Experts are increasingly expressing concern that marijuana is damaging young people.

THC levels in modern marijuana is far higher than in past decades and that’s a problem for young people whose brains are fragile and still developing.

Dr. Mark Ware treats patients who benefit from medical marijuana but he says the follow-up on legalized medical use in Canada is still lacking and teens might be at risk of damage.

“If you wait until you're 25 it appears those risks really drop away. But while the brain is forming, connections are forming and learning to work in this crazy society of ours. You should not put something in there that can change the way you interact with society. Brains are too important,” said Ware.

Addiction is also a serious issues, as about 10 percent of pot users will become addicted but that percentage is seven percent higher those who begin using weed as teens.

THC has also been linked to the onset of psychosis.

“The earlier they start the more likely they are to develop psychosis, at least twice as much, studies say more,” said psychiatrist Amal Abdel-Baki.

Other experts interviewed at a recent pot conference in Montreal concurred.  “Personally I'm convinced we need regulation for any substance,” Serge Brochu of the University Of Montreal told CTV Montreal.

“It's about time for our public policy to catch up to the scientific evidence on the issue," said Adam Greenblatt of Sante Cannabis.

Watch Caroline Van Vlaardingen's full report for more details.