Meier E, Tessier KM, Luo X, et al. - This study was undertaken to investigate variations in toxicant exposure among co-users, exclusive cannabis (ECa) smokers, and exclusive cigarette (ET) smokers. Researchers compared first morning urinary tobacco and combustion-related biomarkers of exposure following a cannabis/tobacco smoking session (visit 2). This study’s findings demonstrate Co-users and ET smokers demonstrated comparable levels of biomarkers of exposure to harmful constituents despite smoking similar amounts of tobacco. For most biomarkers, ECa smokers indicated lower levels of toxicant exposure.