Reefer Madness: Part I

The Plant in Question

"MARIJUANA" is the Mexican colloquial name for a plant known to botanists as Cannabis sativa. In various forms it has long been familiar throughout the world: in Africa as "dagga," in China as "ma," in Northern Europe as "hemp." Although cannabis most likely originated in the steppes of central Asia, it now thrives in almost any climate, spreading like milkweed or thistle, crowding out neighboring grasses and reaching heights of three to twenty feet at maturity. Marijuana has been cultivated for at least 5,000 years; it is one of the oldest agricultural commodities not grown for food. The stalks of the plant contain fibers that have been woven for millennia to make rope, canvas, and paper. Cannabis is dioecious, spawning male and female plants in equal proportion. The flowering buds of the female -- and to a lesser extent those of the male -- secrete a sticky yellow resin rich with cannabinoids. the more than sixty compounds unique to marijuana. Several of them are psychoactive, most prominently delta-9-tetrahydrocannabinol (THC).

Lester Grinspoon, an associate professor of psychiatry at Harvard Medical School, believes that marijuana will someday be hailed as a "miracle drug," one that is safe, inexpensive, and versatile. In his book Marihuana, the Forbidden Medicine (1993) Grinspoon provides anecdotal evidence that smoking marijuana can relieve the nausea associated with chemotherapy, prevent blindness induced by glaucoma, serve as an appetite stimulant for AIDS patients, act as an anti-epileptic, ward off asthma attacks and migraine headaches, alleviate chronic pain, and reduce the muscle spasticity that accompanies multiple sclerosis, cerebral palsy, and paraplegia. Other doctors think that Grinspoon is wildly optimistic, and that no "crude drug" like marijuana -- composed of more than 400 chemicals -- should be included in the modern pharmacopoeia. They point out that effective synthetic drugs, of precise dosage and purity, have been developed for every one of marijuana's potential uses. Dronabinol, a synthetic form of delta-9-THC, has been available for years, though some clinical oncologists find it inferior to marijuana as an anti-nausea agent. There have been remarkably few large-scale studies that might verify or disprove Grinspoon's claims. Nevertheless, thirty-six states allow the medicinal use of marijuana. And eight patients are currently receiving it from the Public Health Service. According to Grinspoon, the federal government has always been far more interested in establishing marijuana's harmful effects than in discovering any of its benefits, while major drug companies have little incentive to fund expensive research on marijuana. As Grinspoon explains. "You cannot patent this plant."

The long-term health effects of chronic marijuana use, and marijuana's role as a "gateway" to the use of other illegal drugs, are issues surrounded by great controversy. Marijuana does not create a physical dependence in its users, but it does create a psychological dependence in some. People who smoke marijuana are far more likely to experiment later with other psychoactive drugs, but no direct cause-and-effect relationship has ever been established. Delta-9-THC is highly lipid-soluble and has a half-life of five days, which means that it diffuses widely throughout the human body and remains there for quite some time: an occasional user can fail a urine test three days after smoking a single joint, and a heavy user may test positive after abstaining from marijuana for more than a month. Delta-9-THC's persistence within various cells and vital organs (also a characteristic of Valium, Thorazine, and quinine) suggests that it could have the ability to exert subtly harmful effects; few have yet been proved. Studies of lifelong heavy marijuana users in Jamaica, Greece, and Costa Rica reveal little psychological or physiological damage. Much more research however, needs to be done in the areas of cognition, reproduction, and immunology. Adolescent users in particular would be at risk if marijuana were found to have pernicious systemic effects. Some studies have shown that short-term memory deficiencies in heavy smokers, though reversible, may endure long after the cessation of marijuana use. Other studies have demonstrated in vitro and in laboratory animals that marijuana may have a mild immunosuppressive effect, but no study has conclusively linked delta-9-THC to immune-system changes in human beings. Well-publicized horror stories from the 1970s -- that marijuana kills brain cells, damages chromosomes and prompts men to grow breasts -- were based on faulty research.

Smoking marijuana does seem to damage the pulmonary system, in some of the ways that inhaling tobacco smoke does. In a study of people who have smoked four or five joints a day for more than ten years, the physician Donald P. Tashkin, of the University of California at Los Angeles Medical Center, has found substantial evidence that marijuana smoke can cause chronic bronchitis, changes in cells of the central airway which are potentially pre-cancerous, and an impairment in scavenger-cell function which could lead to a greater risk of respiratory infection. A joint seems to deliver four times as much carcinogenic tar as a tobacco cigarette of the same size. Tashkin expects that some heavy marijuana users will eventually suffer cancers of the mouth, throat, and lungs, although none of his research subjects has yet developed a malignancy. Oddly enough, the more potent strains of marijuana may prove less dangerous, since less of them needs to be smoked.

There is much less disagreement about short term health effects of marijuana. According to the physician Leo Hollister, a former president of the American College of Neuropsychopharmacology, who now teaches at the University of Texas, the occasional use of marijuana by a healthy adult poses no greater risks than the moderate consumption of alcohol. For a variety of reasons, however, marijuana should not be smoked by schizophrenics, pregnant women, and people with heart conditions. Although the misuse of over-the-counter medications such as aspirin, acetaminophen, and antihistamines each year kills hundreds of Americans, not a single death has ever been credibly attributed directly to smoking or consuming marijuana in the 5,000 years of the plant's recorded use. Marijuana is one of the few therapeutically active substances known for which there is no well defined fatal dose. It has been estimated that a person would have to smoke a hundred pounds of marijuana a minute for fifteen minutes in order to induce a lethal response.