Does cannabis use negatively impact work performance? This study says yes


By Salina May

Since cannabis became legal for recreational use in Canada two years ago, and became accessible to many new users, questions have arisen about how the use of recreational cannabis affects the daily lives of Canadians, including in the workplace.

Employers spend a considerable amount of money on drug testing for employees. American research company Statistics Brain puts company spending on drug testing across the border,at approximately US$3.75 billion annually.

Now researchers have tackled the issue of cannabis use and workplace performance in a study published in May of this year, and found mixed results in the use of cannabis on workplace performance, due to differences in how and when the substance is consumed.

The study measured workplace performance of 281 employees based on five work-related outcomes rated by their direct supervisor, including task performance, citizenship behaviours, and counterproductive work behaviours. The distinguishing element of this study is that the timing of cannabis use (before, during or outside of work hours) was assessed, whereas past studies considered all cannabis use as the same regardless of when it was used.

The results of the study showed negative impacts on four of the five workplace behaviours (task performance, organization-aimed citizenship behaviours, and two forms of counterproductive work behaviours), when cannabis was consumed within two hours prior to starting work, and when it was consumed during work hours.

The study found no effect, negative or positive, on the use of cannabis before or during working hours on citizenship behaviours aimed at individuals within the organization.

The study also showed that no relationship exists between workplace performance and consuming cannabis outside of work hours, which can have important implications for workplace drug testing and policies regarding cannabis, because the effects of cannabis are “quickly induced and rapidly dissipated.”

For example, most companies that test for cannabis as part of their drug screening policies use urinalysis or other medical tests that can only detect the presence of cannabis metabolites, but not the frequency or timing of the cannabis use.

If using cannabis outside of work hours has no effect on workplace performance, but drug testing cannot determine if cannabis was used before, during or outside of work hours, the testing has limited value.

The study asserts that companies will be “hard pressed to provide legally defensible justifications for the continuation of policies prohibiting all forms of cannabis use (or time-invariant drug tests.)”

The government of Canada’s website on Impairment in the Workplace describes the use of employee drug testing as a balance of two competing objectives: preserving privacy and human rights, and ensuring public and employee safety.

The results from this study show that cannabis employee drug testing cannot, in its current usage, distinguish between on-the-job cannabis use that harms workplace performance, and off-the-job cannabis use that has no effect on workplace performance. In that context, companies may need to re-evaluate their testing procedures and policies to ensure a better balance between individual rights and employee and public safety.

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