Colorado lawmakers have approved an expansive bill that would tighten medical marijuana rules and mandate research into the mental health effects of high-THC marijuana products.

On June 8, the state House unanimously approved Senate amendments to House Bill 1317, passing the measure out of the Colorado Legislature and sending it to Governor Jared Polis. Attracting plenty of attention from both sides of the marijuana aisle, the bill had been heavily amended after its introduction by House Speaker Alec Garnett in May, and changed 29 times during House and Senate discussion.

If signed by Polis — his administration hasn't commented on the measure — the bill will add several additional layers of protocol for medical marijuana recommendations, including a required THC dosage amount and added medical and mental health reviews. The measure would also institute new packaging requirements for commercial marijuana concentrates and create an expanded tracking system for patient purchases.

More state restrictions on concentrated THC products had been pushed by lobbies representing parents, public educators and health-care representatives as Colorado health professionals declared a state of emergency in youth mental health and Colorado Department of Health and Environment data showed that the use of extracted marijuana products more than doubled among teenagers from 2015 to 2019.