UNBC cannabis researcher Dr. Russ Callaghan. (UNBC photo)

UNBC cannabis researcher Dr. Russ Callaghan. (UNBC photo)

UNBC study: 10 per cent of users consume 66 per cent of cannabis

Lead researcher says results could be important in creating harm reduction policy

One year after the legalization of recreational cannabis, a University of Northern British Columbia (UNBC) researcher has found the top 10 per cent of cannabis users consumed approximately two-thirds of all the cannabis used in Canada in 2018.

Dr. Russ Callahan of the UNBC Northern Medical Program led a team from UNBC, the University of British Columbia (UBC), the Centre for Addiction and Mental Health (CAMH), and the Canadian Institute for Substance Use Research at the University of Victoria that analyzed data from the 2018 National Cannabis Survey.

The study also indicates that young males (15-34 years old) are disproportionately represented in the heaviest using subgroup and that males, in general, use more than females (60 per cent versus 40 per cent).

“This is the first study to identify this pattern, and it may be important for public-health strategies in designing interventions to reduce cannabis-related harms,” Callaghan said. “The findings are similar to those in the alcohol field, where we have found that a small subgroup of drinkers usually consumes the majority of alcohol in the population.”

Alcohol-related harm research, however, indicates it is not the heaviest using subgroup that creates the majority of the problems associated with alcohol.

“There is some evidence that most of the alcohol-related harms in societies are not found in the group of heaviest-drinking individuals, but rather in the much more numerous low-to-moderate-drinking groups,” states a UNBC press release. “This finding frequently is used to guide interventions designed to reduce overall population-level harms by focusing on interventions for the entire population rather than on strategies designed for the heaviest-using subgroups.”

It is not clear if the same holds true for cannabis use.

“At this time, we don’t know if the same pattern exists in relation to cannabis as it does for alcohol,”Callaghan said.

But he plans to find out.

“Future studies related to this project will further investigate the characteristics of the heaviest-using cannabis user group, as well as assessing how cannabis-related harms are distributed in Canadian society across individuals using different quantities of cannabis.”

Callaghan is currently engaged in another study that may shed some light on one of the societal harms of cannabis use and its distribution among users.

Callaghan and collaborators from Dalhousie University in Nova Scotia and the University of Victoria are gathering and examining data from hospital emergency departments across the country on injuries related to cannabis-impaired driving.

“I was interested in how cannabis legalization might have an impact on cannabis-impaired driving, because cannabis use is quite prevalent among young people,” Callaghan said at the beginning of the project in June. “About a third of all young people have used cannabis in the last 90 days and we know that motor vehicle collision injuries are extremely high in that particular age group.

“It is essential for the public and policymakers to understand the potential problems and benefits of cannabis legalization, and this study will provide important evidence regarding a major area of harm to youth and young adults in our society.”

He expects to publish the results by the end of this year or early next year.