Recreational cannabis will be available to people ages 21 and over to buy legally around the state next year, if regulators stay on schedule. As more and more states have legalized cannabis, a wide variety of products have entered the market — some with high levels of THC. Some public health experts are raising concerns about the potential risks of heavy cannabis use — that includes addiction as well as other mental and physical health issues. A summit dedicated to this very topic is happening Friday at Hazelden Betty Ford Treatment Center in St. Paul. Hamline University psychology professor Serena King is the organizer and she joined the program.