I understand that you'll be hearing from the CCSA or representatives of it shortly. They no doubt will be able to give you a more detailed response to your question. I think what you'll be hearing from the experts is that there is an emerging field of evidence about the specific and particular harms of marijuana to youth related to the developing brain, and that those effects can have a lasting impact for many years, and potentially for the rest of their lives.
I can tell you that is what you'll be hearing from the scientific experts. I think in terms of effects on people who are older, I understand it's like many of these things, a complicated interaction between the age that you begin the use, the amount that you use, the strength of the product, and certain genetic predispositions, etc.