A new study in The Lancet rates the harmfulness of 20 psychoactive drugs according to 16 criteria and finds that alcohol comes out on top. Although that conclusion is generating headlines, it is not at all surprising, since alcohol is, by several important measures (including acute toxicity, impairment of driving ability, and the long-term health effects of heavy use), the most dangerous widely used intoxicant, and its abuse is also associated with violence, family breakdown, and social estrangement. A group of British drug experts gathered by the Independent Scientific Committee on Drugs (ISCD) rated alcohol higher than most or all of the other drugs for health damage, mortality, impairment of mental functioning, accidental injury, economic cost, loss of relationships, and negative impact on community. Over all, alcohol rated 72 points on a 100-point scale, compared to 55 for heroin, 54 for crack cocaine, and 33 for methamphetamine. Cannabis got a middling score of 20, while MDMA (Ecstasy), LSD, and psilocybin mushrooms were at the low end, with ratings of 9, 7, and 6, respectively.

One can quibble with these judgments (some of that in a minute). But there is no question that the ISCD, which University of Bristol psychopharmacologist David Nutt organized after he was fired from his job as the government's chief drug adviser for excessively candid comparisons of cannabis and alcohol, has put more thought into its classification scheme that the British and U.S. governments put into theirs. As Leslie King, a co-author of the study, wryly observes, "What governments decide is illegal is not always based on science."

You could view the fact that distinctions between tolerated and proscribed drugs have never had a firm scientific basis as yet another reason why politicians should not be empowered to control the substances we put into our bodies. Or, if you are David Nutt, you could view it as a reason why they should consult experts like you before they try to do so. While Nutt seems to think that marijuana and psychedelics are too strictly controlled, for example, he also argues that alcoholic beverages are too cheap and too readily available. For him, that conclusion flows directly from the scientific evidence, although a closer examination might reveal some intervening value judgments.

Putting aside the issue of technocratic paternalism, there is an impressionistic aspect to many of the judgments underlying these drug scores. In the procedure used for the study, the authors write, "scores are often changed from those originally suggested as participants share their different experiences and revise their views." Sometimes these views are backed up by data, such as ratios of lethal to effective doses or survey results that indicate addiction rates, but often the evidence is more anecdotal. It also is not clear whether judgments about alcohol's harms were influenced by the fact that it is so widely consumed. As I read the study, the scores are supposed to be independent of use rates. But A.P. reports that "experts said alcohol scored so high because it is so widely used and has devastating consequences not only for drinkers but for those around them." Regarding social consequences, there is much room for interpretation about alcohol's causal role in domestic violence and other harmful behavior.

The scores may also exaggerate the intrinsic dangers of illegal drugs, since they do not distinguish between harms caused by drug use itself and harms caused by prohibition. "Many of the harms of drugs are affected by their availability and legal status," the authors note. "Ideally, a model needs to distinguish between the harms resulting directly from drug use and those resulting from the control system for that drug." The harm associated with heroin use, for example, is compounded by unpredictable purity, by artificially high prices that encourage injection, and by anti-paraphernalia policies that encourage needle sharing.

As usual, defenders of drinking are outraged by the comparison between alcohol and illegal drugs. Brigid Simmonds, chief executive of the British Beer & Pub Association, tells The Sun, "The vast majority of people know it's just not rational to say that enjoying a social beer with friends in the pub or glass of wine over dinner has the moral or societal equivalence of injecting heroin or smoking a crack pipe." Such reactions are based on the observation that the vast majority of drinkers are not alcoholics. Despite alcohol's very real dangers, they generally manage to consume it in a way that not only does not harm them or others but on balance enhances their lives. Here is the point that defensive drinkers like Simmonds miss: If this is possible with alcohol, it is possible with any intoxicant that large numbers of people have shown an interest in consuming. For more on that, see my book Saying Yes.

I discuss Nutt's drug-related deviance here, here, and here. Ron Bailey notes a previous Nutt-led study of drug dangers here. Brendan O'Neill cited Nutt in his 2009 attack on the "unholy alliance between alcohol prohibitionists and marijuana reformers." I discussed the potential and perils of comparing marijuana to alcohol in a 2010 book review.

[Thanks to Terry Michael for the tip.]