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The Toxicity of Recreational Drugs

Alcohol is more lethal than many other commonly abused substances

Robert Gable

Other Ways to Invite Death

Ranking psychoactive substances...Click to Enlarge Image

A simpleminded look at the ratio of effective to lethal doses ignores many complications, some of which are well recognized, some rather subtle. Take, for example, the fact that danger generally increases with repetitive consumption. High blood levels of a drug, without rest periods between use, tend to heighten risk, because the affected organs do not have sufficient time to recover. Studies of MDMA use, for example, show that relatively small repeated doses result in disproportionately large increases of MDMA in blood plasma. Cocaine is the substance that induces the highest rate of repetitive consumption as a result of mood change. Heroin and alcohol come in second and third. Also, the tendency of a user to take a "booster" dose prematurely is greater with substances that require an hour or more to provide the full psychological effect—during the interim the user often assumes that the original dose was not sufficiently potent. This phenomenon routinely occurs with dextromethorphan (found in cough medicines), GHB and MDMA.

Overdose quantities that are based on acute toxicity also do not take into account the probability that an individual will become addicted. This probability can be cast as a drug's capture ratio: Of the people who sample a particular substance, what portion will become physiologically or psychologically dependent on the drug for some period of time? Heroin and methamphetamine are the most addictive by this measure. Cocaine, pentobarbital (a fast-acting sedative), nicotine and alcohol are next, followed by marijuana and possibly caffeine. Some hallucinogens—notably LSD, mescaline and psilocybin—have little or no potential for creating dependence.

Finally, a comparison of overdose fatalities does not take into account cognitive impairments and risky or aggressive behaviors that sometimes follow drug use. And as most people are well aware, a substantial proportion of violent confrontations, rapes, suicides, automobile accidents and AIDS-related illnesses are linked to alcohol intoxication.

Despite the health risks and social costs, consciousness-altering chemicals have been used for centuries in almost all cultures. So it would be unrealistic to expect that all types of recreational drug use will suddenly cease. Self-management of these substances is extremely difficult, yet modern Western societies have not, in general, developed positive, socially sanctioned rituals as a means of regulating the use of some of the less hazardous recreational drugs. I would argue that we need to do that. The science of toxicology may provide one step in that direction, by helping to teach members of our society what a lot of tribal people already know.

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