Cigarette Smokers Versus Cannabis Smokers Versus Co-users of Cigarettes and Cannabis: A Pilot Study Examining Exposure to Toxicants.

Introduction Studies suggest tobacco and cannabis co-users may experience greater toxicant exposure than exclusive cigarette (ET) smokers. No study has systematically tested differences in toxicant exposure among co-users, exclusive cannabis (ECa) smokers, and ET smokers. Methods Adult daily cigarette smokers and/or weekly cannabis smokers completed two laboratory visits. Co-users (n=19) tested positive for urinary 11-nor-9-carboxy-Δ 9-tetrahydrocannnabinol (THCCOOH), self-reported cannabis use ≥1x/week, and smoked ≥5 cigarettes per day (CPD). ET smokers (n=18) denied past month cannabis use, tested negative for urinary THCCOOH and smoked ≥5 CPD. ECa smokers (n=16) tested positive for urinary THCCOOH, self-reported cannabis use ≥1x/week, and denied past month tobacco use (NicAlert Results Co-users and ET smokers had higher levels of exhaled carbon monoxide, total nicotine equivalents, metabolites of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNAL), and all four measured mercapturic acids (measures of volatile organic compounds) than ECa smokers (ps .05). Discussion Co-users and ET smokers demonstrated comparable levels of biomarkers of exposure to harmful constituents despite smoking similar amounts of tobacco. ECa smokers demonstrated lower levels of toxicant exposure for most biomarkers.