I'm a proponent for legalizing it, and helping to cripple the illicit economies that surround it, I think as leisure drugs go - it's not so bad. In my experience in recent years, it's cocaine which has increasingly worrying use in most towns and cities, it's gone from party drug of the affluent to common in every club and pub toilet. But weed is more rampant, it's almost normal to habitually smoke it - it's considered as safe if not safer than alcohol, and I know people who started as young as about 14/15 on it. The more we understand the better really. Sounds like a comprehensive study, and something that kids and parents alike should bear in mind!