At-work cannabis use linked to work factors, including some not expected: IWH study

Work characteristics linked to on-the-job consumption include lower job visibility, less chance of detection but also safety-sensitive or supervisory roles

Published: February 25, 2021

In a study that found one in 12 workers used cannabis during or just before a work shift, researchers took a close look at the factors linked to workplace consumption. They found all were related to job characteristics and workplace environments—some in ways the researchers expected (e.g. the factors made cannabis use less likely to be detected) and others in ways they did not.

The study was conducted by the Institute for Work & Health (IWH) in the months before recreational cannabis was legalized in Canada. It examined the factors linked to cannabis use and, in particular, cannabis use at work (defined in the study as using cannabis within two hours before or during a work shift).

Whether they used cannabis at work or not, workers who used cannabis in the past year (compared to those who did not) tended to be younger and male. They also had lower incomes and less education, and were more likely to smoke cigarettes and drink alcohol more frequently.

Among these workers who used cannabis in the past year, what set apart those who used cannabis at work from those who did not were work-related factors. That is, the differences between the two groups were related to the types of work people did and the work environments they worked in.

Specifically, people who used cannabis during or just before a shift were more likely to work:

  • in jobs that were away from other people;
  • in environments with fewer on-site smoking restrictions;
  • with supervisors perceived to be less skilled at identifying workers using drugs or alcohol at work;
  • in firms that had a drug testing program;
  • in safety-sensitive jobs; or
  • in supervisory roles.

Many of these findings are consistent with prior theories on the workplace factors that discourage workplace substance use. Formal workplace social controls such as smoking restrictions, as well as informal controls such as greater job visibility and supervisor ability to detect use, have been found in earlier studies to be associated with a decreased use of alcohol and illicit drugs in the workplace, says IWH Associate Scientist Dr. Nancy Carnide, who led the study. Our findings suggest that workplace cannabis use is more likely in workplaces that lack the type of controls that increase the chances of detection.

Carnide notes, however, that the results aren’t entirely consistent. For example, the study also asked workers how often they were in contact with their supervisor during a workday, how willing their supervisors were to address workers’ on-the-job alcohol and drug use once detected, and whether their employer had a formal cannabis use policy. No statistically significant associations were found between these factors (all potentially related to likelihood of detection) and cannabis use at work.

Most surprising were the findings that workers were more likely to use cannabis at or just before work when they were in supervisory roles, safety-sensitive jobs or workplaces with a drug testing program, says Carnide.

Carnide has a potential explanation for the finding about drug testing programs: their presence may simply reflect the very reason a workplace may want such a program. It may be the case that companies with drug testing programs were those that already knew they had a substance use issue in their workplace and wanted to address it, she says.

Less readily explained is the link between cannabis use at work and holding a supervisory role. This is not a common finding in the literature, Carnide says. Could it be that people in supervisory roles feel their use will likely go undetected? Could it be a way of coping with the stress and work demands involved in their job?

Similarly, the association between workplace use and safety-sensitive jobs is also hard to explain, although it, too, may reflect workers coping with stress and pain. These jobs are often physically demanding, she points out. These are potential reasons, but they’re all speculative at this point, Carnide says.

Overall, the body of research on cannabis use at work is still new, and longitudinal research is needed. Much of the literature in the past has looked at alcohol use and, more generally, illicit drug use, says Carnide. We need to unpack a lot of nuance with regards to why people use cannabis at work and what work factors promote and deter problematic workplace use.

The study, published in January 2021 in the journal Drug and Alcohol Dependence (DOI:10.1016/j.drugalcdep.2020.108386), was based on a study of about 2,000 Canadian workers, conducted in June 2018. Most of the participants were recruited from a pre-existing panel of 100,000 households held by EKOS Research Associates. A small sample was also recruited via random dialing.

Although the overall research project is set up to be a longitudinal or follow-up study, findings shared in this paper are based on a cross-sectional or “moment in time” analysis. In addition to this baseline survey, two follow-up surveys have been conducted. The first follow-up survey, which took place in the summer of 2019, found more people used cannabis after legalization, but the percentage of people who used at work did not increase.