The Merck Manual is one of the most widely used and respected medical texts in the world. Like the medical journal articles cited in this petition, its contents are subject to peer review prior to publication. The complete section on “Dependence of the Cannabis (Marijuana) Type” from the 15th edition of the Merck Manual of Diagnosis and Therapy is as follows:
“Chronic or periodic administration of cannabis or cannabis substances producing some psychic dependence because of the desired subjective effects, but no physical dependence; there is no abstinence syndrome when the drug is discontinued. Cannabis can be used on an episodic but continuous basis without evidence of social or psychic dysfunction. In many users the term dependence with its obvious connotations probably is misapplied.
“Use of the drug is widespread. In the USA it is commonly used in the form of cigarettes made from the dried plant, Cannabis sativa, or as hashish, the pressed resin of the plant. Recently, synthetic D-9 tetrahydrocannabinol (THC), an active constituent of marijuana, has become available for research and limited clinical use; despite claims of dealers and users, it does not appear on the street.
“Symptoms and signs: Cannabis produces a dreamy state of consciousness in which ideas seem disconnected, uncontrollable, and freely flowing. Time, color, and spatial perceptions are distorted and enhanced. In general, there is a feeling of well-being, exaltation, excitement, and inner joyousness that has been termed a “high.” Many of the psychological effects seem to be related to the setting in which the drug is taken. An occasional panic reaction has occurred, particularly in naive users, but these have become unusual as the culture has gained increasingly familiarity with the drug. Communicative and motor abilities are decreased during the use of these drugs. Difficulty in depth perception and altered sense of timing, both of which are particularly hazardous during automobile driving, have been demonstrated. There are now several published reports on the exacerbation of schizophrenic symptoms by marijuana even in patients being treated with antipsychotic medication (e.g., chlorpromazine).
“Metabolic products of marijuana are retained in the tissues for a lengthy time. Lowered testosterone levels have been reported, although the biologic significance of this is uncertain.
“In recent years, critics of marijuana use have become prominent and have enlisted much scientific data in support. A counter-reform movement opposed to decriminalization and the easy acceptance of the drug in American society has emerged. Many of the claims regarding severe biologic impact are still uncertain, but some other points are not. Despite the acceptance of the “new” dangers of marijuana, there is still little evidence of biologic damage even among relatively heavy users. This is true even in the areas intensively investigated, such as pulmonary, immunologic, and reproductive function. The surveys that continually showed an increased prevalence and increasing daily use by high school students have in recent years shown a diminution of use. [This trend has reversed itself in the early 1990’s]
“Marijuana used in the USA has a higher THC content that in the past. Many critics have incorporated this fact into warnings, but the chief opposition to the drug rests on a moral and political, and not a toxicologic, foundation.”(4)