Medical & Recreational Cannabis in the Workplace
Fit for Work?
This article is Part 2 of a 2-Part series authored by Corridor’s Subject Matter Expert on Alcohol & Drugs, Barb Butler.

Alcohol & Drug Expert
As noted in the first blog “Cannabis Use at Work” of this series, organizations in many sectors across the country have policies in place to ensure employees are fit for work and free of any negative effects of alcohol or other drug use. These policies focus on safety in the workplace and set out clear standards on alcohol and other drug use and possession, outline available prevention and assistance programs, set out procedures to investigate a possible violation of the standards including alcohol and drug testing under certain situations, and set clear consequences for a violation of the Alcohol and Drug Policy. This approach has been consistently upheld in arbitration and human rights cases over the past years.
Historically workplace policies have focused on fitness for work, setting rules around alcohol and illicit drug use and possession, plus responsible use of medications. However, with the change in accessibility of cannabis for medical purposes, and the legalization for recreational purposes, it remains the responsibility of the employer to ensure workers are not under the influence of cannabis on the job, presenting a potential safety risk. Therefore, company policies are also making it clear that the rules and prohibitions around alcohol and illicit drugs also apply to cannabis, whether it is used for medical or for recreational purposes.
Cannabis and Workplace Performance
Over the years, research (Note: The linked research was done with significantly low levels of THC, no new research has been done with the higher grade that is readily available today, purchased legally or illegally.) has shown cannabis impairs or reduces short term memory, alters sense of time, and reduces concentration, swift reactions and coordination. The weight of the evidence clearly reveals significant psychomotor impairment while the user may not even be aware of the effects. In addition, research has found more serious implications if cannabis is combined with alcohol use. As a result, many employers are prohibiting any cannabis use at a company social event where alcohol is served.
To help employers better understand the situation, the Occupational and Environmental Medical Association of Canada issued a position statement on the implications of cannabis for safety-sensitive work. They note that cannabis is the most commonly identified product in workplace testing programs in Canada, second only to alcohol. Cannabis is also the most prevalent substance identified in driving under the influence.
“OEMAC recognizes that current evidence indicates cannabis is the most commonly encountered agent in workplace drug testing in Canada, and second to alcohol, the most
prevalent substance implicated in driving under the influence.”
Occupational and Environmental Medical Association of Canada
“Position Statement on the Implications of Cannabis Use for Safety-Sensitive Work”.
The position statement further details the impairing effects relevant to employers and concludes it is not advisable to operate motor vehicles or equipment, or engage in other safety-sensitive tasks for 24 hours following cannabis consumption. The 24 hour period can be longer if impairment persists. They also identified that more research is needed on the impacts of higher grade cannabis that is readily available across the country (whether accessed legally or illegally). It is recommended that “employers update their workplace policies to address the use of cannabis and the mitigation of occupational risk”.
The most recent study led by Canadian researchers was published in January 2022 in the scientific journal Addiction. It found that cannabis use in both recreational and chronic users can lead to persistent and severe acute cognitive impairment that may continue well beyond the period of intoxication.
The challenges of cannabis use and workplace safety will persist, and employers need to be diligent in setting clear policies and enforcing them for all employees and in particular for those who do safety-sensitive work.
Workplace Alcohol and Drug Testing
Many employers who have comprehensive policies have decided to include alcohol and drug testing as one investigation tool of a possible violation. The standard practice is to conduct alcohol testing using a calibrated breath testing device, and collection of a urine sample for drug testing, which is analyzed in a certified laboratory. Employers have introduced testing in a number of circumstances including:
• Drug test as a final condition for qualification to a safety-sensitive position
• Alcohol and drug test in a reasonable cause situation, after an initial investigation where someone appears unfit, and the supervisor concludes alcohol or drug use may be a factor
• Alcohol and drug test as part of an investigation into a serious incident (as defined in the policy); reasonable cause is not required
• Testing on return to duty if employment is continued after a violation, and on an unannounced basis for a period of time set out in an individualized agreement
• Testing on return to duty after attendance in a treatment program, and on an unannounced basis for a period of time normally recommended by a Substance Abuse Professional
• Some companies have introduced a program of random alcohol and drug testing for employees in their highest risk positions.
Legal cannabis use for recreational purposes should not change the drug testing slate in employer programs. Cannabis is a mood-altering substance that can present a safety risk if someone is under the influence. However, it is recognized that THC can be stored in the fat cells and be detected in the urine for some time after consumption, unlike the other drugs tested that are water soluble and leave the body fairly quickly. As a result, under certain situations, companies have moved to confirming cannabis presence using oral fluid analyzed at the laboratory, which tightens the window of detection to confirm recent use in line with the guidance of the Occupational and Environmental Medical Association noted earlier in this report.
Conclusion
Employers have an obligation under occupational health and safety legislation to ensure all employees and contract workers are operating safely. Setting out a clear policy addressing alcohol and other drugs for employees and a separate statement of requirements for contractors is one key way to meet this obligation. Critical to this is clear communication of the rules and expectations along with providing training for supervisors so they understand their own obligations when it comes to ensuring compliance with the alcohol and drug policy for all those they supervise.