Cannabis use during work raises workplace injury odds, research shows

In a study featured in the Canadian Journal of Public Health, the Institute for Work & Health (IWH) has shed light on the association between cannabis use and work injury risk. By distinguishing between on-the-job cannabis consumption and off-duty use, researchers found a significant difference in injury risks. 

The study's results show that workers who reported using cannabis during or before work were twice as likely to experience workplace injuries compared to their non-cannabis-using counterparts. The study also found that there was no increased injury risk for those who only used cannabis outside of work hours. 

“Our study findings demonstrate that it’s important to consider when cannabis use is taking place,” said Dr. Nancy Carnide, IWH Scientist and the lead scientist of the study.  

“Rather than considering any cannabis use as an occupational safety risk, I think employers may need to reframe their approach and focus on use that is likely to lead to impairment at work.” 

During the research project that began in June 2018, before non-medical cannabis legalization in October 2018, the IWH investigated changes in workers' cannabis habits and perceptions following legalization. Over three survey waves conducted between summer 2018 and summer 2020, 1,715 workers participated in the study. 

“Employers’ concerns about workplace impairment associated with cannabis use shouldn’t be minimized,” Carnide said.  

“Workers should be educated about the workplace safety risks of using cannabis before or during work hours, which we clearly observed.” 

“However, zero-tolerance workplace policies that prohibit workers from using cannabis entirely are likely too broad. Workplaces could instead consider incorporating minimum wait periods before a work shift when cannabis consumption is not allowed,” she said. 

The IWH is a non-profit research institute dedicated to safeguarding and enhancing the wellbeing of the workforce. Its mission is to offer valuable and applicable insights to policymakers, workers, employers, clinicians, as well as health, safety, and disability management experts, focusing on preventing work-related injuries and disabilities.