Justice Committee on Sept. 18th, 2017

[Murray Rankin, NDP, Victoria, BC]

We're talking about cannabis primarily, but of course the impairment could be from other new psychoactive substances. Is it possible that the drug-screening devices we're talking about could address other kinds of impairment? I'm thinking about opioids, methamphetamines, cocaine, and the like. How are we going to grapple with that? If you believe in per se limits, do we have scientific evidence for what those numbers should be?

[Prof. Robert Mann]

Well, we do. Evidence from several sources goes into setting per se levels. That's evidence from basic laboratory studies of the impact of these drugs on skills, evidence from effects on driving performance or simulated driving performance, and then epidemiologic studies on the impact of having a drug on board on collision risk.

It's important to recognize that the key piece is the epidemiologic studies showing what the drug does to collision risk. We all know that having a good reaction time is required for safe driving. You see that if the driver in front of you slows down or stops, you need to react fast to slow down too. If amphetamines actually improve your reaction time in a laboratory situation, does that mean we should not have a per se level for amphetamines and maybe encourage people to use amphetamines and drive? No, because when we look at the epidemiologic studies, we see that drivers with amphetamines on board are more likely to be involved in collisions.

We need that range of evidence, and that substantial evidence is out there.

[Murray Rankin, NDP, Victoria, BC]

We've had the alcohol test committee in Canada which for 50 years has been looking at breath-testing equipment. We have a pretty good sense that they are reliable and trusted by the legal and scientific communities.

However, here we are at the threshold of new technology with these new devices, and we're going to make significant decisions based on what they tell us. Turning from the levels to the reliability of the equipment, one hears that there are big problems when it gets cold in a country like Canada, that it produces a lot more false positives than otherwise would be the case.

I guess I'm wondering whether you think we're at the right place and time to rely on this equipment instead of the old field sobriety tests or some variation on them to address drug impairment.

[Prof. Robert Mann]

My perspective is that we should give the police as many good tools as we can to use these laws, and I would include oral fluid tests in that. It's true that they are a newer technology than breath tests that we've had for alcohol for many years, but they have been used in other countries for perhaps a decade now. They have been field tested in Canada, and my understanding is that as a result of the field test, it was suggested that some were suitable for Canadian use.

[Murray Rankin, NDP, Victoria, BC]

Could I ask one final question, or am I out of time?

[The Chair, Liberal, Anthony Housefather]

You are out of time, but you can have one very quick question.

[Murray Rankin, NDP, Victoria, BC]

We have so many different kinds of tests. The law that we're talking about refers to a sample of oral fluid or urine. Saliva, urine, blood, even sweat, are things that could indicate drug use. Is one more reliable than the other? Is a blood test more reliable than a urine test, for example?

[Prof. Robert Mann]

Well, a blood test is considered the gold standard. For a criminal charge or conviction, I think that's what's being considered. However, I think the oral fluid tests will facilitate detection of impaired drivers and make the lives of police officers a lot easier.

[The Chair, Liberal, Anthony Housefather]

Thank you very much.

Mr. Ehsassi.

[Ali Ehsassi, Liberal, Willowdale, ON]

My first question would be for Mr. Mann.

I am wondering if you could explain to us whether there is a lag time between the use of cannabis and the impairment of one's senses.

[Prof. Robert Mann]

There are suggestions that this is the case.

In our lab, we've looked at smoked cannabis, and we find that it goes into the blood very quickly. In five minutes after people smoke a cannabis cigarette, they achieve their peak blood THC levels. It declines relatively rapidly after that.

When we ask them if they feel the effects of the drug, we find there is a slight lag. It increases for a little bit beyond that five-minute window, and then it too begins to decline within a half an hour or so. There is this perhaps slight lag in terms of the impact on the self-reported sense of the effects of the drug, and it may be that there is, as well, for behavioural effects of the drug.

[Ali Ehsassi, Liberal, Willowdale, ON]

How does that compare to alcohol use? What are the lag times there?

[Prof. Robert Mann]

For alcohol, what we typically see is the effects of the drug are most pronounced on the rising limb of the BAC curve, and then once the BAC peaks, the effects on the falling limb of the curve at the same BAC are somewhat less pronounced than we typically see in the rising limb of the curve.

[Ali Ehsassi, Liberal, Willowdale, ON]

Thank you.

Perhaps I could ask a question of Dr. Brubacher.

We heard incredibly disturbing testimony an hour ago about how a company had actually done an internal survey and they had questioned youth aged 18 to 35 on what their impressions were of drug use on driving. Evidently, 20% of the respondents had said that they thought cannabis use would either not affect their driving abilities or perhaps would even enhance their driving abilities.

Could you speak to that issue for the record?

[Dr. Jeff Brubacher]

I think that is a perception out there—

[Ali Ehsassi, Liberal, Willowdale, ON]

A perception.

[Dr. Jeff Brubacher]

Yes, that cannabis is not a big problem when it comes to driving. It's not true. All the evidence suggests that it does increase crash risk, approximately doubles crash risk in cannabis users. It's far worse if you use it together with alcohol. I guess some of that perception may be in comparison with alcohol, where we know that the crash risk goes up exponentially at higher alcohol levels. Cannabis is not as bad as alcohol in terms of causing an increased crash risk, but it certainly does cause an increased crash risk.

[Ali Ehsassi, Liberal, Willowdale, ON]

Thank you.

[Dr. Jeff Brubacher]

It's just perception, yes.

[Ali Ehsassi, Liberal, Willowdale, ON]

Another question that also has to do with perceptions is that some people are of the view that if they don't feel impaired, then they're perfectly fine to drive. What would you say to that?

[Dr. Jeff Brubacher]

Well, I think impairment sometimes impairs your ability to judge yourself, and it's often the case that people think that they're fine when they're not. So, no, that's not good advice.

[Ali Ehsassi, Liberal, Willowdale, ON]

Okay.

Last, how long does the effect of THC last, actually?

[Dr. Jeff Brubacher]

Bob may be able to speak to this better than I can, but usually after you smoke it...approximately four hours longer after you take it orally, so up to eight hours, I think, after oral use.

I'll turn it over to Bob, if he wants to....

[Ali Ehsassi, Liberal, Willowdale, ON]

Sure, absolutely.

[The Chair, Liberal, Anthony Housefather]

Mr. Mann, do you have an answer?