Careful: smoking weed at home could see your job go up in smoke

If you enjoy lighting up the green stuff after work on Friday, be on high alert. Come Monday, your job could go up in smoke.

Last year's Constitutional Court ruling legalising the personal use of dagga has encouraged more employers to test for use in the workplace and employees are now being disciplined and even fired because their recreational use outside the workplace is showing up in urine tests at work.

Traces of cannabis can be detected in the body weeks after it has been smoked.

But University of KwaZulu-Natal (UKZN) occupational medicine registrar Dr Calvin Yagan said though employers may prohibit cannabis use at work, it would be difficult to police the legal use of a drug that may or may not have an effect in the workplace.

"An employee who has smoked marijuana in the morning before coming to work may be able to function optimally at work even though technically they may be under the influence," he said.

"An employee who legally used cannabis on a Friday evening is likely to show traces of the drug if tested at work on a Monday, even though no longer under the influence and unlikely to be impaired."

A Commission for Conciliation, Mediation and Arbitration (CCMA) ruling released last month has been widely criticised for upholding the dismissal of three employees who had traces of cannabis in their urine.

The men, who worked at NCT Durban Wood Chips, admitted to smoking weed on their day off but the CCMA based its findings on the employer's zero-tolerance drug policy and agreed that they had dangerous jobs, therefore they could not be intoxicated at work. One of the men was a weighbridge clerk who received trucks on site. Another sharpened metre-long knives and the third was a log deck assistant.

"Unlike alcohol, the effects of cannabis on an employee's ability to perform his or her duties are [not] well known. I think the arbitrator may have come to the incorrect conclusion about whether the employees were actually under the influence of cannabis at work as there was no evidence of this in their behaviour, said labour law expert Jose Jorge.

"The award, however, does correctly confirm that even though the private use of cannabis has been decriminalised, employers can still discipline and dismiss employees who report for duty under the influence of cannabis where they may pose a risk to themselves and others."

He said any policy dealing with cannabis use should take into account that cannabis may be detected in the body long after it has any intoxicating effect on the employee.

Rhys Evans of AlcoSafe, which supplies test kits and helps compile anti-drug polices in the workplace, said there was an increase in confusion around policies.

"More employers are asking for assistance with this because there isn't really anything stipulated in the judgment on dagga use and the effect it would have on a person after they have used it in their private space."

Anivesh Singh, whose firm, Micromega Publications, provides occupational health and safety materials to companies, said his company had partnered with UKZN to convene a conference in Durban in August.