Researchers at the University of Queensland have examined the consumption habits of recent recreational cannabis users to determine how much of the drug typically ends up in a single joint — uncovering considerable variation between individuals.
The study's 31 participants, all of whom had smoked cannabis within the previous 30 days, were asked to roll joints, spliffs, or pack cones exactly as they would in practice, using oregano as a stand-in for cannabis.
Each participant prepared three cannabis-only joints, three cannabis-and-tobacco spliffs, and three cannabis-only cones, in that sequence. Only the consumption methods that participants already had experience with were included — those who had never smoked spliffs, for instance, skipped that portion of the task.
The final sample sizes were 30 for joints, 31 for cones, and 25 for spliffs. All three methods showed substantial variation: joints ranged from 0.1g to 1.25g, spliffs from 0.12g to 1.21g, and cones from 0.03g to 0.41g.
Daily cannabis users rolled approximately three times as much of the substitute herb into their joints compared to less frequent users.
However, because oregano was used in place of actual cannabis, the team could not directly measure THC concentration. When participants were told to treat the herb as though it were more potent, they did not adjust the quantity they used by enough to accurately reflect that difference.
The research team noted that most Australian studies in this area have relied on self-reported frequency of use and basic counts — such as the number of joints or cones smoked per day — as a way of estimating cannabis exposure.
Such measures fail to account for differences in how much cannabis is used or how potent it is, and may therefore give a poor picture of the actual health consequences of use, the researchers argued.
They added: "The amount of cannabis used in common modes of administration may be highly variable. Daily use may be associated with using larger quantities of cannabis.
"The results indicate people may adjust the quantity of cannabis relative to the perceived potency… however, not proportional to THC concentration.
"The variability in quantities prepared shows that the THC exposure from one joint, cone or spliff varies based on individual differences in the preparation of these most common routes of administration.
"Importantly, it underscores the limitations of the current metrics of only asking participants to report the number of joints or cones smoked per day in standard Australian national surveys."
