Giles Dexter of RNZ Large nitrous oxide canisters will automatically be classed as psychoactive substances if they do not have a lawful use, with the government introducing measures to crack down on their misuse. The gas has common legitimate medical and commercial uses, such as for pain relief or anaesthesia, or as a propellant to make whipped cream. But the recreational use of nitrous oxide, or nangs, is illegal under the Psychoactive Substances Act 2013. Despite that, enforcement currently required proof of intent. The government will bring in new rules so proof of intent is no longer required, and all large canisters over 10 grams will be automatically regulated under the act. Health Minister Simeon Brown said the large canisters could contain up to 3.3 litres of gas. "While they are often marketed as 'cream chargers', the Ministry of Health has not identified any legitimate use for them, and has not found evidence of caterers using canisters of this size," he said.…