TRANSCRIPT
Cannabis is the second most-used drug in Australia, after alcohol. Previously, all cannabis use was illicit but since 2016, medicinal cannabis has been accessible in Australia.
Now, hundreds of thousands of Australians access cannabis medicinally.
This has complicated drug testing, including in the workplace.
Dr Nicole Lee, Adjunct Professor at the National Drug Research Institute and Director at 360Edge, says workplace drug testing systems exist to mitigate health and safety risks.
“You see it mostly in the safety-sensitive industries, like mining, transport - those kinds of industries where, if you were affected by drugs, it would be wouldn't just be impairing your ability to work, it would be actually dangerous. They tend to use the drug testing as a kind of gateway into into the work that needs to be done.”
Drug testing can affect people outside the safety-conscious industries, through roadside drug testing.
Postdoctoral Research Associate at the Lambert Initiative for Cannabinoid Therapeutics, Dr Danielle McCartney, says Australia has a zero-tolerance approach to cannabis in this setting.
“At the roadside, Australia uses what we call zero-tolerance legislation, meaning that it's an offence to drive with THC present in blood, oral fluid, and urine at any time. You've probably seen the vans on the side of the road. So drivers are pulled over at random and subjected to an oral fluid drug test. If any THC is detected, the driver is in big trouble.”
THC is the main psychoactive compound found in cannabis.
Drug testing is pretty straightforward - in theory: you take a sample, and if it comes back positive, the person has drugs in their system.
Dr Lee says whilst a positive test is a good indicator for drugs like alcohol, it isn't as reliable for THC.
“With alcohol, if you have a breathalyser reading, you will almost certainly be impaired. So there's a there's a really good correlation between a positive breathalyser test and impairment, and the higher breathalyser test, the more impaired you are. Illicit Drug Testing is completely different because the illicit drugs tests are not as they're not as accurate, and there's quite a wide window in which you can still test positive but not be affected by drugs. Cannabis stays in the system for longer than most drugs.”
Dr McCartney says the common oral fluid test doesn't give a clear picture to what a person is experiencing.
“Oral fluid is particularly poor matrix. So THC doesn't move from blood into oral fluid, meaning that the THC actually needs to make contact with saliva in order to be present in oral fluid. So for example, someone could consume a bunch of THC in a capsule or something like that, and because it never actually makes contact with the oral fluid, you could be heavily intoxicated and test negative on an oral fluid drug test. On the other hand, people can use cannabis, they might use cannabis regularly, and THC can sort of sequester in saliva and so even though they might not have used in some time, they could return a positive test even when they are not impaired.”
Dr McCartney says other options aren't reliable either.
“Blood probably performs the best of the matrices, but still for example, if someone inhales cannabis, what you'll typically see is really high blood THC concentrations shortly following use, and if someone orally ingests THC, you'll never see anything near as high but they can still be both equally impaired. Urine, which sometimes comes up in the workplace, is not at all an indicator of impairment because cannabis hangs around in the system for a really long time, and so the metabolites can still be being excreted in small quantities by urine weeks following use. “
The Victorian Parliament is currently considering how to approach drug testing in the workplace.
Legalise Cannabis Victoria MP David Ettershank says there needs to be a more nuanced approach to cannabis testing.
“Workers should not be impaired and cause a risk to others, just as cannabis users should not be on the road if they're impaired and posing a risk to other drivers and pedestrians. And clearly in many cases, what's actually happening is that it's not about health and safety at the workplace. It's actually imposing a zero-tolerance approach to the presence of THC in people's systems, irrespective of whether or not they're impaired. And that's what we have the big issue with.”
Dr Karen Broadly is a volunteer with the Drug Advisory Council Australia.
She says the symptoms of cannabis impairment pose a risk to people's safety.
“Things like construction and aviation and driving a vehicle there are risks. Also, I would say you know, working with children, working in childcare, working with people with disabilities, maybe working in hospitality, working in front line health care, there are risks. Our view at DACA is it really should be up to employers to be able to assess the risks and have a workplace drug policy.”
Dr Broadley says although a positive test doesn't equate to impairment, it's a risk some industries can't take.
“We don't know whether that means they're impaired, we don't know when they used, but given all of the unknowns and given the risks, we need to prioritise occupational health and safety. This is not about us judging people, they have the right to go to their doctor, use whatever they need to use and be prescribed whatever they need to deal with their health issues. So that's not about this at all. It's really about the fact that some workplaces or work types, we just can't tolerate those risks.”
Police conduct roadside drug testing across Australia.
In the ACT, it's particularly challenging, as the territory government legalised personal possession of cannabis in 2020.
President of the Australian Federal Police Association, Alex Caruana, acknowledges there are limitations to the current testing regime.
“The whole reason we are drug testing people on the side of the road is to test whether they're impaired, and therefore they are posing a threat to the safety of other members on the road. However, I think the science needs to catch up, or the legislation needs to catch up there, and there needs to be a more robust way to test if some is inebriated or impaired.”
So is there a better way to test for cannabis impairment, rather than presence in the system?
Dr McCartney says there isn't a perfect test, but it's something they're working on.
“At present there is there is no perfect system, you know, the the roadside drug tests have limitations, the field sobriety tests or behavioral tests we sometimes call them also have limitations. So they're often employed in places like the US where people might be asked to perform certain tasks - stand on one leg, touch your nose, that kind of thing. What we're sort of you know, hoping to work towards is kind of a better behavioral test, I guess, using more tech, things like computerised cognitive tasks.”
Dr McCartney says a mix of cognitive and bio-marker tests may give the best result.
“So you need some kind of behavioural metric that is very consistent from one individual to the next and isn't impacted by too many other things. I wouldn't be surprised if maybe a combination of a bio-marker with a behavioural test might give us the most reliable results. So if you don't perform so well on behavioural test, they give you the oral fluid test.”
Police test for a range of substances, but not all substances, on the road.
Mr Caruana says although an officer may be able to tell someone isn't fit to drive, they sometimes can't do anything about it.
“It puts police officers in a difficult position if for instance, they pull someone over and it's evident that they're under the influence but they're not under the influence of anything that is testing positive on the side of the road, it becomes really difficult for that police officer to then say to that person, off you go, because they're clearly posing a threat to the public, but also stay and we need to do something. What's that something that we've got, that's a missing piece.”
In the meantime, there's an argument that medicinal cannabis should be treated in the same way as any other medicine.
Mr Ettershank says THC impairment is comparable to other prescription drugs.
“It should be treated the same as any other medicine. Because when you look at the table of harms or when you look at the scale of impairment, the reality is that cannabis is pretty low down. So it's perfectly fine to go to work legally, with opioids, with benzodiazepines and antidepressants, even with antihistimines, all of those things are far more impairing than THC. For all of the other drugs, we say that the relationship between the patient and the doctor is an appropriate test to ensure safety whether it's at the workplace or whether it's on the road, except for cannabis.”
Dr Broadley says to keep workplaces safe, there may be a need to test for other prescription drugs too.
“I think we probably need to think maybe rethink even some of those other drugs as well, to be honest with you. I think it's really important not to discriminate against certain people who use certain medicines.”
Dr Lee says alcohol and drug testing should only be one factor that's looked at in workplace safety.
“We suggest workplaces take a what we call a 'fitness for work' approach. So we know that alcohol and other drugs impact on people's ability to do their work, but there's a whole range of other things like fatigue, mental health problems, some medications they may be taking, stress. And workplaces don't have as much trouble understanding if someone's fatigued, that they're not effective, and maybe they might send them home or give them kind of lower duties for the day.”
