The legalization of marijuana has many in the construction trades worried about safety in the workplace.  As Canada enters this new era, questions are rolling out about how employers will deal with pot on the job and whether job safety will be compromised.

Those who work in industry say they're not naive enough to think people aren't using now on the job.  But the concern is that once it's legal, even more workers may be high at work - and, as yet, there's no way to tell.

“You can imagine the damage, the catastrophe you can cause because you're higher than a kite.”

It's a pretty dire warning for students at the North American Transport Driving Academy but their instructor Marc Morris wants to get the message across to these truckers-in-training:  that pot and driving don't mix.

“I think it's going to have a huge effect on this industry, a huge effect,” says Morris.

Morris says he knows some truckers are driving high already but he believes legalizing pot will open the floodgates.

“We're going to legalize it? Oh boy, now what are we going to do?” he says, “You've got someone going down the highway with 80 to 100,000 pounds behind them, travelling at 105 km/hour and half stoned or fully stoned.”

The trucking industry isn't alone in its concerns about pot in the workplace.

Richard Hayter is with the Building and Construction Trades Council, “Anyone who drives a vehicle or walks in front of a vehicle, everyone should have a concern about what the impacts will be in the community.”

A few months ago, the United Association of Plumbers, Pipefitters, Pipeline Workers and Welders Local 71 hosted a seminar about marijuana on the job.  The seminar was packed with apprentices.

Brent Payne is the business agent of UA Local 71, "It’s a huge concern,” he says, “because we don't know what to expect yet and we don't know if the government knows what they're expecting.”

Martin McNaughton is a plumbing foreman and says there are already concerns about employees on the job under the influence of marijuana.

“For us it's “fit for duty,” says McNaughton, “and unfortunately one of our concerns is that the only way we can measure that is when someone is hurt or killed.”

The law is pretty clear:  drug testing isn't permitted in the workplace unless an employee agrees to it or its part of a collective agreement.  Labor lawyer Mario Torres says employers are going to have to justify how safety in the workplace trumps the privacy and rights of employees.  Torres says the more dangerous the workplace, the more likely the employer is to win that argument.

And, so companies like SafetyScan Technologies are rolling out technology, preparing for October 17th.  Safety Scan Technologies says its eye scan can detect drug and alcohol impairment in 30 seconds.

Randal Roberts is the President and CEO of SafetyScan Technologies, “Companies like BHP Billeton and Barrick Gold are using it on a daily basis to test workers in mines,” he says. 

“We've done millions and millions of tests using the system; it’s proven, easy to use and obviously effective.”

There's some comfort in that for the student truck drivers who want to know those using will be caught.

“There's no if, ands or buts,” says Saverio Lacquaniti, a student transport-driver-in-training, “People are doing it all the time and it makes it harder for us to stay safe on the road when people are under the influence.”

While most workers aren't advocating drug testing, there is a worry that with no clear guidelines at the moment, drug use on the job will only get discovered once someone is hurt or killed.