Nobody yet knows what the full long-term effects of taking cannabis are and legalizing it for recreational use runs the risk of trivializing the dangers for teen consumers, the President of the UN-administered international narcotics watchdog has warned.

In an interview with UN News, Professor Jallal Toufiq also raised the alarm over the continuing proliferation of synthetic opioids on the black market, describing it as the International Narcotics Board’s number one issue - stating the INCB was doing all it can to tackle the scourge.

Khaled Mohamed of our Arabic news service, began by asking him to sum up the impact of cannabis on public health, and the push to legalize it recreationally.