Standard units for grading the potency of cannabis – similar to those already used for alcohol – would result in significant improvements in the mental health of users, according to addiction experts. Researchers from the Addiction and Mental Health Group at the University of Bath, working with staff from King’s College London, UCL and the Australian Catholic University in Melbourne, say more needs to be done to make people aware of the levels of THC – the main psychoactive component – in the cannabis they are consuming. Writing in the journal Addiction, the experts suggest a unit level should be set at 5mg of THC – the amount that would typically be found in a small joint. This is enough to induce intoxication but without psychotic symptoms. (See also: Making cannabis safer)