Most of us want to know how strong an alcoholic drink is before we consume it, which is made simpler by having a standardised system. ABV, or alcohol by volume, is the accepted way of measuring and communicating alcohol potency.
Unlike alcohol, cannabis has no standard measurement of strength. It would be odd to think of only finding out how strong an alcoholic drink is once you’ve already consumed it, but that’s exactly what people who use cannabis have to do.
Although recreational use of cannabis is illegal in the UK, it is hardly a niche activity. In England and Wales, 30 per cent – that’s around 10 million – adults aged 16 to 64 have tried the drug at least once, according to the annual crime survey. Across the Atlantic millions more have access to cannabis as most US states allow medical and/or recreational use of the drug.
The benefit of regulated markets for American consumers is they are given information about the strength of the cannabis products they can buy. In the main, this is done by suppliers indicating the amount of tetrahydrocannabinol (THC) in their products. So, THC has become the equivalent of ABV for alcohol. Instead of spirits and beers, there are low and high, forgive the pun, THC products.
Having a standard way of displaying the strength of a drug doesn’t just help consumers make purchasing decisions, it can also be used to help them understand risks. For over 30 years, successive governments have advised us on safe levels of drinking by using alcohol units as a standard. Although even with such well-established standards, not everyone is clear about what exactly a unit of alcohol is, let alone whether they heed the advice on the number they should limit themselves to.
Ian Hamilton lectures in mental health at the Department of Health Sciences, University of York