New Anti-Marijuana "Study"?

[Astrovan]

Came across something while looking for primary results:

http://www.cbc.ca/health/story/2008/...umdisease.html

I'm already suspicious, because I see nothing about mentioning what degree of tobacco the participants also took. Alot of "marijuana is bad 4 u!" studies I've seen failed to mention that their participants smoked 3 times as much tobacco as they did marijuana, which in my eyes badly taints the survey. It seems pretty difficult to find people who only smoke marijuana and not cigarettes, as I only know of maybe 1, 2 other people tops, excluding myself.

Still, the data from the survey does not sound paticularily scary- I KNOW coffee rots your teeth out and you dont see any congressional BS about that.

Still, any thoughts?