C. sativa grows as a common weed in many parts of the world, and drug preparations vary widely in potency according to climate, cultivation, and method of preparation. Mexico, Paraguay, and the United States are the top marijuana-producing nations worldwide. C. indica is a shorter, hardier variety with rounded blue-green leaves, grown in Afghanistan for hashish. Most marijuanas grown in the United States since the late 1980s are hybrids of the two and yield a much more potent product than the marijuana of the past. The resin found on flower clusters and top leaves of the female plant is the most potent drug source and is used to prepare hashish, the highest grade of cannabis. The bud of the female plant, called sinsemilla, is the part most often smoked as marijuana.
The effects of marijuana vary with its strength and dosage and with the state of mind of the user. Typically, small doses result in a feeling of well-being. The intoxication lasts two to three hours, but accompanying effects on motor control last much longer. High doses can cause tachycardia, paranoia, and delusions. Although it produces some of the same effects as hallucinogens like LSD and mescaline (heightened sensitivity to colors, shapes, music, and other stimuli and distortion of the sense of time), marijuana differs chemically and pharmacologically.
The primary active component of marijuana is delta-9-tetrahydrocannabinol (THC), although other cannabinol derivatives are also thought to be intoxicating. In 1988 scientists discovered receptors that bind THC on the membranes of nerve cells. They reasoned that the body must make its own THC-like substance. The substance, named anandamide, was isolated from pig brains in 1992 by an American pharmacologist, William A. Devane.
Marijuana lowers testosterone levels and sperm counts in men and raises testosterone levels in women. In pregnant women it affects the fetus and results in developmental difficulties in the child. There is evidence that marijuana affects normal maturation of preadolescent and adolescent users and that it affects short-term memory and comprehension. Heavy smokers often sustain lung damage from the smoke and contaminants. Regular use can result in dependence.
With the increase in the number of middle-class users in the 1960s and 1970s, there came a somewhat greater acceptance of the view that marijuana should not be considered in the same class as narcotics and that U.S. marijuana laws should be relaxed. The Drug Abuse Prevention Act of 1970 eased federal penalties somewhat, and 11 states decriminalized possession. However, in the late 1980s most states rewrote their drug laws and imposed stricter penalties. Opponents of easing marijuana laws have asserted that it is an intoxicant less controllable than alcohol, that our drug-using society does not need another widely used intoxicant, and that the United States should not act to weaken UN policies, which are opposed to the use of marijuana for other than possible medical purposes.
Controversy surrounds the medical use of marijuana, with proponents saying it is useful for treating pain and the nausea and vomiting that are side effects of cancer chemotherapy and for restoring the appetite in people with AIDS. Although its active ingredient, THC (synthesized in 1966 and approved by the U.S. Food and Drug Administration in 1985) is available by prescription in pill form, proponents say it is not as effective as the herb and is more expensive. A 1999 U.S.-government-sponsored study by the Institute of Medicine found that marijuana appeared beneficial for certain medical conditions, such as nausea caused by chemotherapy and wasting caused by AIDS. Because of the toxicity of marijuana smoke, however, it was hoped that further research might lead to development of new delivery systems, such as bronchial inhalers.
The Office of National Drug Control Policy has opposed legalization of the medical use of marijuana, citing law enforcement issues and the possibility that some would use it as a pretext to sell marijuana for nonmedical use, and the FDA said in 2006 that, despite the 1999 report, that marijuana "has no accepted or proven use in the United States." Proponents, disregarding the law, have set up networks for the distribution of the drug to people who they judge will be helped by it and continue to lobby for its legalization for medical use. More than a dozen U.S. states permit the use of marijuana for medical reasons, but, as a result of a Supreme Court ruling in 2005, this does not protect medical users with a prescription from federal prosecution. However, in 2009, Attorney General Eric Holder ordered that federal prosecutors not focus on persons who clearly comply with state medical marijuana laws. Another, lower court ruling permits doctors to discuss medical use of marijuana with their patients but forbids them to help patients obtain the drug. A number of countries, including Canada, permit the medicinal use of the drug.
Marijuana has been used as an agent for achieving euphoria since ancient times; it was described in a Chinese medical compendium traditionally considered to date from 2737 B.C. Its use spread from China to India and then to N Africa and reached Europe at least as early as A.D. 500. A major crop in colonial North America, marijuana (hemp) was grown as a source of fiber. It was extensively cultivated during World War II, when Asian sources of hemp were cut off.
Marijuana was listed in the United States Pharmacopeia from 1850 until 1942 and was prescribed for various conditions including labor pains, nausea, and rheumatism. Its use as an intoxicant was also commonplace from the 1850s to the 1930s. A campaign conducted in the 1930s by the U.S. Federal Bureau of Narcotics (now the Bureau of Narcotics and Dangerous Drugs) sought to portray marijuana as a powerful, addicting substance that would lead users into narcotics addiction. It is still considered a "gateway" drug by some authorities. In the 1950s it was an accessory of the beat generation; in the 1960s it was used by college students and "hippies" and became a symbol of rebellion against authority.
The Controlled Substances Act of 1970 classified marijuana along with heroin and LSD as a Schedule I drug, i.e., having the relatively highest abuse potential and no accepted medical use. Most marijuana at that time came from Mexico, but in 1975 the Mexican government agreed to eradicate the crop by spraying it with the herbicide paraquat, raising fears of toxic side effects. Colombia then became the main supplier. The "zero tolerance" climate of the Reagan and Bush administrations (1981-93) resulted in passage of strict laws and mandatory sentences for possession of marijuana and in heightened vigilance against smuggling at the southern borders. The "war on drugs" thus brought with it a shift from reliance on imported supplies to domestic cultivation (particularly in Hawaii and California). Beginning in 1982 the Drug Enforcement Administration turned increased attention to marijuana farms in the United States, and there was a shift to the indoor growing of plants specially developed for small size and high yield. After over a decade of decreasing use, marijuana smoking began an upward trend once more in the early 1990s, especially among teenagers, but by the end of the decade this upswing had leveled off well below former peaks of use.
See J. S. Hochman, Marijuana and Social Evolution (1972); E. Marshal, Legalization (1988); M. S. Gold, Marijuana (1989); L. Grinspoon and B. J. Bakalar, Marijuana: The Forbidden Medicine (1995); publications of the Drugs & Crime Data Center and Clearinghouse, the Bureau of Justice Statistics Clearinghouse, and the National Clearinghouse for Alcohol and Drug Information.