How much THC is in that joint? A daily diary study of young adults' knowledge of the cannabinoid content of cannabis products.

OBJECTIVE: Many young adults report frequent cannabis use and are at risk for cannabis harms. Knowledge of the tetrahydrocannabinol (THC) and cannabidiol (CBD) concentrations of cannabis products may promote harm reduction, but few studies have characterized cannabinoid concentration knowledge in this population. This study used day-level data to examine predictors of cannabinoid concentration knowledge and associations of cannabinoid concentration knowledge with substance-related consequences among young adults.

METHOD: Participants ( N =131; mean age 22.11 years, 64.12% female) from a larger study of cannabis and alcohol co-use completed daily surveys over 21 days assessing knowledge of the cannabinoid concentrations of cannabis used, forms of cannabis used, motives for cannabis use (medicinal, nonmedicinal, both), and substance-related consequences.

RESULTS: On average, participants reported at least some knowledge of the THC and CBD concentrations of their cannabis on a respective 48% and 32% of their cannabis days. Generalized linear mixed models revealed that participants with a greater propensity to use non-flower (relative to flower) cannabis products and to report medicinal (relative to exclusively non-medicinal) motives for cannabis use reported greater cannabinoid concentration knowledge overall across days, controlling for sociodemographic factors and level of cannabis involvement. Participants with greater overall cannabinoid concentration knowledge reported positive substance-related consequences more often. In addition, participants were more likely to report negative substance-related consequences on days during which cannabinoid concentrations were known versus unknown.

CONCLUSIONS: Findings suggest that cannabinoid concentration knowledge may be higher among young adults who report primarily non-flower and medicinally-motivated cannabis use, although cannabinoid concentration knowledge, alone, may not protect against negative substance-related consequences at the day level.