Sunday, March 25, 2007
Comparative Drug Harms
The Lancet recently published an article ranking twenty drugs, legal and illegal, according to their potential for harm. (The article is here, though a free registration is required.) They had groups of experts score each of the substances along nine dimensions of harm, on a four-point scale, from 'zero' representing no risk to 'three' representing extreme risk. The dimensions comprised three categories: physical harm (acute, chronic, intravenous); dependence (intensity of pleasure, psychological, physical); and social harm (intoxication, health-care costs, other). The nine individual scores were averaged for the overall assessment, which ranked heroin as the most harmful drug. Cocaine was second, alcohol fifth, tobacco ninth, cannabis eleventh, LSD fourteenth, ecstasy eighteenth, and the least harmful of the twenty ranked drugs was Vice Squad fetish khat. The authors note that their ranking does not cohere with the scheduling of drugs that is the basis for drug policy and enforcement.
The harms of drugs, of course, are dependent upon the public policies that are adopted towards them. The authors note as much when they caution against direct comparisons in their rankings between the legal alcohol and tobacco and the illegal drugs. But I think that this point could be further stressed. The Swiss experiment with heroin maintenance (along with subsequent heroin maintenance trials) shows that even with that drug, harms can greatly be reduced through easy availability of a standardized dose in a controlled setting. Dependence responds to policy, too; for instance, a prohibition that renders availability sporadic and purity uncertain lends a gambling element to drug acquisition that itself can be addictive for some users. Nevertheless, rankings such as the one in The Lancet can be helpful in highlighting the inordinately repressive control regime that has been adopted towards marijuana, hallucinogens, ecstasy, and, in the United States (though not in Britain), khat.