Estimating THC Consumption from Smoked and Vaped Cannabis Products in an Online Survey of Adults Who Use Cannabis.

Introduction: Quantification of consumption patterns of the primary psychoactive compounds in cannabis, which cause euphoria or intoxication, is sorely needed to identify potential risks and benefits of use and to provide meaningful safety information to the public. The diversity of products available, multiple methods of administration, and lack of labeling of products have made such quantification challenging. Our group is developing a survey instrument for estimating the quantity of delta 9-tetrahydrocannabinol (THC) consumed in population samples, which is flexible and incorporates individualized reports of patterns of consumption. This study provides an illustration of a procedure for translating self-reported consumption into milligrams of THC (mgTHC), which may serve as a working model for future quantification efforts. Methods: Social media advertising was leveraged to enroll 5627 adults who use cannabis into an online, anonymous survey study. Only those who used cannabis in the past 7 days, used flower or concentrate products, and who chose to report their quantity of use in hits per day or grams per week ( n =3211) were included in this report. Formulas were used to estimate mgTHC used per day, in hits per day or grams per week; potency (%THC); constants for estimating the amount of material consumed for each hit; and a method of administration efficiency constant to account for THC loss due to the administration method. Results: The estimate for mgTHC used per day was M =92.8 mg/day (SD=97.2 mg; 1st-3rd quartile range=25-132 mg). The estimated quantity of use was much lower for those reporting in hits ( M =43.7 mg, SD=43.8) than for those reporting in grams ( M =115.1 mg, SD=107.0). The estimated rate of binge use in the past week, arbitrarily defined as more than 50 mgTHC within any one daily time quadrant, was 6.8%, which increased to 29.3% if 25 mgTHC was used. Conclusions: The approach illustrated in this study goes beyond existing cannabis measures by asking participants to provide highly detailed estimates of their past 7-day use patterns and then applying a logical formula to translate this information into mgTHC. This initial procedure has limitations and lacks generalization; however, we hope this demonstration stimulates testing of similar approaches and relevant laboratory experiments that will enhance the validity of cannabis consumption estimation procedures.