Self-rating questionnaires show a significant difference in the frequency and amount of cannabis consumption between the groups of regular and occasional smokers. However, they do not differ in age, in the years of cannabis use and or in the age at which consumption started (Table 1). The median value of the self-reported usual amount of cannabis smoked by regular users is higher than that of occasional consumers (0.4 g vs 0.3 g). The determination of cannabinoid time profiles revealed that the THCCOOH median level was significantly higher in regular smokers compared with occasional users (21 μg/l vs 0 μg/l just before smoking the joint). An equal difference was found for the participants enrolled in the same study and selected by Fabritius et al, (2013a) for the pharmacokinetic determinations.
