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It’s a new world for Australia’s workforce as cannabis medications are being increasingly prescribed by medical practitioners across Australia for a number of different indications, potential reducing or replacing a lot of other drugs like benzodiazepines and opioids.

There are a lot of unknowns when it comes to drug testing, impairment and what that means while working or driving. The current system, unfortunately, puts a lot of uneducated patients at risk for heavy fines, losing their license, job or having to defend themselves in court for their medical use of cannabis products.

The Therapeutic Goods Administration (TGA) and State Health Departments require physicians to consent their patients to not drive or perform safety sensitive tasks while they are taking medicines containing THC (delta-9 tetrahydrocannbidiol) – but what about CBD (Cannabidiol)? And is it safe to drive or work while taking THC or CBD medications?

First, let’s look at THC, the cannabinoid that can cause impairment.

A study was done by The Lambert Institute here in Australia, which was published in the journal of Journal of Psychopharmacology, found the THC-dominant and THC/CBD equivalent cannabis medications ingested by trial participants led to greater lane-weaving and leaving large gaps in between other cars.

And this one from Canada, where people using a driving simulator in the THC group showed signs of impairment, centering the car poorly in its lane and driving inappropriately slowly.

However, after 24 and 48 hours of smoking different levels of cannabis, the THC group in the Canadian study showed no signs of impairment, though they still tested positive for THC.

In Australia, it’s illegal to drive with any amount of THC in your system – that means that the roadside tests which are used (saliva swabs, blood, and urine tests) are not testing for impairment, but simply the presence of THC.

What if a THC medication is taken at nighttime, and someone drives or works the next day? Will THC show up in a drug test?

Although the current saliva test used by Australian police is a very imperfect one for detecting THC (read another study by the Lambert Institute published in the journal Drug Testing and Analysis) it’s still possible, and technically, you’re breaking the law.

The Study showed false negative rates were 9 percent and 16 percent for the two devices used in but they also sometimes gave a positive result when saliva THC concentrations were very low or negligible (false positive rate of 5 percent and 10 percent).

That said, if you’re using THC products, you may pass a saliva swab, but THC is definitely going to show up in your urine or blood and can potentially impact your insurance policy if an accident were to occur.

What we know is that THC is lipophilic (fat-loving) which means it can store in your fat cells – sometimes up to a month later depending on frequency and levels of use, which could lead to the potential for a failed drug test weeks after your last dose.

This puts a lot of patients in a tough spot – if THC medications are the best for your condition, do you forgoe THC mediations altogether (and use other pharmaceutical drugs, which simply have the warning “do not drive if feeling impaired”) or give up driving ?

Alternatively, some patients can achieve the same results with CBD medications depending on their condition, but this is often in much larger amounts which can mean more expensive treatment.

But what about CBD medications?

In roadside and workplace drug tests, police and employers aren’t looking for CBD, as CBD is non-intoxicating and is not known to effect cognitive abilities like motor skills or judgement.

What we do know, is that a lot of medicines in Australia that are CBD dominant can sometimes have THC present, sometimes up to 2mg/ml which can cause impairment in some patients depending on dose.

Now, full-spectrum and broad-spectrum CBD only products can still contain trace or measurable amounts of THC.  

Over a period of time, THC can accumulate in the body even in trace amounts, and store in the fat cells. The half-life for THC/CBD can be at least 4+ days, and it may take up to 5 days for 80-90% of the total dose to be excreted.

That means, depending on the amount of THC in your CBD product and the amount of CBD you’re taking, the residual THC amounts could put you into the danger zone.

So, will I fail a drug test for CBD? Possibly.

Again, you won’t fail a drug test for CBD, but you could potentially fail a drug test for any residual THC in that CBD product.

Would it show up in a salvia swab on a roadside test? Most likely not.

That said, most employers do urine tests to test for THC, and an employee would fail a drug test if their urine tests positive for any more than a trace amount of the THC metabolite (THC-COOH), usually at 40-50 billionths of a gram per milliliter of urine (40-50ng/ml). On top of this, a lot of old technology is still being used (gas chromatography) which is known to show false positives.

How long do trace amounts of THC take to leave my system?

There are a lot of factors that lead to this, including how much you took, method of administration (inhalation versus oral) how long you’ve been taking the product, your metabolism, and other factors like hydration levels.

You could hypothetically take a CBD isolate or CBD only full-spectrum oil for months, at low amounts (50 mg/day), and never fail a urine screen for THC-COOH. It’s not clear how much CBD oil is needed—or for how long—to end up with more than 40-50 ng/ml of THC-COOH in your urine. But certainly, if you’re taking large amounts of these CBD products (we are talking hundreds of milligrams daily), you could theoretically test positive for THC.

What can I do to protect myself?

This information is not meant to scare you from taking cannabis medications, but instead be well-informed so you can make an educated decision and if it is right for you.

First, see if your workplace has a drug and alcohol policy. What do they test for? How do they test for THC? What levels are deemed inappropriate?

Before starting your medication, disclose to your employer you wish to use it. Most workplaces want to see you succeed, and if the medication will help your quality of life at home and productivity at work, they might get on board.

Secondly, if using CBD mediations with trace amounts of THC, disclose this on roadside tests prior to any swab test.  It’s best to disclose this upfront as a medical patient, but remember – this is NOT a get out of jail free card. If you test positive for THC, you will most likely lose your license, receive a fine, or receive criminal charges for driving under the influence.

And finally, if you have to drive or perform safety sensitive tasks, regardless of when your last dose was, always ensure that you feel alert and able to do so, otherwise, wait until you feel capable to drive or find other forms of transportation.

To close, it’s imperative to find better solutions for drug testing for medical cannabis than the current ones in line with other countries. Professor McGregor comments, “We should instead be focusing on developing novel methods for detecting drivers who are 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,” 

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