducted at the University of Texas at Dallas.

Led by Prof. Shalini Prasad, scientists at the university are developing a system that incorporates disposable test strips, and a compact portable reader device.

Each strip incorporates two electrodes, and is coated with proteins that bind only with THC, which is the psychoactive compound in cannabis. Once a person's saliva sample has been applied to a strip, that strip is placed in the reader, which runs an electrical current through it.

Because the proteins exhibit different qualities when bound with THC, the current increases in accordance with how much of the compound is present in the sample. By measuring that increase, the reader is therefore able to calculate THC levels in the bloodstream, which closely correlate with those in the saliva.

The testing procedure can reportedly be performed onsite in under five minutes, and is capable of measuring THC levels ranging from 100 picograms per milliliter to 100 nanograms per milliliter of blood – according to Prasad, previous research suggests that a minimum of 1 to 15 nanograms/ml constitutes impairment.

"This is the first demonstration of a prototype device that can report both low and high concentrations of THC in a noninvasive, highly sensitive and specific manner," she says.

A report on the study was recently featured on the American Chemical Society's SciMeetings online presentation platform.

Source: American Chemical Society

3 comments
CarrieErbagSmith
I'd just like to point out that police forces in the UK have for some years been using a roadside device that tests for both cannabis and cocaine use. It contains a strip that is rubbed on the inside of the mouth and tongue and produces results within 8 minutes in the form of a red line for each substance. The driver is then taken to a police station, where a confirmatory blood test is conducted. Obviously it doesn't produce an accurate measurement like the one described here, but it does have the advantage of testing for the two most commonly used substances in one device, and of getting the driver off the road.
Wolf0579
This is a tool looking for a problem, developed for profit by people who have zero interest in the "Public Good". The real problem is out of control policing, fines being used as operating funds, causing departments to need to collect more and more fines, and the fact that pot DOES NOT AFFECT YOUR JUDGEMENT OR MOTOR SKILLS THE SAME WAY ALCOHOL DOES. I've driven high most of my life. If ANYTHING, being high makes one a more careful driver. The next objection is usually "hesitation from being too cautious causes accidents." If you're going to complain about hesitation causing accidents, why then, haven't you already made a priority of getting all of the overly cautious female and elderly drivers off the road? People have been way too programmed by "Authorities".
Douglas Rogers
This is a very touchy subject. It is well known that there is a minimum in the functionality vs. concentration curve for common drugs, for habitual users, but not for non users. An alcohol concentration of .08 % has proved practical for law enforcement, although it misses a lot of people. Also, many people will perform best at .02 %. Marijuana shows a similar result.