Quite simply, last year, alcohol killed 50,000 people. That's not from accidents, that's just from consumption. So, alcohol kills about 50,000 a year, give or take a few thousand. One of my favorite stats on the weed issue is that in human history, not one human has ever overdosed and died from weed. Ever. One would have to smoke about 25,000 joints in 15 minutes to get a toxic level of THC. Translation: pretty impossible.
Alcohol seems way more toxic than marijuana is. Alcohol damages brain cells, encourages people to act like idiots, can cause all kinds of kidney and liver problems, the list goes on and on. Marijuana only has long term effects if the person is a daily user of it and the short term just gives the person a high.