Mean + standard deviation (SD) concentrations on a log-scale for ∆9-tetrahydrocannabinol (THC), 11-hydroxy-THC (11-OH-THC), and 11-nor-9-carboxy-THC (THCCOOH) in n=11 frequent (left) and n=9 occasional (right) smokers up to 72 and 54h, respectively, after smoked, vaporized, and oral cannabis (6.9% Δ9-tetrahydrocannabinol, THC; ~50.6mg THC) administration (0 h). Horizontal lines present at the limits of quantification (LOQ; 0.2 µg/L for all, except 15 ng/L for THCCOOH) and OF THC cutoffs for DRUID (1 µg/L) and SAMHSA (2 µg/L).