There is considerable confusion on the impact of marijuana or cannabis, in the workplace and its effect on safe work performance. Information on impairment at the workplace is scarce at best, and this is due to the complex nature of cannabis including the concentration of various cannabinoids, challenges determining dosage, personal tolerance and frequency of use. Questions around how work performance, vigilance and safety are impacted by cannabis are poorly understood, especially in safety sensitive work environments leaving many employers confused as to how to approach and manage impairment.

The simple reason for the lack of empirical data regarding cannabis impairment is that it was, until recently, illegal. As a result, most safety sensitive work environments enforced a zero-tolerance policy and thus it was not relevant to understand the potential impacts of cannabis in the workplace. Employers are now faced with new challenges around protecting their workforce from impairment while respecting human rights and privacy concerns. They have been left piecing together the facts and applying what is known, regarding the potential impact of cannabis use in their work environments.‍

What do we know about cannabis impairment and safety?

‍Cannabis consumption results in a variety of physical and cognitive effects that include euphoria, sedation, loss of coordination, anxiety, altered perception of time and space and loss of memory. The challenge is that these effects vary from person to person, strain of cannabis to strain of cannabis, and are governed by several difficult to quantify variables including environment and personality. As a result, it is difficult to quantify the exact effect it will have on our workers.

The legalization of recreational cannabis doesn’t change the way employers handle drug and alcohol testing. However, cannabis raises a particular difficulty: the lack of correlation between the amount in a person’s system and impairment. Employers should be aware of some of the main issues around their right to test, which recent legal cases have highlighted. They also need to understand the importance of updating their drug and alcohol policies to deal with the potentially greater presence of cannabis in the workplace.How long impairment lasts, is still up for debate and will evolve over time as more research is conducted on cannabis and task performance. What is known is that driving within 1 hour after smoking cannabis produced higher odds of motor vehicle accidents than driving within 2 hours.

‍Testing Methods

‍The standard methods of testing for cannabis use are based on analysis of saliva (oral fluid), urine and hair follicle analysis and blood tests. The most popular for use in the workplace tends to be saliva testing. Performed by taking a swab inside a person’s mouth, saliva testing detects shorter periods of time between use and testing and thus detects more recent use. Blood testing is considered highly invasive and few employers use it.

These testing methods measure the level of THC (tetrahydrocannabinol), the main psycho-active chemical in cannabis, in a person’s system. Some employers set the acceptable level of THC at 5 nanograms per millilitre (ng/mL); others set it at 10 ng/mL. Testing can also measure the level of CBD (cannabidiol), another, non-psychoactive compound in cannabis.  Generally, it will take at least 24 hours for an employer to get test results back from the laboratory conducting the sample analysis. The time will vary, depending on the type of test used and on the distance of the lab from the employer’s workplace. Despite its ability to measure THC levels in the body, such testing does not reliably measure impairment, as cannabis stays in the body for varying lengths of time depending on several factors, including how much cannabis is used and how frequently it’s used. So, the issue concerning what extent THC levels correlate with impairment is undetermined.

The Draeger Drug Test 5000 has been used in some European countries for several years and has just been approved for use in Canada. It allows police officers to conduct roadside saliva tests. So far, law enforcement has relied on the standard field sobriety test, during which they observe the driver’s ability to stand on one foot or walk in a straight line. With this device, the officer gives the driver a prepared test cassette and asks him or her to provide a saliva sample. The cassette with the saliva swab is then inserted into an analyzer, which produces the THC reading within a few minutes. There are however, some concerns about the device, including its reliability in very low temperatures.

‍Employer Policies

• Complex tasks in safety sensitive environments typically result in the greatest degree of job planning, preparation and training in an attempt to mitigate risk of injury or incident. Not surprisingly, complex tasks requiring multiple cognitive and motor skills are particularly sensitive to cannabis’s impairing effects and display less tolerance than other less complex tasks.
• It is thus important for employers to understand their specific work environments, associated tolerances and that the legalization of recreational cannabis did not change their right to drug test. Based on roles functions, employers generally have the right to conduct pre-employment drug testing.
• The right of the company to test and the rules governing the testing should be stated clearly in the company’s drug and alcohol policy.
• When an employee tests positive for a drug and is deemed to have an addiction or other medical problem, the employer must consider human rights legislation. An addiction is considered a disability and the company may be required to accommodate the employee.
• Testing is also accepted in post-incident situations, as part of an investigation, and where there is a reasonable suspicion of drug use.
• The employer should also state what actions, including discipline, will be taken when the test results come back and how the company will ensure worker confidentiality.
• It should also outline return-to-work requirements for workers who tested positive and cover accommodation policies for workers with an addiction.
• Additionally, the policy should tell workers how to use the workplace reporting process should they believe a co-worker may be impaired.
• The education and training the company intends to provide to workers and managers should also be outlined.
• Those employers focusing on worker education of cannabis, the design and implementation of well-developed drug policies as well as an eagerness to determine the impact of cannabis on safety, will be those that are best equipped to tackle the inevitable challenges that will arise from the legalization of cannabis in safety sensitive work environments.