The International Council on Alcohol, Drugs & Traffic Safety (ICADTS) has released a series of fact sheets about cannabis-impaired driving to help inform policymakers around the globe.

Developed in consultation with leading impaired driving researchers including Australia’s Swinburne University of Technology, the fact sheets highlight issues for policymakers to be aware of including:

  • Cannabis impairs driving, although the degree of impairment it produces varies substantially depending on the dose, the individual, and other factors.
  •  Cannabis, when consumed alone, is associated with a modest increase in crash risk at the population level according to most studies which compared the presence versus the absence of cannabis.
  • A driver testing positive for THC is insufficient to conclude driving impairment. Any impairment is dependent on not only the dose and route of administration, but also the frequency of use and whether cannabis has been consumed alone or in combination with alcohol or other substances.
  • Alcohol and cannabis produce different patterns of impairing effects.
  • The combined effect of alcohol, even in low concentrations, and cannabis is particularly dangerous for driving.
  • The length of time needed to recover from cannabis intoxication is not fixed and depends on various factors, such as biological characteristics of consumers, type of cannabis consumed, dose, and method of ingestion.

Swinburne research fellow Dr Thomas Arkell said there is very little consistency in how jurisdictions manage the issue of impaired driving and cannabis around the world.

Dr Thomas Arkell

“A priority moving forward is establishing greater uniformity in the types of tools used to assess impairment and the way in which results are recorded,” he said.

“This would allow us to pool data from different jurisdictions and better assess the impact of expanding legalisation on traffic safety. 

“It would also help accelerate learning to enable researchers to provide clearer answers to policymakers on important legislative issues.” 

Professor Luke Downey, who leads the Drugs and Driving Research Unit at Swinburne, added: “Roadside drug testing, which was first introduced in Victoria in 2004, is now routinely used in all Australian jurisdictions to deter and punish drug driving. 

“The program is expanding in most jurisdictions, with Victoria Police alone now conducting some 150,000 tests per year.

“Patients using legally prescribed medical cannabis are not exempt from these tests (which target the presence of THC in saliva) and associated legal sanctions.” 

The ICADTS work group has reached a consensus recommendation that medical cannabis consumers should not be subject to THC zero-tolerance laws that make it illegal to drive with any detectable level of THC, as is the case with some other types of impairing medications, but they should still be subject to impaired driving laws.

This approach, were it to be introduced, would treat legally prescribed medical cannabis in the same way as other medicines that can impair driving, such as benzodiazepines and opioids.

Former ICADTS president and Maastricht University Professor Jan Ramaekers said: “Unlike alcohol, the research regarding the impairing effects of THC on driving is much more complex because cannabis does not have a clear concentration-effect response.

“This means it’s difficult to conclude whether a specific THC concentration is indicative of driving impairment in an individual, making policy decisions much more complex.”

The fact sheets can be downloaded via this link.

Prior to launching Cannabiz, Martin was co-founder and CEO of Asia-Pac’s leading B2B media and marketing information brand Mumbrella, overseeing its sale to Diversified Communications in 2017. A journalist...

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