Standard tetrahydrocannabinol units: an idea whose time has come.

Abstract

The increasing diversity of cannabis products represents a challenge for measuring and reporting potency. Freeman & Lorenzetti's proposal for a standard tetrahydrocannabinol (THC) unit has considerable potential as a tool for reporting potency with respect to market surveillance and sales data, as well as in research studies. Although no standard unit can fully capture the qualitative differences across modes of administration, a 5-mg THC unit represents an appropriate threshold for communicating the potency of cannabis products. This commentary discusses a proposal from Freeman & Lorenzetti on the use of standard units of tetrahydrocannabinol (THC) for cannabis products [1]. With the advent of legal cannabis markets, regulatory authorities and the industry have a shared responsibility to ensure that consumers have adequate information regarding the potency and appropriate dose of products [2]. Effective consumer guidance is particularly important, given the proliferation of cannabis products and the wide range of tetrahydrocannabinol (THC) levels, which range from less than 1% to more than 90% [3]. Within this context, there is a need to standardize how cannabis potency is reported. Freeman & Lorenzetti propose a ‘standard THC unit’ of 5 mg of THC for all cannabis products. The authors point to the use of standard alcohol units as a framework; however, the nicotine market provides a more appropriate reference point given the diverse modes of administration for both cannabis and nicotine products, which include transdermal, oral ingestion, vaporized aerosol and smoke inhalation. A key question raised by Freeman & Lorenzetti is whether a 5-mg THC unit has the same meaning among these modes of administration, given inherently different pharmacological effects. Ultimately, there may be no way of reconciling these differences within a standard quantitative unit: modes of cannabis use differ not only with respect to the onset and duration of ‘peak’ THC effects, but also in the qualitative effects of THC. Nevertheless, even an imperfect standard unit would represent a considerable improvement on the status quo, in which consumers typically depend upon word of mouth and references to cannabis ‘strains’, which are unreliable indicators of cannabis potency [4, 5]. Standard THC units have the potential to serve as a common metric for reporting market-based data among different product categories, such as sales volumes and prices paid per unit. Standard THC units could also be integrated into product labelling as a consumer information tool. Currently, few consumers understand the THC numbers that serve as the basis of potency labelling in legal cannabis markets, in part because THC numbers are communicated using different units among different products, including dried herb, oils and edibles [1]. Although these practices are technically sound, consumers have little idea of how to interpret and apply these numbers to guide consumption levels. Alternatively, regulators could label the number of standard THC units in a particular product, such as a joint, edible or unit of oil, which is likely to be more intuitive for consumers [6]. Standard units could also enhance the way cannabis consumption is reported in epidemiological and clinical studies, most of which rely upon crude measures of frequency of use, without an established means of comparing different modes of administration. Freeman & Lorenzetti pose the question of whether 5 mg is the appropriate threshold for a standard THC unit. As the authors note, there are regulatory precedents in several US states for using 5 mg of THC as a standard ‘serving size’ for cannabis edibles, while other states and Canada use 10 mg of THC as a standard unit for serving size and packaging regulations. There is a compelling argument for a standard THC unit to be at, or below, the point of intoxication for most consumers [2]. For example, the amount of alcohol in a ‘standard drink’ is below the level that would induce intoxication or impairment for most consumers. A standard of 5 mg rather than 10 mg THC is more consistent with this principle and allows consumers to ‘titrate’ up to their desired level of consumption. Overall, Freeman & Lorenzetti's proposal for a standard THC unit has considerable merit and represents an opportunity to harmonize the ways in which cannabis potency is reported across the increasing number of jurisdictions with legal cannabis markets None.