Pot breath­a­lyzer

Build­ing a breath­a­lyzer for weed re­quires the best study ever

Bloomberg Businessweek (Asia) - - FRONT PAGE - Story Karen Weise

In states such as Washington and Colorado, the le­gal­iza­tion of recre­ational mar­i­juana use has brought a shadow mar­ket into the open. If you’re into this sort of thing, it’s prob­a­bly made you a lot less para­noid. But as more peo­ple legally smoke up, state and local law enforcemen­t face a buz­zkill: There’s no quick way to know if a driver is stoned.

That’s partly be­cause the science of highs is sketchy. A May study from the AAA Foun­da­tion for Traf­fic Safety con­cluded that there isn’t a re­li­able link be­tween im­pair­ment and the level of THC, pot’s psy­chotropic agent, in a driver’s blood. None­the­less, in Washington, as in many states, the le­gal limit is based on blood con­cen­tra­tion. So of­fi­cials are look­ing to a sep­tu­a­ge­nar­ian chemist to build a breath­a­lyzer for weed. The chemist’s name, of course, is Herb.

Herb Hill, a pro­fes­sor at Washington State Univer­sity, has spent more than four decades pi­o­neer­ing ways to de­tect chem­i­cals—or, more ac­cu­rately, to de­tect chem­i­cal sig­na­tures based on the move­ment of a sub­stance’s com­po­nent ions. His work helps var­i­ous government and mil­i­tary in­spec­tors swab lap­tops for ex­plo­sives, sniff out mold-con­tam­i­nated food, and find sarin gas on a bat­tle­field. As he pre­pares to re­tire next year, Hill and his last grad­u­ate stu­dent, Jes­sica Tu­fariello, are ap­ply­ing his tech­niques to test for pot.

To­day, if cops in Seat­tle sus­pect a driver has ex­ceeded the le­gal limit (5 nanograms of THC per mil­li­liter of blood), they must call for spe­cially trained col­leagues to run a 12-point test ex­am­in­ing the sus­pect’s light sen­si­tiv­ity, eye­lid tremors, balance, and other fac­tors. Then they’ll need a search war­rant to draw a sam­ple of the sus­pect’s blood at a nearby hospi­tal. The whole process can take hours, dur­ing which the drug could dis­si­pate in the blood­stream. A breath­a­lyzer could mea­sure drug lev­els in the blood­stream or at least quickly de­ter­mine whether a blood draw is war­ranted.

“It’s an in­ter­est­ing project to end on, and an im­por­tant one,” Hill says, though he ac­knowl­edges the 5ng level he’s test­ing for is an un­sci­en­tific le­gal guide­line. “I haven’t seen any­body who has de­ter­mined how that re­lates to be­ing im­paired.” He be­gan think­ing about build­ing a breath­a­lyzer for drugs in 2009 at the sug­ges­tion of his friend Nick Lovridge, a re­tired WSU po­lit­i­cal science pro­fes­sor who’d been do­ing re­search for the state on ways to re­duce high­way fa­tal­i­ties.

The chem­istry pro­fes­sor was al­ready plan­ning for retirement, so he asked Tu­fariello for help. The pair orig­i­nally planned to test for 10 com­mon il­licit sub­stances but nar­rowed their fo­cus to THC in 2012, af­ter Washington vot­ers ap­proved a bal­lot mea­sure le­gal­iz­ing pot. Hill says he’s se­cured about $300,000 in fund­ing com­mit­ments from Chem­ring Group, a Bri­tish defense con­trac­tor with U.S. di­vi­sions that pro­duce de­tec­tion de­vices for chem­i­cal and bi­o­log­i­cal agents. In ex­change, Chem­ring has ex­clu­sive rights to use his and Tu­fariello’s work to de­velop a com­mer­cial breath­a­lyzer.

The sci­en­tists are re­ly­ing on a tech­nique called dif­fer­en­tial mo­bil­ity spec­trom­e­try (DMS), which gen­er­ates two elec­tric fields de­signed to keep THC ions flow­ing to a sen­sor at the end of a tube. The first field’s charge al­ter­nates be­tween strong pos­i­tives and neg­a­tives, at­tract­ing and re­pelling mol­e­cules. The se­cond field’s charge is cal­i­brated to coun­ter­act those fluc­tu­a­tions, mean­ing, as Hill

says, “the THC makes it through, but the other ions don’t.” First, the re­searchers tested a pure THC sam­ple that’s com­mer­cially avail­able in con­cen­tra­tions far too low to get high, and it pro­duced the strong sig­nal they’d hoped to see, in­di­cat­ing that mar­i­juana can be de­tected us­ing DMS. Then came the hard part—or the fun part if, again, you’re into this sort of thing: the field tests. “When you breathe into a tube, every­body is go­ing to have a dif­fer­ent set of chem­i­cals that come out,” says Jeff Okamitsu, Chem­ring’s chief technology of­fi­cer, who’s over­see­ing the com­mer­cial­iza­tion ef­forts. To make sure the ma­chines wouldn’t yield false pos­i­tives, Tu­fariello tried to repli­cate a mar­i­juana smoker’s munchies. “I would go eat at Taco Bell and Thai Gin­ger and drink lots of cof­fee to con­tam­i­nate my breath,” she says. So far, so good. None of the other stuff pro­duced a sig­nal sim­i­lar to THC. A univer­sity board ap­proved the lab’s hu­man test­ing pro­to­col in 2014. Tu­fariello says she had no prob­lem find­ing 14 stu­dents will­ing to get high for the sake of science and pocket money. Fed­eral re­stric­tions made things a lit­tle more com­pli­cated, though. The re­searchers couldn’t sup­ply the pot, do the test­ing on cam­pus, or ex­plic­itly pay vol­un­teers to smoke. “We had to be very clear that we are pay­ing peo­ple for their time,” she says. So Tu­fariello got cre­ative. Tech­ni­cally, vol­un­teers made $10 each for hav­ing their breath mea­sured be­fore and af­ter smok­ing weed. They’d call her be­fore­hand, she’d hus­tle over to get a pre-toke breath sam­ple, and then she’d test again af­ter the pot but, when pos­si­ble, be­fore the Dori­tos. Many of the test sub­jects didn’t smoke alone, so who­ever made the run to the dis­pen­sary got an ad­di­tional $15 be­cause that per­son was “a more ded­i­cated vol­un­teer,” Tu­fariello says. She asked ev­ery­one to use a strain called Blue Dream, which is easy to grow and varies lit­tle be­tween sea­sons. (For the record, Blue Dream is the most pop­u­lar strain for sale in Washington and Colorado, pro­duc­ing a “cere­bral high, not too strong but quite up­lift­ing,” ac­cord­ing to High Times.) The DMS anal­y­sis iden­ti­fied THC in 81 per­cent of the sam­ples. In one case the re­searchers found THC be­fore the vol­un­teer had even started smok­ing, but it turned out he’d for­got­ten to men­tion he’d smoked at break­fast. Last year, Chem­ring sent the lab new tools, in­clud­ing a breath-cap­tur­ing de­vice that looks like a glue gun. They re­peated the pro­ce­dure, and the re­sults im­proved: THC was de­tected 89 per­cent of the time. The WSU team is start­ing an­other set of tests to cor­re­late the THC lev­els found in the lab with blood sam­ples drawn at a hospi­tal. “That will be in­cred­i­bly valu­able,” says Okamitsu, Chem­ring’s CTO. “That lets me look at what is the small­est amount of THC we can de­tect.” His team and Hill’s talk weekly, and Chem­ring hopes to have a breath­a­lyzer pro­to­type for police of­fi­cers to field-test this fall. Their lat­est model looks a lit­tle like an old-school Game Boy, with the sus­pect asked to blow into a tube on the side where the vol­ume knob would have been. One area that still needs ad­di­tional re­search: fig­ur­ing out ex­actly how pot use af­fects peo­ple’s abil­ity to drive. A 2015 study from the National High­way Traf­fic Safety Ad­min­is­tra­tion con­cluded that mar­i­juana users don’t have an in­creased risk of crash­ing af­ter ad­just­ing for fac­tors such as age and al­co­hol use. Yet a 2013 study from the National In­sti­tutes of Health found that pot can slow re­ac­tion times, es­pe­cially among ca­sual users, and the May AAA study found that in the first year af­ter Washington le­gal­ized pot, driv­ers in­volved in fa­tal crashes were twice as likely to have THC in their blood than in the three prior years. (Many also had al­co­hol in their sys­tem.) For law enforcemen­t, at least, the breath­a­lyzer can’t come soon enough. When­ever Lovridge, the po­lit­i­cal science pro­fes­sor, meets with state of­fi­cials and of­fi­cers, “they say, ‘How is that thing com­ing? Is it ready yet?’” He laughs. “I say, ‘Science takes time.’” <BW>

The pro­to­type of Chem­ring’s pot breath­a­lyzer looks a lit­tle an old- school like Game Boy

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