MYTH: marijuana'S HARMS HAVE BEEN PROVED SCIENTIFICALLY. In the 1960s and 1970s, many people believed that marijuana was harmless. Today we know that marijuana is much more dangerous than previously believed.
FACT: In 1972, after reviewing the scientific evidence, the National Commission on Marihuana and Drug Abuse concluded that while marijuana was not entirely safe, its dangers had been grossly overstated. Since then, researchers have conducted thousands of studies of humans, animals, and cell cultures. None reveal any findings dramatically different from those described by the National Commission in 1972. In 1995, based on thirty years of scientific research editors of the British medical journal Lancet concluded that "the smoking of cannabis, even long term, is not harmful to health."
MYTH: marijuana HAS NO MEDICINAL VALUE. Safer, more effective drugs are available. They include a synthetic version of THC, marijuana's primary active ingredient, which is marketed in the United States under the name Marinol.
FACT: marijuana has been shown to be effective in reducing the nausea induced by cancer chemotherapy, stimulating appetite in AIDS patients, and reducing intraocular pressure in people with glaucoma. There is also appreciable evidence that marijuana reduces muscle spasticity in patients with neurological disorders. A synthetic capsule is available by prescription, but it is not as effective as smoked marijuana for many patients. Pure THC may also produce more unpleasant psychoactive side effects than smoked marijuana. Many people use marijuana as a medicine today, despite its illegality. In doing so, they risk arrest and imprisonment.
MYTH: marijuana IS HIGHLY ADDICTIVE. Long term marijuana users experience physical dependence and withdrawal, and often need professional drug treatment to break their marijuana habits.
FACT: Most people who smoke marijuana smoke it only occasionally. A small minority of Americans - less than 1 percent - smoke marijuana on a daily basis. An even smaller minority develop a dependence on marijuana. Some people who smoke marijuana heavily and frequently stop without difficulty. Others seek help from drug treatment professionals. marijuana does not cause physical dependence. If people experience withdrawal symptoms at all, they are remarkably mild.
MYTH: marijuana IS A GATEWAY DRUG. Even if marijuana itself causes minimal harm, it is a dangerous substance because it leads to the use of "harder drugs" like heroin, LSD, and cocaine.
FACT: marijuana does not cause people to use hard drugs. What the gateway theory presents as a causal explanation is a statistic association between common and uncommon drugs, an association that changes over time as different drugs increase and decrease in prevalence. marijuana is the most popular illegal drug in the United States today. Therefore, people who have used less popular drugs such as heroin, cocaine, and LSD, are likely to have also used marijuana. Most marijuana users never use any other illegal drug. Indeed, for the large majority of people, marijuana is a terminus rather than a gateway drug.
MYTH: marijuana KILLS BRAIN CELLS. Used over time, marijuana permanently alters brain structure and function, causing memory loss, cognitive impairment, personality deterioration, and reduced productivity.
FACT: None of the medical tests currently used to detect brain damage in humans have found harm from marijuana, even from long term high-dose use. An early study reported brain damage in rhesus monkeys after six months exposure to high concentrations of marijuana smoke. In a recent, more carefully conducted study, researchers found no evidence of brain abnormality in monkeys that were forced to inhale the equivalent of four to five marijuana cigarettes every day for a year. The claim that marijuana kills brain cells is based on a speculative report dating back a quarter of a century that has never been supported by any scientific study.
MYTH: marijuana CAUSES CRIME. marijuana users commit more property offenses than nonusers. Under the influence of marijuana, people become irrational, aggressive, and violent.
FACT: Every serious scholar and government commission examining the relationship between marijuana use and crime has reached the same conclusion: marijuana does not cause crime. The vast majority of marijuana users do not commit crimes other than the crime of possessing marijuana. Among marijuana users who do commit crimes, marijuana plays no causal role. Almost all human and animal studies show that marijuana decreases rather than increases aggression.
MYTH: marijuana INTERFERES WITH MALE AND FEMALE SEX HORMONES. In both men and women, marijuana can cause infertility. marijuana retards sexual development in adolescents. It produces feminine characteristics in males and masculine characteristics in females.
FACT: There is no evidence that marijuana causes infertility in men or women. In animal studies, high doses of THC diminish the production of some sex hormones and can impair reproduction. However, most studies of humans have found that marijuana has no impact of sex hormones. In those studies showing an impact, it is modest, temporary, and of no apparent consequence for reproduction. There is no scientific evidence that marijuana delays adolescent sexual development, has feminizing effect on males, or a masculinizing effect on females.
MYTH: marijuana IS MORE DAMAGING TO THE LUNGS THAN TOBACCO. marijuana smokers are at a high risk of developing lung cancer, bronchitis, and emphysema.
FACT: Moderate smoking of marijuana appears to pose minimal danger to the lungs. Like tobacco smoke, marijuana smoke contains a number of irritants and carcinogens. But marijuana users typically smoke much less often than tobacco smokers, and over time, inhale much less smoke. As a result, the risk of serious lung damage should be lower in marijuana smokers. There have been no reports of lung cancer related solely to marijuana. However, because researchers have found precancerous changes in cells taken from the lungs of heavy marijuana smokers, the possibility of lung cancer from marijuana cannot be ruled out. Unlike heavy tobacco smokers, heavy marijuana smokers exhibit no obstruction of the lung's small airway. That indicates that people will not develop emphysema from smoking marijuana.
MYTH: marijuana'S ACTIVE INGREDIENT, THC, GETS TRAPPED IN BODY FAT. Because THC is released from fat cells slowly, psychoactive effects may last for days or weeks following use. THC's long persistence in the body damages organs that are high in fat content, the brain in particular.
FACT: Many active drugs enter the body's fat cells. What is different (but not unique) about THC is that it exits fat cells slowly. As a result, traces of marijuana can be found in the body for days or weeks following ingestion. However, within a few hours of smoking marijuana, the amount of THC in the brain falls below the concentration required for detectable psychoactivity. The fat cells in which THC lingers are not harmed by the drug's presence, nor is the brain or other organs. The most important consequence of marijuana's slow excretion is that it can be detected in blood, urine, and tissue long after it is used, and long after its psychoactivity has ended.
