Cannabis - Medically Authorized

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What is cannabis?

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Cannabis (also called marijuana, marihuana, weed, pot, grass, flower, and many other terms) is a tobacco-like greenish or brownish material consisting of the dried flowering, fruiting tops and leaves of the female cannabis (hemp) plant, Cannabis sativa.

Cannabis contains hundreds of different chemicals. Plants used for medical and recreational purposes have been selectively bred to contain greater concentrations of plant chemicals called phytocannabinoids. Two significant phytocannabinoids are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). Cannabis products may contain THC, CBD, or both in various concentrations.

Processed cannabis products and formats include dried flower (loose or rolled), vape cartridges, oils, capsules, tinctures, concentrates (hash, kief, budder, live resin, wax, shatter), topical creams, lotions, and food and beverages containing cannabis extracts (e.g., gummies, cookies, chocolate, tea, soft drinks, etc.).

Industrial hemp plants are cultivated to yield an abundance of fibre, seeds, oil, and other non-drug products which must not contain more than 0.3% THC.

What, in general, are the health effects of using cannabis?

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When cannabis is inhaled  by smoking or vaping the chemicals in the plant pass from the lungs into the blood vessels, which carry them to receptors throughout the body, primarily in the nervous system and brain. Effects may be immediate and can last up to 24 hours  . When cannabis is ingested, effects may be delayed for 30 minutes to 2 hours, depending on factors such as weight, metabolism, sex, and whether the cannabis is eaten on an empty stomach.

Regardless of the method, THC causes both psychoactive (affects brain function) and physical effects that can result in impairment. Common psychoactive and physical effects include euphoria and relaxation, drowsiness, changes in perception, time distortion, deficits in attention span and memory, increased appetite, dry mouth and eyes, cough (if smoked), momentary body tremors, and impaired motor functioning.

CBD also affects the brain and body; however, it does not cause impairment. This difference is an important distinction to be aware of when discussing safe cannabis use with workers.

As Health Canada states “Using cannabis or any cannabis product can impair your concentration, your ability to think and make decisions, and your reaction time and coordination. This can affect your motor skills, including your ability to drive. It can also increase anxiety and cause panic attacks, and in some cases cause paranoia and hallucinations.”

Users can have varying sensitivity to the effects of cannabis depending on their:

  • Age
  • Pre-existing medical conditions
  • Experience with cannabis
  • Frequency of cannabis use
  • Use of other drugs and alcohol (which can increase intoxication)

The effects of a particular cannabis strain may vary depending on:

  • The concentration of THC or CBD in the cannabis product
  • The source plant’s genetic lineage (sativa, indica, or hybrid)
  • The presence of terpenes (caryophyllene, humulene, limonene, linalool, myrcene, and pinene) which also produce various flower aromas, flavours, and colours.

How is cannabis regulated?

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In Canada, cannabis is federally regulated under the following legislation:

These laws can be viewed on the Justice Canada website.

The production, sale, and use of cannabis was legalized in 2018. Cannabis may be acquired with or without medical authorization from a health care provider.  Legal sources include buying directly from a federally licenced seller, from a provincial or territorial authorized retail outlet or online platform, or by registering with Health Canada to produce (grow) a personal supply.

Each Canadian province and territory has additional cannabis legislation. It is recommended that employers and employees review the legal requirements for their jurisdiction.

What are issues an employer should consider if cannabis is used with medical authorization?

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As with the side effects from any medically authorized, prescribed, or over-the-counter medication, employers should consider if there is a risk to the individual's safety or the safety of others. For example, while under the influence of the medication:

  • Does the person have the ability to perform the job or task safely (e.g., driving, operating machinery, use of sharp objects)?
  • Is there an impact on cognitive ability or judgement?
  • Are there other side effects of the medical condition or the treatment that need to be considered?

Because users can have varying sensitivity, each individual should be assessed on a case-by-case basis.

What should employees and employers do?

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While it is not appropriate for the employer to ask for specific medical findings and diagnoses from the employee or their health professional, employees may wish to consider informing their employer if a medical procedure or treatment may impact their ability to perform their job safely. If the organization has a substance use/abuse policy, it may be necessary to disclose the use of cannabis for medically authorized purposes.

Employers should review any workplace policies involving drug and alcohol use, in consultation with the health and safety committee and unions, as appropriate. The focus of the policy should be on “impairment” or “under the influence”, and the ability to do the work safely. Policies should be inclusive and consider any drug or substance that is medically authorized, or otherwise legal to purchase and use.

Note, however, that the use medically authorized cannabis does not entitle an employee to be impaired at work, nor allow that employee to endanger their own safety or the safety of others.

Do employers have a duty to accommodate?

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Yes. Employees can ask for accommodations due to their medical condition. For workplaces, the duty to accommodate is required by federal and provincial human rights legislation, and this right includes those who may use medical cannabis as part of their treatment for a condition. Employers have this duty to accommodate, up to the point of “undue hardship”.

The employee should be evaluated using “fit to work” procedures where the purpose is to determine if medically the employee can perform the job or task under the working conditions. Please see the “Fit to Work” OSH Answers document for more information.

Typically, the employee will visit a medical professional who will determine if the person is able to do that particular job. The employer may provide information to the medical professional about the duties performed by the work to assist in this evaluation, such as a job demands analysis of the worker’s tasks. The medical professional may consider physical or mental abilities, sensory acuity, level of skill, functional limitations, etc. The medical professional will typically only report one of three conditions back to the employer:

  • fit,
  • unfit, or
  • fit subject to work modifications.

Employers are provided with the information needed to determine appropriate work, and can confirm the nature and duration of the work restrictions with the medical professional.

  • Fact sheet last revised: 2022-09-14