Cannabis Window of Impairment Study Shatters Misconceptions

“Cannabis Impairment Laws Should Be About Safety, Not Arbitrary Punishment” – LPC

From the beginning, the challenge law enforcement in Canada faced was determining the cannabis window of impairment. Measuring alcohol impairment is easy. The amount of alcohol in your blood is exactly related to your level of intoxication. But THC can be detected in the bloodstream up to a month – long after the cannabis window of impairment has closed.

A new study from the University of Sydney in Australia set out to determine the exact cannabis window of impairment. The answer: up to 10 hours, depending on THC levels and how users ingest that THC.

Lead author Dr. Danielle McCartney is a researcher at the Lambert Initiative for Cannabinoid Therapeutics at the University of Sydney. “THC is known to acutely impair driving and cognitive performance,” Dr. McCartney said. “But many users are unsure how long this impairment lasts and when they can resume safety-sensitive tasks, such as driving, after cannabis consumption.

“This impairment may extend up to six or seven hours if higher doses of THC are inhaled and complex tasks, such as driving, are assessed,” she said.

Breakdown of Cannabis Window of Impairment – LPC

The new study analyzed 80 scientific studies to identify the window of impairment.

“Our analysis indicates that impairment may last up to 10 hours if high doses of THC are consumed orally,” Dr. McCartney said. “A more typical duration of impairment, however, is four hours, when lower doses of THC are consumed via smoking or vaporization and simpler tasks are undertaken.”

Those “simpler tasks” include cognitive skill tests such as reaction time, sustained attention, and working memory, Dr. McCartney said. In other words, users may show impairment for several more hours doing complex tasks such as driving.

Dr. Thomas Arkell, a co-author also from the Lambert Initiative, said cannabis use frequency also plays a part. “We found that impairment is much more predictable in occasional cannabis users than regular cannabis users. Heavy users show significant tolerance to the effects of cannabis on driving and cognitive function, while typically displaying some impairment.”

New Cannabis Window of Impairment Challenges Driving Laws – LPC

Of course, driving is one of the most common tasks that most are worried about. New findings about the cannabis window of impairment could go a long way to educating law enforcement.

“In an ideal world, we would have the equivalent of the breathalyzer,” said Eric Dumschat, legal director for Mothers Against Drunk Driving Canada (MADD).

However, that cannabis impairment test doesn’t exist. The Drager DrugTest 5000 is the only roadside test approved for cannabis impairment since cannabis was legalized in Canada.

“Our device is there to really just identify whether there’s a presence of THC,” said Einat Velichover, a business development manager at Drager. “It’s not meant to measure impairment and we never claimed that it does.”

Many police departments including in BC do not use the test. Instead, they train their officers to conduct field sobriety tests.

There is also confusion between CBD and THC among some drivers. Another Lambert Institute study found that CBD and driving do mix. CBD does not cause impairment.

“Laws should be about safety on the roads, not arbitrary punishment,” said Professor Ian McGregor. “Given that cannabis is legal in an increasing number of jurisdictions, we need an evidence-based approach to drug-driving laws.”

How Does the New Cannabis Window of Impairment Affect Workplaces? – LPC

The other area where the new cannabis window of impairment could have an effect is the workplace. Safety sensitive industries including aviation implemented a zero-tolerance policy banning cannabis use for 30 days before their next shift.

However, research found that cannabis zero-tolerance policies are not scientific.

Still, that likely won’t change employers’ minds about zero tolerance policies, especially in safety sensitive industries like aviation. Until science finds a definitive cannabis impairment test rather than a vague cannabis window of impairment, only legal challenges will likely change workplace rules.

Click here to view full story at www.sydney.edu.au

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