Legal limits on the amount of cannabis sold per transaction in states with recreational cannabis may promote moderate use and limit diversion. However, state sales limits are heterogeneous and difficult to interpret in terms of tetrahydrocannabinol (THC) dose equivalents.
This cross-sectional study examined how transaction sales limits on recreational cannabis translate to THC doses among U.S. states allowing commercial cannabis sales as of January 1, 2020. Weight-based quantity limits by cannabis type (flower/bud, concentrates, and edibles) were converted into grams of THC content per transaction using known potency values in 2020.
Weight-based sales limits for flower and concentrate vary considerably across states (range=1.0–2.5 oz for flower and 3.5–15.0 g for concentrate), whereas limits for edible cannabis are heterogeneous. A total of 4 states have independent limits for each product category, and 6 states place limits across all products sold in the transaction. Because no states impose limits on the potency of flower or concentrates, the small differences in the weight-based limits translate into large differences in grams of THC allowed to be sold. Assuming a typical dose of 10 mg of THC, current laws allow for sales of up to 560 (Alaska) to 2,283 (Michigan) doses per transaction on the basis of median product potencies.
All states allow a large number of THC doses per transaction, larger than what is typically consumed by daily users over a month. States concerned about public health and diversion should consider reducing sales limits and basing them on total tetrahydrocannabinol content across all purchased products.