Pot presents unique dan­gers when driv­ing un­der its in­flu­ence

Cannabis af­fects driv­ers’ per­cep­tion of time and space, writes

Calgary Herald - - DRIVING - Lor­raine Som­mer­feld. Driv­ing.ca

On Oct. 17, 2018, the sky will fall — in Canada. That’s ac­cord­ing to the anti-pot le­gal­iza­tion crew, any­way. They are pre­dict­ing that chaos — in the form of some ground up bud rolled into a small cig­a­rette — will be un­leashed on our road­ways.

A re­cent Statis­tics Canada sur­vey re­veals nearly 16 per cent of Cana­di­ans have con­sumed some form of cannabis in the past three months. Guess what? Lots of Cana­di­ans smoke weed, and the sky is still in­tact.

Dr. Andrea Furlan, an as­so­ciate doc­tor of medicine at the Univer­sity of Toronto and a Toronto Re­hab Foun­da­tion sci­en­tist, isn’t pan­ick­ing. Furlan has done ex­ten­sive work with opi­oids and med­i­cal mar­i­juana, and her work with Toronto Re­hab al­lows for as close to real-world ex­per­i­men­ta­tion as you can get; the iDAPT DriverLab is one of the best driv­ing sim­u­la­tors in the world.

She’s quick to note that pot isn’t al­co­hol, and both users and the le­gal sys­tem will have some grow­ing pains if they try to use one tem­plate for the other.

“Al­co­hol and cannabis af­fect dif­fer­ent parts of the brain. Those who con­sume al­co­hol and get be­hind the wheel are more likely to take greater risks, to be ag­gres­sive. Cannabis slows you down. We see people driv­ing more slowly and leav­ing greater dis­tances be­tween them­selves and other driv­ers,” she ex­plains.

Sounds al­most like a good thing, given the num­ber of tail­gaters, no?

No. Ac­cord­ing to Furlan, “when these drugs are used so­cially, we tend to see people us­ing them to­gether. Be­cause they work on dif­fer­ent parts of the brain, dif­fer­ently, there can be im­pair­ment even if both “le­gal” lev­els for al­co­hol and cannabis are within ac­cepted lev­els.”

This will be the tricky road that po­lice and the courts will be nav­i­gat­ing. A po­lice of­fi­cer I spoke to about the sub­ject chose his words care­fully, re­mind­ing me that po­lice are look­ing for im­pair­ment of that in­di­vid­ual driver’s in­abil­ity to safely and legally op­er­ate a ve­hi­cle.

We will still be see­ing road­side so­bri­ety tests — stand­ing on one leg, walk­ing and turn­ing, find­ing your nose with your fin­ger — though Canada is also set to roll out the saliva-test kits they tested last year. A spit test will show signs of the Big Six most com­monly abused drugs: cannabis, am­phet­a­mines, metham­phetamines, co­caine, opi­ates and ben­zo­di­azepines.

If you’ve ever been drunk, you know how long un­til it clears your sys­tem. I’ve seen RIDE checks op­er­at­ing at 7 a.m. around hol­i­days, be­cause of­fi­cers know there are still driv­ers with high enough blood-al­co­hol lev­els to zing the ma­chine.

Furlan’s re­search points to an­other wrin­kle in the test­ing for, and pre­vent­ing abuse of, pot.

“Cannabis has many strains, and many med­i­cal in­di­ca­tions. It can be smoked or in­gested, and it’s stored in the body in adi­pose tis­sue. Whereas es­tab­lish­ing 0.08 ( blood-al­co­hol limit) as im­paired for al­co­hol con­sump­tion is fairly straight­for­ward, there are many fac­tors that com­pli­cate a sim­i­lar mea­sure for cannabis.”

The pa­tients Furlan pre­scribes med­i­cal mar­i­juana for would nec­es­sar­ily have the pres­ence of the drug reg­is­ter in their sys­tems, though it is un­likely it would be at the level of im­pair­ment. She still tells them not to drive for four hours af­ter their last toke, and warns them their charts in­di­cate that warn­ing in case they think she’ll back them up for abus­ing the drug in the event of a col­li­sion.

The Stats Can study that re­veals that 16 per cent of Cana­di­ans have used cannabis didn’t sur­prise her, but the fact that one in seven of those users had got be­hind the wheel within two hours of us­ing, did.

“We have to bring science to this dis­cus­sion, es­pe­cially with younger driv­ers. They think that be­cause they’re more re­laxed, they’re bet­ter driv­ers when they smoke or in­gest cannabis. Younger driv­ers tend to think that be­cause it’s le­gal, it’s safe.”

Your pot-ad­dled brain may mean you drive slower and leave more dis­tance ahead of you, but it also dis­torts your per­cep­tion of time and space. Your re­sponse time is bad, though your judg­ment is not im­paired; you know you’re im­paired. Al­co­hol is the flip side of the coin: it im­pairs your judg­ment, so you do not be­lieve you are im­paired. Furlan’s warn­ing about the pop­u­lar­ity of com­bin­ing the use of the two drugs is where com­mu­ni­ties (ci­ti­zens, po­lice, le­gal) will have to find a way to rec­og­nize im­pair­ment, not just lev­els of pres­ence.

Furlan and her col­leagues will con­tinue to do work with the iDAPT DriverLab, where they can test the im­pact of the many uses of cannabis for pain man­age­ment, as well as recre­ational use.

This is how she pri­or­i­tizes her mes­sage: Just be­cause cannabis is le­gal, like al­co­hol, its sale and use will be con­trolled and mon­i­tored for a rea­son.

Be­cause so many people com­bine the two sub­stances, they should be aware that while tech­ni­cally reg­is­ter­ing within ‘safe’ le­gal zones on both prod­ucts, they can still be — and be found to be — im­paired. An of­fi­cer is con­sid­ered an ex­pert wit­ness in a court of law.

Those con­sum­ing cannabis for med­i­cal pur­poses should heed their doc­tor’s di­rec­tion on safety re­gard­ing driv­ing, though they are un­likely to be con­sid­ered im­paired un­der nor­mal cir­cum­stances, just as with other phar­ma­ceu­ti­cal drugs.

Test­ing of body flu­ids for de­tec­tion of cannabis is not as straight­for­ward as test­ing for blood-al­co­hol con­cen­tra­tion.

Do not drive for at least four hours af­ter your last toke, or for 12 hours af­ter you’ve in­gested ed­i­bles. If you’re loopy or tired, don’t drive at all.


Al­though cannabis doesn’t im­pair a driver’s judg­ment the way al­co­hol does, the drug does slow the re­sponse time of users who are un­der its ef­fects.


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