In this list of the top 10 mechanisms that decrease human lifespan, tobacco is #4 at 50 million lost years of life per year and alcohol is #8 at 30 million lost years per year.
http://www.sciencemag.org/cgi/content/full/319/5862/424/F1
For those who can’t access it,
1. Childhood and maternal malnutrition 200 million
2. High BP, cholesterol, inactivity 150 million
3. Unsafe sex 80 million
4. Tobacco 50 million
5. Unsafe water 50 million
6. War and revolution 40 million
7. Indoor smoke, indoor solid fuel use 35 million
8. Alcohol 30 million
9. Urban air pollution 6 million
10. Climate change 5 million
Shouldn't #5 be higher up on the list. That's most of the WORLD. Heck, many places in the US have unsafe water.