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On the same day a major Canadian oil producer and its union were in court fighting about random drug testing on the job, a new study said employees should be aware they could fail such tests due to second-hand smoke from marijuana.

A new study from the University of Calgary says THC — the active ingredient in marijuana — is detectable in the body after as little as 15 minutes of exposure, even if the person is not actively smoking it.

READ MORE: 2% of tested Toronto transit employees fail drug test in first 6 months

The study is published online in Canadian Medical Association Journal Open.

Findings suggest anyone exposed to second-hand smoke in a poorly ventilated room including a kitchen, basement, or living room with the windows closed, will test positive after 15 minutes.

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It can take between 24 and 48 hours for the THC to clear the system.

The study says that could prove problematic for workers at businesses that have a zero-tolerance drug policy.

Suncor’s base plant with upgraders in the oil sands in Fort McMurray Alta, on Monday June 13, 2017. THE CANADIAN PRESS/Jason Franson

The study comes on the same day oil company Suncor is in court in Edmonton, fighting for random drug and alcohol testing at its oil sands facility near Fort McMurray.

Suncor started randomly testing staff in safety-sensitive jobs in 2012, but the union representing many of those workers called it an infringement of privacy.

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The company is fighting an injunction granted five years ago to union Unifor local 707A, which put the proposed program on hold while it went to arbitration.

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Unifor local 707A was granted an injunction and the program was put on hold while the issue went to arbitration.

The arbitration board ruled in favour of Unifor, but that decision was later overturned by an Alberta Court of Queen’s Bench judge last year.

READ MORE: Alberta judge quashes 2014 decision that ruled against Suncor random drug tests

Unifor appealed, but the verdict was upheld this past September by the Alberta Court of Appeal — which said the matter should be heard by a fresh arbitration panel. That process is happening Thursday.

READ MORE: Court rules in favour of Suncor on random drug testing; union to keep fighting

Suncor argues the testing is necessary for workers in safety-sensitive positions at some of its sites in the Fort McMurray area. Unifor claims random testing is an infringement of workers’ privacy rights.

— With files from The Canadian Press