The jury is still very much out on this one. There is a lot of evidence that it can, and a lot that it doesn't. It's way too early to be drawing conclusions about this.
Frankly when I hear most people talking about pot these days it sounds an awful lot like people used to sound way back when cigs were considered absolutely fine and sometimes an actual health benefit. I will not be surprised at all if, in 20-30 years' time people look back at pot-smoking and wondered how it was ever legalised or done at all and that there are all sorts of negative side-effects that will be discovered. I mean you're burning something and inhaling it - common sense should tell you that this should come with some negative side-effects, even if it does have some benefits for some people in some cases.
As a personal side note: I've known a lot of pot-smokers over the years and the vast majority of them ended up wasting their school and uni life away in a cloud of smoke and ended up with bad grades or having to repeat years. I think a few went on to do good things and got good jobs but most didn't. So the issue here isn't just biological/physiological health - it's social health and well-being, too.
Mate theres never been a proven death as a result of cannabis.
People are already burning tobacco and smoking it with the added substance of nicotine which is the most dangerous substance that is currently legal.
And Alcohol is even worse, how many people does it kill, how many car accidents does it cause, how many phone calls to the police does alcohol cause, how many hospital patients are in there because of alcohol? How many of these things that i have listed can be accosiated to cannabis. None with the exception of car accidents maybe but you have to be stupid to drive and smoke in the first place because when your high you still have your inhabitions and common sense unlike alcohol.