I'm a big proponent of legalizing marijuana. I know it is much less dangerous than cigarettes and alcohol. But just as I know that marijuana is not a "gateway drug" that will lead you down the path toward junkie-hood, I also know it is not entirely 100% safe. Hell, breakfast cereal isn't 100% safe, you could choke on your cornflakes, aspirate milk, and die.
While it isn't as addictive as nicotine (really, not much is), marijuana can be addictive. ANYTHING can be addictive mentally, but I also know of people experiencing uncomfortable withdrawal symptoms after heavy bouts of weed smoking, so obviously it has the potential to be physically addictive as well. Then again, so does sugar, corn syrup, chocolate, coffee, etc. It is unlikely that weed smoking will lead to addiction, but that doesn't mean it is totally non-addictive.
Marijuana can also kill people. The more I see posts about how wonderful and safe weed is, the more pissed off I get. I AM ALLERGIC TO MARIJUANA. It has the potential to kill me, by inducing a fatal asthma attack (and that is even if I don't smoke it; eating marijuana has the same effects), so it is reasonable to assume that somewhere, someone has died from using marijuana. So I trolled around the Internet to pull up some stuff.
Trebobslab -- a nice retraction statement from someone who also initially claimed that weed was 100% safe
PDF file from DrugWatch Intl -- their 2002 report shows 157 reported deaths 31 metropolitan areas combined. Now that number is really low, but it isn't zero. Only 2 deaths were considered overdose (and you would have to ingest a heck of a lot; it is probably impossible to overdose on THC through smoking it). The other deaths were linked by suicide, accident, other, etc. These are single-drug reportings, there has not been a comprehensive study on how dangerous marijuana might be in combination with other drugs, with the exception of weed and cigarettes.
Cigarette smoking leads to cancer, fact.
Weed smoking does NOT lead to cancer, fact. In fact, lung cancer is actually reduced in folks who only smoke weed.
However, folks who smoke both weed and cigarettes are EIGHT TIMES more likely to get cancer than folks who just smoke cigarettes. Try putting that in your pipe and smoking it.
Pro/Con Debate - Can Marijuana Use Cause Death?
Wiki: How many people die each year from marijuana?
So it's still pretty low... unless you smoke and drive.
Smoking Marijuana Doubles Risk of Fatal Accidents
And that was just a ten-minute search. Look, weed is pretty safe compared to a host of things out there, it is probably safer than the pesticides they spray on our food, but that doesn't mean it is the be-all end-all wonder drug of our times. Heck, that's what cocaine used to be back at the turn of the previous century.
I am happy to accept the legalization of weed for adults (18+) under reasonable restrictions, even as I know it isn't totally safe and that I can never smoke it. Nothing in life is totally safe or guaranteed, and we need to stop acting like children who must cram every argument into the box of 'black' or 'white' rather than rationally reviewing all of the data (not hiding it) and coming out to the correct shade of grey. This is true of weed, this is true of business, and this is true of politics. Until we stop the attitude of "I'm Right/You're Wrong" our society is never going to improve because someone will always be the "Winner" and someone else will always resent that. We have got to stop creating sides to every argument; instead, come together and reach an acceptable compromise so we can ALL be winners.