Effects of Marihuana on Man

Abstract

The Committee on Drugs has reviewed the pharmacology of marihuana with special emphasis on effects in man because of the enormous impact of this drug on society. Much of modern day society's reaction to and attitudes about this psychoactive agent does not reflect its pharmacology, and it is only recently that pertinent biologic facts about marihuana have become known. The Committee reports these facts here, in part, to inform the Academy membership of these facts and, in part, to provide a perspective with which to consider the various societal controls (i.e., laws) on the use of marihuana. COMPOSITION Marihuana is a mixture of leaves and flowering tops of the plant Cannabis sativa L. It contains approximately 1% Δ-9-tetrahydrocannabinol (THC), the principal psychoactive substance in marihuana. Street preparations tend to vary in Δ-9-THC content; the range is 0% to 5%. An average marihuana cigarette contains 500 mg of marihuana and, therefore, about 5 mg of Δ-9-THC. Hashish, usually used in Eastern (Asiatic) countries and in North Africa, is the resinous substance of the flowers and leaves of Cannabis sativa L in which Δ-9-THC is found. Hashish contains 5% to 15% Δ-9-THC and is usually smoked as a mixture of the resin and tobacco. Generally, marihuana cigarettes do not contain tobacco, although some street preparations do. USERS In considering adverse effects of marihuana, it is important to appreciate some pertinent epidemiologic facts. It is estimated that 24,000,000 Americans have tried marihuana at least once and that there are 8,300,000 current users in this country.1 Approximately 70% of adults and youth (12 through 17 years) who were found by the National Commission on Marihuana and Drug Abuse1 to use marthuana used it so infrequently as to be considered experimental users.