A new study out of Sydney University has found the roadside drug testing devices used by police in Australia could be unreliable when testing for cannabis and may not be appropriate as a measure to stop people driving while intoxicated.
It’s bad news for NSW Police: the organisation plans to conduct at least 200,000 mobile drug tests by 2020. Of course, it’s also just as likely that they will all just continue about their business, using the routine answer that cannabis is illegal, and any trace of it in your system means Very Bad Things.
“What we found was that these test results often came back positive when they should have been negative, or conversely that they came back negative when they should have actually been positive,” said Thomas Arkell, who is a PhD student at the University of Sydney.
Arkell’s study found that the devices used by police (the Securetec DrugWipe and the Draeger DrugTest 5000) had false negative rates of nine percent and 16 percent. On some occasions, they also returned positive results when THC concentrations in saliva were very low or negligible.
In total, 14 people were tested more than 300 times during the study, conducted at four different timepoints and using a placebo cannabis, a THC-dominant cannabis, and cannabis containing equal amounts of THC and CBD. Participants were also asked to try out their driving performance with a driving simulator, which sounds cool as hell.
The findings were part of Arkell’s larger study looking into the effects of cannabis on driving run out of the University of Sydney’s Lambert Initiative for Cannabinoid Therapeutics.
The academic director of the Lambert Initiative, professor Iain Mcgregor, said that using saliva tests to detect impairment due to cannabis use appears to be “fraught with issues.”
“We should instead be focusing on developing novel methods for detecting drivers who are actually impaired by cannabis,” he said.
“The two devices used by police in mobile drug testing were never designed to measure impairment. Authorities in other jurisdictions, such as Canada, remain far more cautious in their use of such devices.”
The full study was published in the journal Drug Testing and Analysis. You can read it here.
