Send this page to someone via email

Millions of Canadians take risks every day in dozens of unforgiving “safety-sensitive” occupations: heavy vehicle drivers, industrial electricians, oil and gas workers, forestry workers, and many more.

And as the legalization of recreational pot nears, their employers face a thankless puzzle: liability if a stoned employee causes an accident, pushback from workers who resist random drug and alcohol tests, and the lack of a settled standard around either how much cannabis is too much, or how to measure it.

The Toronto Transit Commission, Canada’s largest transit authority, has been wrestling with the issue since last May, when it brought in random drug and alcohol testing for all of its employees. The TTC defines a THC level of over 10 nanograms per millitre of blood (ng/ml) as a failure. So far, 16 people have failed the TTC’s drug tests for THC levels of whom 13 were fired, said spokesperson Brad Ross.

Story continues below advertisement

“In 2011, we had a fatality where the bus operator hit the back of a truck,” Ross says. “A woman on board the bus was killed. The operator submitted to a breathalyzer, but refused to submit to a drug test. Later, marijuana was found in his possession. We can’t say for certain that he was under the influence of marijuana, but it was in his possession and he refused a drug test.”

WATCH: Robert Mann lead senior scientist with CAMH talks about a study that is looking at the impacts of cannabis on driving.

1:54 Stoned behind the wheel? Study underway looks at effects of cannabis on driving Stoned behind the wheel? Study underway looks at effects of cannabis on driving

The TTC’s tests for THC are based on saliva, unlike the proposed federal impaired driving rules for cannabis, which will measure THC levels in blood.

The TTC based its 10 ng/ml standard on U.S. rules for lack of any Canadian standard to go by, Ross says.

Story continues below advertisement

“Due to the absence of legislation in Canada, the TTC and other safety-sensitive employers are forced to expend significant resources developing drug testing thresholds and methodologies, and defending drug and alcohol testing programs that are necessary to ensure the safety of employees and members of the public.”

However, cannabis intoxication can’t be measured the same way that alcohol can, says Jenna Valleriani, a strategic adviser for Canadian Students for Sensible Drug Policy.

“It’s so dependent on the individual that it’s really hard to tell,” she says. “Cannabis is different, because it’s based on the individual: how experienced they are, the strain that they’re using, how they’re using it.”

“We don’t know how to measure intoxication, so why do we continue to apply the same standards that we use for alcohol to cannabis?” Tweet This

“While we all agree safety should always be a top priority, the American approach of random drug testing does not improve public safety – it’s a fear tactic the TTC is using to give a false sense of security,” union head Frank Grimaldi said in a written statement.

“Our union is growing more concerned by the day that the TTC is exploiting the policy as an abuse of employer power against the hardworking women and men who safely move this city.”

Story continues below advertisement

Grimaldi declined to be interviewed for this story.

And industries whose employees do dangerous jobs are worried about easily accessible legal pot, according to submissions to Ontario’s commission on cannabis legalization released to Global News under access-to-information laws.

“The legalization, commercialization and distribution of cannabis will increase the use among the workforce and, failing an aggressive intervention, will result in more workplace injuries and fatalities,” warned the Ontario General Contractors Association. Tweet This

The contractors called for random testing, as did the Canadian Association of Petroleum Producers and the Ontario Trucking Association.

The province’s Electricity Distributors Association, which represents local electric utilities, warned that its sector is “inherently dangerous.” It said that its members “want to confirm that they can maintain a zero-tolerance policy on employees being under the influence of cannabis and other intoxicating substances while at work.”

And the military, which has its own safety issues to worry about, is studying how to define impairment and what rules to set under legalization.

WATCH: Less than a year ahead of Canada legalizing marijuana some worry police won’t be ready with enforcement tools. Mike Le Couteur has a look at what some provinces are doing and what devices police officers will have on the front lines to crack down on impaired driving.

2:02 No device to detect driving while stoned No device to detect driving while stoned

The courts have wrestled with the question of whether companies can carry out random drug and alcohol testing on all their employees.

Story continues below advertisement

Last April, the TTC won a court victory when a judge upheld its mandatory drug and alcohol testing program against a challenge from its union.

“The evidence satisfies me that there is a demonstrated workplace drug and alcohol problem at the TTC which is currently hard to detect and verify,” Superior Court judge Frank Marrocco wrote.

“The TTC policy … ensures that only employees who are most likely acutely intoxicated due to recent consumption of marijuana will test positive,” he wrote.

The union is fighting the case in arbitration.

The London Underground cut its positive test rate by two-thirds in two years when it brought in random drug testing, Marrocco found.

In Alberta, a similar case went the other way in December, when a judge granted a union request to stop Suncor’s random drug and alcohol testing program. Like the TTC, Suncor says it has a problem with employee drug and alcohol use.

In a 2013 decision, the Supreme Court set national rules for random drug and alcohol testing in a decision that said that employers have to be able to show that they have a widespread workplace problem with substance abuse to legally impose it.

Story continues below advertisement

The TTC isn’t only concerned about drivers, but also with people who work behind the scenes, Ross says.

“Obviously, maintenance has a safety implication. You don’t tighten a lug nut on a wheel properly, there’s a problem. If you’re not checking the signals properly, or switches, there’s a problem.” Tweet This

In its submission to the federal task force on marijuana legalization, the TTC called for a requirement for random testing in safety-sensitive workplaces, with a national registry of positive tests.

However, Valleriani doubts that much will change after legalization.

“It’s based on the assumption that once we legalize we’re opening the floodgates, and suddenly everybody’s going to be coming to work impaired. I don’t think it’s going to work that way. Cannabis is so accessible now that we’re not going to legalize in July and people will be coming in to work intoxicated.”