Professor Iain McGregor, Academic Director of the Lambert Initiative
The study, published in the journal Drug Testing and Analysis, found that the devices frequently failed to detect high concentrations of tetrahydro-cannabinol (THC). False negative rates were 9% and 16% for the two devices but they also sometimes gave a positive result when saliva THC concentrations were very low or negligible (false positive rate of 5% and 10%). “Detecting impairment due to Cannabis use is an important goal in promoting road safety but using saliva tests to do this appears fraught with issues”, said Professor Iain McGregor, Academic Director of the Lambert Initiative for Cannabinoid Therapeutics and senior author of the study.
The study, led by PhD student Thomas Arkell, was part of a larger study looking at the effects of vaporised Cannabis on driving. In the same way breathalysers can detect whether a driver has a blood alcohol concentration of more than 0.05%, these devices are meant to detect whether a driver has more than a certain defined amount of THC in saliva. If so, the test should come back positive. Study participants were occasional Cannabis users who consumed two different types of Cannabis or placebo Cannabis on three separate test days.
Participants had saliva tested at baseline and regular intervals after Cannabis consumption using the Securetec DrugWipe and the Draeger DrugTest 5000 – the same types of devices in use around Australia for MDT. The study tested 14 participants on two devices where the participants had vaporised placebo Cannabis, THC-dominant Cannabis, or Cannabis containing equivalent concentrations of THC and cannabidiol (CBD). In all, there were more than 300 separate tests taken. Participants were also tested for driving performance on a state-of-the-art driving simulator.
As well as using the two MDT test devices, the researchers collected separate saliva samples in order to measure exactly how much THC was in each participant’s saliva at the time of each test. This ‘confirmatory’ test used a highly accurate laboratory mass spectrometer. “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”, Mr Arkell said.
The study also found measures of accuracy, specificity and sensitivity of the two devices fell below levels recommended by EU authorities. The rationale for mobile drug testing is based on the success of the RBT program pioneered in Australia. But while there is a very clear link between alcohol intake, blood alcohol content measured in a breathalyser and intoxication, THC levels in saliva do not reliably reflect Cannabis intake or ‘intoxication’.
“We should instead be focusing on developing novel methods for detecting drivers who are actually impaired by Cannabis. The two devices used by police in MDT were never designed to measure impairment. Authorities in other jurisdictions, such as Canada, remain far more cautious in their use of such devices”, Professor McGregor said. Professor McGregor also said that when people use THC capsules or suppositories, neither of which leave traces of THC in the oral cavity, users have zero THC in their saliva, but can be heavily ‘intoxicated’.
Additionally, people tested in this study would often feel too impaired to drive two hours after vaporising Cannabis but would give a negative saliva test with the two devices. Conversely other people in the study presented with negligible levels of THC in their saliva and no driving impairment, but tested positive with the MDT devices at the detection thresholds used in the study. There is also the issue of passive smoking, Professor McGregor said that at least two overseas studies had shown people passively exposed to the Cannabis smoke of others can exhibit salivary levels of THC that would generate a positive test result.
The number of mobile ‘drug’ tests being conducted each year continues to rise, with NSW Police planning to conduct 200,000 of these tests in 2020. Study lead Mr Arkell said; “Given that these tests can cost at least $40 each, and potentially lead to serious life-changing penalties for drivers, it is imperative that these concerns around reliability and accuracy are addressed”.
Michael Balderstone, President, Australian HEMP Party and Nimbin HEMP Embassy, noted in the September 2019 Nimbin Good Times “There’s a more reliable occupancy rate in jails than hotels and the new Serco prison near Grafton, on track to open next year and employ 600 people, is sure to be a safe investment for Macquarie Bank and the others up to their neck in this sordid business … they created Cannabis cautioning to stop young people getting criminal records and lessen minor pot charges filling the courts”.
“That enabled the likes of Scomo to argue, ‘We’ve dealt with Cannabis, unless you’re a wicked drug dealer, you just get a caution, a slap on the wrist’. And now it’s a new level of political cunning we’re hearing regularly. ‘We’ve dealt with medical Cannabis, it’s legal now’. Omitting to tell us you have to be almost dead to access the legal mediweed and it’s incredibly ridiculously expensive. And all imported! And you’re not allowed to drive if you use it”.
“99% of Australian Cannabis users are unaffected by the medical Cannabis legislation, but politicians act like they’ve dealt with the issue. Reviewing the Cannabis laws has been totally swept aside by the medical debate and barely one percent of users are even helped by the changes, Meanwhile ice is on a rampage. They just don’t get it, and why would they? It’s like having teetotallers in charge of alcohol regulations”.
Michael Balderstone further told the Nimbin Good Times, why we need a Cannabis enquiry; “The Sex, now Reason, Party … came to visit and pick our brains about the Victorian government’s ‘Inquiry into the Use of Cannabis in Victoria’. Fiona (Patten) is the chair of the Legal and Social Issues Committee. The actual wording of the Terms of Reference reads …
On 30th May 2019, the Legislative Council agreed to the following motion: That this house, requires the Legal and Social Issues Committee to inquire into, consider and report, by no later than 2 March 2020, into the best means to:
• prevent young people and children from accessing and using Cannabis in Victoria;
• protect public health and public safety in relation to the use of Cannabis in Victoria;
• implement health education campaigns and programs to ensure children and young people are aware of the dangers of drug use, in particular, Cannabis use;
• prevent criminal activity relating to the illegal Cannabis trade in Victoria;
• assess the health, mental health, and social impacts of Cannabis use on people who use Cannabis, their families and carers;
• and further requires the Committee to assess models from international jurisdictions that have been successful in achieving these outcomes and consider how they may be adapted for Victoria”.
“We mostly talked about models for the future, something we’ve been dreaming about in Nimbin for decades. These are my suggestions … First up let’s acknowledge prohibiting Cannabis causes more trouble than it prevents. Pretty much everyone agrees on that, it’s just what do we do next. Or, how do we get out of the mess? So first step, stop hunting pot users and if you must, treat it as a health issue”.
“Police have better things to do and it will start reversing Aussie ‘drug’ trends which are very much about not getting busted so don’t use weed, it stinks and its bulky and you have to smoke it … the easiest bust by far. Pills and powders are a cinch to hide in comparison. Then, critically, I would legalise home growing. We can argue forever about how many plants, but it’s significant California and Colorado both allow six plants. More would be great so try for ten … ”.
“Then comes the most difficult bit of regulations, supply. I’m all for the Hemployment model. There’s 100,000 jobs out there waiting to happen and there’s also plenty of Centrelink recipients that can do a complete turnaround and become taxpayers. Fuck giving the few grow and supply licences to the same old, rich, few. In Canada … seven of the 10 licensed producers are partners with global pharma giants”.
“I’d put a ceiling on … supply licences so Big Pharma and the like are out of the picture and … let’s licence quantity. So every pound you sell is taxed as well as checked for mould and contaminants. A licence to sell a maximum of 100 lbs say at current prices, will give Aussie expertise which has been accumulating for fifty years now a chance to partake. A Dispensary licence is another matter but let’s get it out of the chemist and into the hands of people who know the subject”.
“Watching North America try countless regulatory models over more than 20 years now, we have a unique opportunity to learn from their mistakes. California has had legal medical pot since 1996 and it’s just no big deal on the entire west coast of America now. Two years ago I watched suited businessmen queue with long haired hippies to buy joints or deals at any amount of dispensaries. It was so simple and so obviously no big deal for anyone”.
“Driving also can be no big deal. Most people are safer drivers with their usual ‘drugs’ inside them. Millions taking pharmaceuticals every morning first thing; pilots use speed to make sure they stay awake. Regular Cannabis users as well as heroin or methadone users are the same as pharma users. They’re all going to be safer with their usual medications on board. Road safety has to be about impairment, and police can easily and quickly tell if someone is impaired”.
“While they’re doing the breathalyser test they can get an idea of someone’s state of mind and if they want to look further then asking a driver a few questions or to hop out of the car and walk in a straight line will take less time than waiting for the saliva stick to show up or not. ‘Drug’ test people then if you think they’re impaired and save fifty bucks on every little blue licky stick also. We can’t have machines doing everything for us, or we’ll turn into idiots”.
Background – Use of roadside saliva tests in Canada for impairment in question