A positive cannabis test simply shows that the substance was consumed or that its metabolites remain inside the system.
Workplace drug tests can fail to prove current impairment because leftover metabolites stay in the body long after any actual effects wear off.
South Africa legalized private adult use, cultivation, and possession when President Cyril Ramaphosa signed the Cannabis for Private Purposes Act into law in 2024. That legislative shift created tricky compliance challenges for employers responsible for maintaining safety in jobs where impaired judgement, slower reactions or poor coordination could have serious consequences.
Dr. Robin George, Senior Occupational Medicine Practitioner at Workforce Healthcare, explained that a positive result does not mean an employee is currently unable to do their job safely. “It does not tell you that the person is currently intoxicated or impaired,” George said.
Unlike alcohol, cannabis metabolites remain detectable in the body for days or even weeks after use. Employers can get into difficulty if they treat a positive test as automatic proof of impairment.
George said that other legal substances can create workplace hazards without triggering the same testing protocols. “An employee could, for instance, take a Valium or cough mixture, both legal substances, and be at work in no condition to operate machinery or properly complete their work,” he said.
Cannabis can affect concentration, judgement, reaction time, balance, and coordination. Such hazards demand careful attention from individuals driving vehicles, handling industrial equipment, laboring at elevated heights, or undertaking any other high-stakes duties.
Companies need policies that define what it means to be fit for duty rather than relying on a simple ‘positive test equals misconduct’ approach. George recommended that organizations engage specialists to assist in drafting guidelines and steering clear of the complex pitfalls associated with managing intoxicants on the job.
Supervisors should also be able to recognise and objectively document possible signs of impairment. “Supervisors should also be able to recognise and objectively document possible signs of impairment, such as slowed responses, poor coordination, confusion, reduced alertness or difficulty following instructions,” George said.
When there is concern, a fitness-for-duty assessment by a health professional may be appropriate. Workplace substance policies need to consider the nature of the job, the potential safety risks and evidence of actual impairment.
Employers also have a responsibility to remember that problematic cannabis use can be a health issue. A comprehensive and responsible substance policy can incorporate supportive measures like employee assistance, counseling, rehabilitation, and other wellness programs when suitable.
“Employers have to balance two important responsibilities: protecting the health and safety of everyone in the workplace while also dealing fairly with employees,” said Dr. Robin George, Senior Occupational Medicine Practitioner at Workforce Healthcare.
