The Toxicity of Recreational Drugs
Alcohol is more lethal than many other commonly abused substances
Robert S. Gable
The Shuar tribes in Ecuador have for centuries used native plants to induce religious intoxication and to discipline recalcitrant children. By comparison, most North Americans know little about the mood-altering potential of the wild vegetation around them. And those who think they know something on this subject are often dangerously ignorant. Over a three-week period in 1983, for example, 22 Marines wanting to get high were hospitalized because they ate too many seeds of the jimsonweed plant (Datura stramonium), which they found growing wild near their base, Camp Pendleton in southern California.
The easier way to learn about the relation between the quantity of a substance taken and the resulting level of physiological impairment is through careful laboratory study. The first example of such an exercise, in 1927, used rodents. Research toxicologist John Trevan published an influential paper that reported the use of more than 900 mice to assess the lethality of, among other things, cocaine. As he and others have since found, a substance that is tolerated or even beneficial in small quantities often has harmful effects at higher levels. The amount of a substance that produces a beneficial effect in 50 percent of a group of animals is called the median effective dose. The quantity that produces mortality in 50 percent of a group of animals is termed the median lethal dose.
Laboratory tests with animals can give a general picture of the potency of a substance, but generalizing experimental results from, say, mice to humans is always suspect. Thus toxicologists also use two other sources of information. The first is survey data collected from poison-control centers, hospital emergency departments and coroners' offices. Another consists of published clinical and forensic reports of fatalities or near-fatalities.
But these sources, like animal studies, have their limitations. Simply tallying the number of people who die or who show up at emergency rooms is, by itself, meaningless because the number of such incidents will be influenced by the total number of people using a particular substance, something that is impossible to know. For example, atropine is more toxic than alcohol, but more deaths will be reported for alcohol than for atropine because so many more people get drunk than ingest jimsonweed. Furthermore, most overdose fatalities involve the use of two or more substances (usually including alcohol), situations for which the overall toxicity is largely unknown. In short: When psychoactive substances are combined, all bets are off.
How then does one gauge the relative risks of different recreational drugs? One way is to consider the ratio of effective dose to lethal dose. For example, a normally healthy 70-kilogram (154-pound) adult can achieve a relaxed affability from approximately 33 grams of ethyl alcohol. This effective dose can come from two 12-ounce beers, two 5-ounce glasses of wine or two 1.5-ounce shots of 80-proof vodka. The median lethal dose for such an adult is approximately 330 grams, the quantity contained in about 20 shots of vodka. A person who consumes that much (10 times the median effective dose), taken within a few minutes on an empty stomach, risks a lethal reaction. And plenty of people have died this way.
As far as toxicity goes, such deaths are quite telling. Indeed, autopsy reports from cases of fatal overdose (whether from alcohol or some other substance) provide key information linking death and drug consumption. ...
The most toxic recreational drugs, such as GHB (gamma-hydroxybutyrate) and heroin, have a lethal dose less than 10 times their typical effective dose. The largest cluster of substances has a lethal dose that is 10 to 20 times the effective dose: These include cocaine, MDMA (methylenedioxymethamphetamine, often called "ecstasy") and alcohol. A less toxic group of substances, requiring 20 to 80 times the effective dose to cause death, include Rohypnol (flunitrazepam or "roofies") and mescaline (peyote cactus). The least physiologically toxic substances, those requiring 100 to 1,000 times the effective dose to cause death, include psilocybin mushrooms and marijuana, when ingested. I've found no published cases in the English language that document deaths from smoked marijuana, so the actual lethal dose is a mystery. My surmise is that smoking marijuana is more risky than eating it but still safer than getting drunk.
Alcohol thus ranks at the dangerous end of the toxicity spectrum. So despite the fact that about 75 percent of all adults in the United States enjoy an occasional drink, it must be remembered that alcohol is quite toxic. Indeed, if alcohol were a newly formulated beverage, its high toxicity and addiction potential would surely prevent it from being marketed as a food or drug. This conclusion runs counter to the common view that one's own use of alcohol is harmless. That mistaken impression arises for several reasons....
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.
Ranking psychoactive substances by their ratios of lethal dose to effective dose gives a general picture of how likely each is to precipitate an acute fatal reaction. By this measure, many illicit drugs are considerably safer than alcohol.
See table below.