this study. I know nothing about the researchers, how they were funded, or what other biases they might have. What they've attempted to do is to quantify the harm done by various commonly-used drugs (including alcohol and tobacco). They've attempted to separately measure harm to the using individual and harm to society.
The chart at right (click to enlarge) shows the various drugs ranked by harm to the user (most harmful first). Alcohol tops the rankings both by harm to users and to society.
First question that occurs to me: is the overall “harm score” normalized to per capita, or is it an aggregate score? If the latter, then alcohol's position at the top is hardly surprising. If the former, then these results are certainly surprising to me!
This study's results support the position of many drug legalization advocates (including me): the drugs prohibited today aren't any more harmful than the perfectly legal alcohol and tobacco. The illegal drugs have been demonized, much as alcohol was before Prohibition...