Science Fair Project Encyclopedia
- This article is about cannabis used as a drug. For other uses, see cannabis.
Cannabis has been used as a drug for thousands of years but has become much more popular during the twentieth century. The use of the cannabis as a recreational drug became illegal in most parts world during the early twentieth century, and remains that way today. For the physiology and science of the plant see Cannabis sativa.
Acute effects of human consumption
Acute effects of cannabis consumption vary according to the dose, the variety of the plant, the method of use, the individual, and the environment, but for the general population usually include some of the following:
- General change in consciousness
- Mild euphoria, feelings of general well-being
- Relaxation or stress reduction
- Increased appreciation of humor, music and other art
- Holistic attention, introspection
- Enhanced recollection of episodic memory
- Physical pleasure
- Increased sensuality
- Loss of inhibition
- Increased awareness of sensation
- Creative or philosophical thinking
- Initial wakefulness followed by drowsiness and lassitude
- Increased consciousness of body and mind connection
- Disruption of linear memory
- Difficulty with working memory
- Slowness, caution
- Paranoia, agitation, and anxiety
- Auditory and visual hallucinations, in some cases
- Precipitation or exacerbation of latent or existing mental disorders
- Subjective potentiation of other drugs
- Increased awareness of patterns and color
- Pain relief (especially headaches and cramps) but intensification of pain is also possible.
- Increased appetite
- Reduced nausea
- Dilation of alveoli (air sacs) in lungs
- Dilation of blood vessels (vasodilation), resulting in:
- Increased blood flow and heart rate
- Reddening of the conjunctivae (red eye)
- Dry mouth (xerostomia)
- Aphrodisiacal qualities
- Dizziness, confusion
- Lower intra-ocular pressure (within the eyeball)
- Lower blood pressure while standing. Higher blood pressure while sitting
- Increased metabolism of glucose, reducing blood sugar levels
Of the approximately 400 different chemicals found in Cannabis, the main active ingredient is THC (delta-9-tetrahydrocannabinol).
THC has an effect on the modulation of the immune system which may have an effect on malignant cells, but there is insufficient scientific study to determine whether this might promote or limit cancer. Cannabinoid receptors are also present in the human reproductive system, but there is insufficient scientific study to conclusively determine the effects of cannabis on reproduction. Mild allergies to cannabis may be possible in some members of the population.
No fatal overdose due to cannabis use has ever been recorded in humans. According to the Merck Index, 12th edition, the LD50, the lethal dose for 50% of tested rats, was 42 milligrams per kilogram of body weight with forced inhalation. As for oral consumption, the LD50 for rats was 1270 mg/kg and 730 mg/kg for males and females, respectively. It would be impossible for THC in blood plasma to reach such a level in human cannabis smokers. Only with intravenous administration, a method rarely or never used by humans, may such a level be possible. Also, some evidence suggests that toxic levels may be higher for humans than for rats.
Long-term effects of human consumption
There is little conclusive scientific evidence about the long-term effects of human cannabis consumption. Many old studies which purported to demonstrate such effects were deeply flawed, with strong bias and poor methodology. The most significant confounding factor in determining long-term effects is the use of other drugs by test subjects in studies of cannabis use. When subjects who use only cannabis are combined in the same sample with subjects who use other drugs, an experiment could not conclude that its findings are indicative of an effect of the use of cannabis rather than an effect of the use of other drugs, or an effect of a complex combination of cannabis with other drugs.
Tolerance, withdrawal and dreams
Although use may become habitual, the extent of physical dependence to marijuana is largely unknown. (DEA, 2004) Yet, many animal and human studies conducted since the 1970s have revealed a marijuana withdrawal syndrome after abstinence from heavy, chronic use. Withdrawal symptoms, although far less severe than that of alcohol, heroin, or cocaine, do exist and are usually characterized by several days of anxiousness, sleeplessness, irritability, and diminished appetite after cessation of use. Also more vivid, memorable dreams (REM rebound) are common in heavy users who temporarily abstain. However, because cannabis is a peculiar psychedelic that is unlike typical depressant or stimulant drugs, these persistent effects are unlike those normally associated with physical dependence. In particular, because THC has a very long half-life, working its way out of the body slowly over many days, it thereby obviates severe withdrawal effects seen in other substances.
Long-term effects on the mind and brain
In some people, cannabis use appears to cause significant medium-term decreases in cognitive performance, but performance on general intelligence and cognitive tests returns to "normal" in those people affected in this way within weeks of abstinence depending on the level of use. However, subtle impairment of complex cognitive function may persist even after long periods of abstinence in some of the users who suffered from decreased cognitive performance in the first place. Some studies have claimed that long-term heavy users become prone to apathy.
There is a correlation in some people between cannabis use and psychosis, schizophrenia, and clinical depression, but there is no evidence that cannabis use causes these illnesses. Rather, cannabis may trigger latent conditions or be part of a complex coordination of causes, referred to as the diathesis-stress model in psychology. On the other hand, many people with pronounced psychological disorders, especially schizophrenia and depression, often self-medicate their illness with cannabis in place of potent main-stream drugs like antipsychotics, due to marijuana's relatively low side effects and calming physiological effects that alleviate symptoms.
Some claim that extended use of cannabis may help a human reach a higher level of consciousness, expand the mind and help them become more aware. It can be used to increase performance in certain areas. In Jamaican culture it has long been seen in this way.
Long-term physical effects of smoking
In some ways, the effects of smoking cannabis are similar to the effects of smoking tobacco. Any time a substance is combusted for the purpose of producing smoke for inhalation, the respiratory system is adversely affected. These effects are particularly apparent with repeated and prolonged use. Studies have pointed out that cannabis produces more tar than tobacco, and cannabis smokers inhale the smoke deeper and longer into their lungs, but the average cannabis user smokes far less frequently and usually shares with others. In both cases, additional health problems may also result from the many toxic and carcinogenic chemicals that are also inhaled. However, the concentration of additives, like nicotine, arsenic, and radioactive Radium 226, is substantially greater in tobacco cigarettes. Much of the farmland used to grow tobacco in the United States is contaminated with radioactive material as a result of using fertilizers rich in phosphates. In 1990, U.S. Surgeon General C. Everett Koop declared that "radioactivity, not tar, accounts for at least 90% of all smoking related lung cancer." Studies by Winters et al., in the New England Journal of Medicine (1982), found that skeletons of cigarette smokers contained deposits of Lead 210 and Polonium 210, two daughter elements of radioactive Radium found in the soil of tobacco plants. While some studies have demonstrated a correlation between cannabis use and lung cancer, more objective scientific attention is needed to understand all of the long-term physiological effects of cannabis use.
Medically, cannabis is most often used as an appetite stimulant and pain reliever for certain terminal illnesses such as cancer and AIDS. It is also used to relieve glaucoma and certain neurological illnesses such as epilepsy and bipolar disorder. The medical use of cannabis is politically controversial, but it is sometimes recommended informally by physicians. A synthetic version of the active ingredient in cannabis, THC, is readily available in the form of a pill as the prescription drug Marinol. THC has also been found to reduce arterial blockages.
See section History for information on historic and other medical use.
Cannabis has a long history of spiritual use, especially in India, where it has been used by wandering spiritual aspirants for centuries. The most famous religious group to use cannabis in a spiritual context are the Rastafarians, though they are by no means the only group.
It is not known when or why the Rastafarians made marijuana into something sacred, though it is clear that by the late nineteen-forties Rastafari was associated with cannabis smoking at the Pinnacle community of Leonard Howell. Rastafarians believe that marijuana is the tree of life mentioned in the Revelations chapter of the Bible. Bob Marley, amongst many others, said, "the herb (marijuana) is the healing of the nations". The use of marijuana, and particularly of large pipes called chalices, is an integral part of what Rastafarians call Reasoning sessions. They see marijuana as having the capacity to allow the user to penetrate the truth of how things are much more clearly, as if the wool had been pulled from the eyes of the former non-user. Thus the Rastafarians come together to smoke marijuana in order to discuss the truth with each other, reasoning it all out little by little through many sessions. In this way marijuana brings the user closer to God, according to Rastafarian beliefs. The lighting of the chalice is always accompanied by many thanks and praises to the Rastafarian God, spoken by a different person to the one actually smoking the pipe into life.
Many individuals also consider their use of cannabis to be spiritual regardless of organized religion.
Preparations for human consumption
Cannabis is prepared for human consumption to several forms:
- Marijuana or buds, the resin gland-rich flowering tops of female plants.
- Kif or kief, a powder containing the resin glands (glandular trichomes, often incorrectly called "crystals" or "pollen"). It is produced by sifting marijuana and leaves.
- Hashish, a concentrated resin made from pressing kif into blocks.
- Charas, produced by hand-rubbing the resin from the resin gland-rich parts of the plant. Often thin dark rectangular pieces.
- Bhang, prepared by the wet grinding of the leaves of the plant and used as a drink.
- Hash oil, resulting from extraction or distillation of THC-rich parts of the plant.
- Minimally potent leaves and detritus, called shake, bush or leaf.
The most common method of cannabis consumption is by smoking a hit through one of several classes of devices:
- By rolling it up, usually manually, into a cigarette, often called a joint, with thin rolling papers, or into a cigar, often called a blunt, with papers obtained by removing the tobacco from a standard cigar. In such preparation, tobacco or other smokable material are sometimes combined into a single roll.
- By using a pipe, often called a bowl, usually made of blown glass, wood, or sometimes metal. Blown-glass pipes are usually intricately and colorfully designed, with colors becoming more vivid after repeated use. Such pipes usually have a rush or carb hole which is covered by a finger for suction when beginning smoking, which is released to finish inhalation without advancing the burning any further. Tobacco pipes, pipes home-made by the user, and others, are also sometimes used. Some users prefer a vertically held ceramic or glass pipe, known as a chillum, coming from India.
- In a water-pipe, or bong, by which the smoke is filtered through water so that it is cooler and less harmful to the lungs. When the smoke passes through the water, some of the undesirable particals in the smoke, such as tar, are filtered out. In water-pipes, the cannabis is placed into a bowl, which may be removable, and smoke is sucked through a body of water into a large chamber which is cleared by inhaling further after the rush hole is uncovered or the pipe-like part is removed. A hookah is a similar, water-filtering device with a long, flexible tube which the user may hold, through which the smoke passes before entering the mouth. Hookahs often have several tubes so that multiple users may smoke at the same time.
- More rarely, a gravity bong (NZ: bucket bong), usually home-made, consists of a large water-filled bucket and a funnel, such as a milk jug or soft-drink bottle, with an open-ended or cut-out bottom and a bowl that can be sealed into the top when capped. The uncapped funnel is lowered into the water-filled bucket and then capped with the bowl of cannabis. The cannabis is then lit while slowly raising the funnel from the bucket, so that there is a negative air pressure in the funnel by which gas and smoke is pulled through the bowl. The raising of the now-smoke-filled funnel is stopped before the funnel is fully removed from the water, the cap is removed, and the user inhales from the top while carefully pushing the funnel back into the water. The volume of smoke with this method is less easily controlled and can be hazardous.
- A further method, commonly referred to as spotting or hot knives, is when two knives are heated (usually on a stove-top element) until red-hot. A small amount of resin, or marijuana (oil or bud), known as a spot is then pressed between the knives and the resulting smoke inhaled through a funnel, often made from a bottomless soft-drink bottle. This method is often used when no other materials for smoking are at hand, and is also thought to be more efficient, as there is no idle burning between inhalations.
Cannabis may be orally consumed by blending it with alcohol or fats. With this method, some claim that more cannabis must be used. The effects of the drug take longer to begin, but last longer and may be more physical rather than mental. It takes some experience for one to regulate the dose. Common preparations involve blending with butter that is used in preparing brownies, fudge or cookies. Infusion in drinks containing milk and flavoring herbs is also possible, and more common in India.
To prepare cannabis for oral consumption, it must be done with fats or alcohol. Contrary to popular belief, Cannabis Tea does not contain significant amounts of THC, because THC, along with the other cannabinoids, is highly insoluble in water, but readily dissolves into the fats and alcohol. The tea is, however, reputed to be a tasty and relaxing drink.
The seeds of the plant, high in protein and fatty acids, can also be roasted and eaten. They contain little THC.
See Cooking with cannabis external links below.
Usually with a vaporizer, cannabis can be heated to a temperature at which the active ingredients are released into gaseous form with little or no burning of the plant material. With this method, the user does not inhale as many toxic chemicals that are byproducts of combustion and so may be more healthy. Some people claim to experience subtly different effects when using cannabis in this way.
The use of cannabis, for food, fibers, and medicine, is thought to go back at least five millennia. Neolithic archaeological sites in China include cannabis seeds and plants. The first known mention of cannabis is in a Chinese medical text of 2737 BC. It was used as medicine throughout Asia and the Middle East to treat a variety of conditions. In India particularly, some sects of Hinduism associated cannabis with Shiva.
Cannabis was well known to the Scythians, as well as by the Thracians/Dacians, whose shamans (the kapnobatai - "those who walk on smoke/clouds") used to burn cannabis flowers in order to induce trances. The cult of Dionysus, which is believed to have been originated in Thrace, has also been linked to the effects of cannabis smoke.
American pioneers depended on hemp for clothes, canvas, rope, oil, food, and many other things. The plant was so important that Thomas Jefferson, as governor of Virginia, required every farmer in the state to plant hemp for the good of the economy and citizens' survival. In 1791, the cotton gin was invented and cotton began to replace hemp for clothing in the U.S.
Under the name cannabis 19th century medical practitioners helped to introduce the herb's drug potential (usually as a tincture) to modern English-speaking consciousness. It was famously used to treat Queen Victoria's menstrual pains, and was available from shops in the US. By the end of the 19th century its medicinal use began to fall as other drugs such as aspirin took over.
The name marijuana is Mexican or Latin American in origin and associated almost exclusively with the herb’s drug potential. That marijuana is now well known in English as a name for drug material is due largely to the efforts of US drug prohibitionists during the 1920s and 30s.
Until 1937, consumption and sale of marijuana was legal in most American states. In some areas it could be openly purchased in bulk from grocers or in cigarette form at newsstands, though an increasing number of states had begun to outlaw it. In that year, federal law made possession or transfer of marijuana (without the purchase of a by-then incriminating tax stamp) illegal throughout the United States. This was contrary to the advice of the American Medical Association at the time. Legal opinions of time held that the federal government could not outlaw it entirely. The tax was $100 per pound of hemp, even for clothes or rope. The expense, extremely high for that time, was such that people stopped buying and making it.
The decision of the U.S. Congress was based in part on testimony derived from articles in the newspapers owned by William Randolph Hearst, who was heavily interested in DuPont Inc. Some analysts theorize DuPont wanted to boost declining post-war textile sales, and wished to eliminate hemp fiber as competition. Many argue that this seems unlikely given DuPont's lack of concern with the legal status of cotton, wool, and linen; although it should be noted that hemp's textile potential had not yet been largely exploited, while textile factories already had made large investments in equipment to handle cotton, wool, and linen. Others argue that Dupont wanted to eliminate cannabis because its high natural cellulose content made it a viable alternative to the company's developing innovation: modern plastic. Still, others could argue that hemp could never truly compete with the high strength and elasticity of synthetics, such as nylon.
Even more inflammatory and biased were the accusations by that period's US 'drug czar' Henry (Harry) Anslinger. Anslinger charged that the drug could provoke criminal behavior in previously solid citizens. Anslinger also popularized the word marihuana for the plant, using a Mexican derived word (believed to be derived from a Brazilian Portuguese term for inebriation) in order to associate the plant with increasing numbers of Mexican immigrants, creating a negative stereotype which persists to this day.
The 1937 federal marijuana tax act was struck down by the Supreme Court in 1969. In a case brought by Timothy Leary, the Court held that the law's requirement that a possessor of marijuana present the substance before receiving the stamp, thereby placing the possessor in violation of the law against unlicensed possession, violated the Fifth Amendment privilege against self-incrimination. In 1970, the Controlled Substances Act made possession of marijuana illegal again, without the constitutional issues that scuttled the 1937 act. Several petitions for cannabis rescheduling in the United States have been filed, since the Act permits legalization of marijuana through the executive branch.
Although cannabis has been used recreationally throughout its history, it first became well known in the United States during the jazz music scene of the late 1920s and 30s. Louis Armstrong became one of its most prominent and life-long devotees. Cannabis use was also a prominent part of 1960s counterculture.
Since the twentieth century, most legal jurisdictions of the world have laws against the cultivation, use, possession, or transfer of cannabis (and these laws impact adversely of course on the herb's cultivation for non-drug purposes) but there are many regions where certain circumstances of cannabis handling are legal or licensed and others where laws against its use, possession, or sale are not enforced. Many jurisdictions have also decriminalized possession of small quantities of cannabis, so that it is punished by confiscation and/or a fine, rather than imprisonment. By effectively removing the user from the criminal justice system, decriminalization focuses more on those who traffic and sell the drug on the black market. Increasingly, many jurisdictions also permit cannabis use for medicinal purposes.
- 420 (drug culture)
- coffee shop
- Drug policy of the Netherlands
- Dugout (smoking)
- Emerald Triangle
- Hash oil
- Head shop
- Cannabis: Health issues
- Jack Herer
- Cannabis: Legal issues
- Fitz Hugh Ludlow ("The Hasheesh Eater")
- Magic Brownie
- Medical marijuana
- Marijuana Parties
- Soap bar
- Shotgun (cannabis)
- Street names
- War on Drugs
- Wiktionary Appendix of Cannabis Slang
- Erowid Drug Information
- Good Drugs Guide
- Marijuana and Medicine: Assessing the Science Base
- Marijuana: The facts from the Lindesmith Center
- UN Drug Control and Prevention factsheet
- A Brief History of the War on Drugs
- A complete Timeline & History of Americas War on Drugs
- How Marijuana Became Illegal Smokedot.org's take of the history of criminalisation.
- The Emperor Wears No Clothes Jack Herer's book, partially online.
Growing the plant
Cooking with cannabis
- Cannabis News, A nonprofit news tracking and discussion site.
- BBC Panoroma programme on medical trials
- Canadian Foundation for Drug Policy: Senate hearing on cannabis.
- War on Drugs FAQ
- WHO report on Cannabis health effects
- Dr. Dave's Hemp Archives
- Hemp Industries Association
- Vote Hemp
- Global Hemp Resources
- North American Industrial Hemp council
- alt.hemp FAQ
- A history of the Marihuana Tax Act
- Kentucky Hemp Outfitters' Library
- Jack Herer and The Emperor Wears No Clothes
- Hemp For Victory, a 1942 US propaganda movie
- Vaporinfo with information about and reviews of vaporizers
- Ya-Hooka Site that indexes marijuana-related websites
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