4 things employers need to know about marijuana

December 22, 2021

Marijuana smoke

Make no mistake: recreational use of marijuana comes with significant risks for your workplace. This was the thrust of a recent presentation by Dr. Bruce Demers, Medical Director and Chief Medical Review Officer, CannAmm Occupational Testing Services. "It increases the risk of accidents and injuries, period," he said.

In a session at WSPS' annual Partners in Prevention Health & Safety Conference & Trade Show, Dr. Demers drove home this point with a detailed review of how marijuana affects us. Here are highlights from his session.

Marijuana affects critical functions of our brain. Dr. Demers identified eight areas of the brain affected by marijuana use. Among them, we rely on these four to work safely:
- basal ganglia - involved in motor control and planning, as well as initiating and terminating action,
- cerebellum - centre for motor control and coordination,
- hippocampus - important for memory and learning facts, sequences and places,
- neocortex - responsible for higher cognitive functions and integrating sensory information.
The effects can linger. For instance, people who use cannabis regularly may have trouble with certain driving skills for weeks after their last use. This is because THC (the active ingredient in marijuana) can affect our coordination, reaction time, ability to pay attention, decision-making abilities, and ability to judge distances.^[1]
Marijuana may have a significant impact on mental health. Health Canada notes that for some people marijuana use increases the risk of developing mental illnesses such as psychosis or schizophrenia, especially among those who use cannabis frequently (daily or almost every day), or have a personal or family history of psychosis and/or schizophrenia. Frequent cannabis use has also been associated with a greater risk of suicide, depression and anxiety disorders.^[2]
Expect recreational use of marijuana to increase significantly after it becomes legal. U.S. workplace testing results show a striking increase in the number of workers who tested positive in states that have legalized recreational use since 2016: Nevada (43%), Massachusetts (14%) and California (11%). These states also saw significant increases in marijuana positivity among workers in federally-mandated safety-sensitive positions: Nevada (39%), California (20%), and Massachusetts (11%).^[3]