Part of Cannabis and your health
The Conference Board of Canada and The Globe and Mail are partnering to explore the relationship between career success and cannabis use. Employers and employees (both recreational and medical cannabis users, as well as non-cannabis users) are invited to participate in this study. (Employees interested in taking the survey can click on this link.; Employers interested in taking the survey can click on this link.) The data from these surveys will be aggregated and used to conduct analysis and create a report that will be presented Oct. 15, 2019 at a conference at The Globe and Mail Centre in Toronto.
Since Canada legalized recreational cannabis, many Canadians have grappled with the question of how long before work they can get high. They want accurate information about how and when they can safely use it. This is especially true for employees working in safety-sensitive workplaces, and most notably for those whose workplaces test for alcohol and drugs.
Although everyone wants a simple answer, there isn’t one for cannabis.
Cannabis is not what it used to be. Studies even 20 years ago underestimated the impairment it causes. It’s important for employees to understand that, although they may feel the effects from cannabis have passed, impairment can linger for some time.
Cannabis is a complex plant with hundreds of active ingredients. The length of time that cannabis affects an individual depends on many factors. Some elements that determine how long cannabis might affect a person are:
· quantity of the cannabis being consumed;
· concentration of tetrahydrocannabinol (THC), the psychoactive ingredient in cannabis;
· route of consumption (inhaled, ingested);
· makeup of the cannabis (the other cannabinoids, terpenoids and flavonoids that may have any impact);
· person’s history of use;
· other medications or substances being taken, as they could interact with cannabis;
· individual’s metabolism and body build.
Unlike alcohol, the effects and length of cannabis impairment are unpredictable and non-linear. Its effects vary from person to person, as does the length of time that it impairs.
The Occupation and Environmental Medical Association of Canada (OEMAC) recommends the following guideline:
“[T]he timing and duration of cannabis impairment is variable and … more research is needed in this regard. To provide practical guidance, until definitive evidence is available, it is not advisable to operate motor vehicles or equipment, or engage in other safety-sensitive tasks for 24 hours following cannabis consumption, or for longer if impairment persists.”
Some safety-sensitive workplaces have policies that prohibit workers from using cannabis for 28 days or longer before reporting for work. Others require abstinence. The reasoning behind this is likely rooted in studies that show persistent negative effects on memory, thinking and reasoning, visual perception, reaction time and manual dexterity. Heavy and prolonged cannabis use has been associated with difficulties learning and solving problems, even after 28 days of abstinence.
Over the past couple of decades, concentrations of THC have increased significantly in cannabis. From the 1960s to early 1990s, most recreational cannabis contained less than 5 per cent THC, with most ranging from 1 per cent to 3 per cent. We now see strains with concentrations of up to 90 per cent.
A recent study out of London has shown there is more high-dose cannabis (with THC over 14 per cent) available over the past number of years; cannabis tested for the study contained high levels of THC and lower levels of cannabidiol. Legal medical cannabis may contain up to 30 per cent THC, and cannabis containing 25 per cent THC or more can be purchased through the legal recreational market.
It’s important that employees – especially those working in safety-sensitive roles – recognize that the cannabis they are consuming could still cause unintended impairment, even after they no longer feel high.
Employees in safety-sensitive positions who might face alcohol and drug testing will want to be sure they are fit for duty, and should be aware of the type of testing used in their workplace. Urine testing detects THC, which remains in the urine of infrequent users for days, or for weeks in more frequent users.
When considering the question of how long before work they can use cannabis, employees should remember that impairment can last a long time, especially in the face of higher-potency cannabis. They should also think about the OEMAC recommendations and their employer’s fitness for duty policy, as well as what kind of tests they may have to take.
Just because cannabis is legal doesn’t mean it’s without risk. There are many things for employees to consider to safely use cannabis, including the type of work they do and the potential consequences of being impaired at work.
Bill Howatt is the chief of research for work force productivity at the Conference Board of Canada.
Melissa Snider-Adler is the chief medical review officer at DriverCheck Inc., a medical testing and assessment services company.