Err on the side of cau­tion with pot in the work­place

The Prince George Citizen - - Opinion - GRE­GORY J. HEY­WOOD

Canada is not the only coun­try to le­gal­ize recre­ational mar­i­juana. We now join com­pany with South Africa, Ge­or­gia and Uruguay.

I do not have a per­sonal is­sue with the le­gal­iza­tion of mar­i­juana; I think the po­lice have been ap­pro­pri­ately turn­ing a blind eye to small amounts for per­sonal con­sump­tion for years. It is as nat­u­ral to this prov­ince as red cedar, the Pa­cific dog­wood or the Steller’s jay.

The is­sue for em­ploy­ers is how to man­age the in­ter­face of recre­ational drug use on the week­end or in the evening of a work­day with fit­ness to per­form in the work­place the next day. There are the com­pet­ing rights of the free­dom to con­sume a le­gal com­mod­ity on an em­ployee’s own time and the obligation to show up for work fit and pre­pared to work ef­fi­ciently and safely.

The fed­eral gov­ern­ment has set the Crim­i­nal Code driv­ing lim­its for tetrahy­dro­cannabi­nol (THC) at two nanograms per millil­itre (ng/ml), with an in­creased sanc­tion at five ng/ml. It is worth not­ing that these lim­its are from plasma tests and do not trans­late read­ily to urine or oral fluid swab tests. Em­ploy­ers are un­likely to be draw­ing blood to con­duct test­ing in the fore­see­able fu­ture.

In­stead, work­places typ­i­cally use urine tests, which re­veal THC me­tab­o­lites. In other words, urine tests re­veal the af­ter­math of THC hav­ing been me­tab­o­lized by the body. Typ­i­cal thresh­olds in a drug and al­co­hol pol­icy for urine anal­y­sis is 50 ng/ml for the ini­tial

im­munoas­say test and 15 ng/ml for a lab­o­ra­tory anal­y­sis or gas chro­matog­ra­phy/mass spec­trom­e­try test.

Oral fluid swab tests check for THC in the mouth. As with urine test­ing, there is a two-step process to a pos­i­tive re­sult: an ini­tial thresh­old of four ng/ml, and then a fi­nal thresh­old of two ng/ml us­ing more so­phis­ti­cated test­ing meth­ods. Like the thresh­olds with al­co­hol, these thresh­olds do not mea­sure im­pair­ment but rather seek to mea­sure whether some­one is in­flu­enced by THC.

The ad­van­tage of oral fluid test­ing is that it will re­veal re­cent use. The win­dow of de­tec­tion for oc­ca­sional users is 12 hours, while chronic users show pos­i­tive re­sults up to 24 hours af­ter con­sump­tion. While THC dis­si­pates more slowly in oral fluid than it does in blood, it de­creases rapidly in both fol­low­ing peak con­cen­tra­tions. Stud­ies have in­di­cated that THC con­cen­tra­tion in blood can de­crease by as much as 90 per cent in 90 min­utes.

All of the above begs the ques­tion of what a safe level of THC is for an em­ployee in a safety-sensitive work­place. The me­tab­o­liza­tion of THC for each in­di­vid­ual is not as pre­dictable as it is with al­co­hol. Cog­ni­tive and psy­chomo­tor im­pair­ment is a sig­nif­i­cant risk as­so­ci­ated with mar­i­juana use, and it ap­pears to be re­lated to THC in­gested and lev­els mea­sured in blood or oral flu­ids. Tim­ing and du­ra­tion of im­pair­ment is vari­able but can last for a long time de­pend­ing on many fac­tors. Ac­cord­ingly, there is ar­guably no safe level of THC for those work­ing in a safe­ty­sen­si­tive en­vi­ron­ment.

The RCMP has pro­claimed a 28-day limit. Other first re­spon­ders, in­clud­ing the West Van­cou­ver Po­lice Depart­ment and the mil­i­tary, have im­posed a 24-hour ban on mar­i­juana con­sump­tion prior to ac­tive ser­vice.

Im­pair­ment is a crit­i­cal is­sue in a safety-sensitive en­vi­ron­ment be­cause a mi­nor per­for­mance flaw may re­sult in se­ri­ous in­jury or death. It is also im­por­tant to note that, unlike with al­co­hol, self-as­sess­ment of im­pair­ment from THC is un­re­li­able. Cog­ni­tive ef­fects will per­sist af­ter the more ob­vi­ous eu­phoric or tran­quil ef­fects of THC have sub­sided.

Mea­sur­ing im­pair­ment from THC is a vex­ing prob­lem be­cause there are many vari­ables such as the qual­ity of the prod­uct, method of con­sump­tion and in­di­vid­ual tol­er­ances. But given the im­por­tance of safety in the work­place, ad­ju­di­ca­tors and so­ci­ety gen­er­ally need to rec­og­nize that while the mea­sure­ment of whether some­one is “in­flu­enced” may not be pre­cise in ev­ery case, it is the only avail­able tool to man­age a sig­nif­i­cant safety risk. Let’s all be re­spon­si­ble and be safe.

Gre­gory J. Hey­wood is a found­ing part­ner at Roper Greyell, where he pro­vides strate­gic and prac­ti­cal ad­vice to em­ploy­ers on labour and em­ploy­ment is­sues in the


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