Currently, the highest-profile use for Cannabis is medicine ("medical marijuana"). Cannabis contains about 460 compounds, including over 80 cannabinoids. No anti-cancer properties have been documented with certainty, but placebo-controlled clinical trials indicate efficacy of marijuana in treating Tourette's, Lou Gehrig's disease, multiple sclerosis, irritable bowel syndrome, muscle spasticity, glaucoma, and anorexia. Another promising use is the treatment of chronic pain, against which marijuana works about as well as opioids (e.g. morphine and oxycodone) with fewer side effects. Marijuana's effectiveness against acute pain, however, is not significant.
|A botanical illustration of Cannabis sativa.|
The most notable hypothesized side-effect of extended regular marijuana use is the possibility of an increased risk of psychoses such as schizophrenia, especially for people who begin using the plant at a young age. While there seems to be a significant correlation between people who have used marijuana regularly in the past and schizophrenia, it is difficult for scientists to determine if marijuana causes the psychosis or if some underlying genetic pre-disposition towards psychosis is also a pre-disposition to marijuana use, hence the correlation. Much more research will need to be conducted to determine if there are in fact any long-term side effects of use.
Short-term side effects, which include lengthening of reaction time and impairment of attention, assessment of risks, concentration, and short-term memory, are much easier to prove. These effects can be present up to 24 hours after marijuana use, often with the user unaware of continued impairment several hours after use. The use of many methods of transportation and other machinery would therefore not be advisable for someone using marijuana for treatment.
Marijuana is not as addictive as other drugs like caffeine, tobacco, alcohol, cocaine, or heroin, but individuals can suffer from Cannabis Use Disorder, defined in the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders as a dependence on the plant experienced by about 9% of users.
|A medical marijuana shop in Denver, CO (photo by O'Dea at WikiCommons).|
Beyond medicinal use, Cannabis is employed extensively for material use under the name of "hemp," referring to the soft and durable fibers extracted from Cannabis sativa stems, which are most commonly used because they are the tallest (~18 ft.). Plants used for fiber production are usually bred to have low THC content so authorities can tell it's not being grown for drug use. Hemp cultivation has been dated back to over 10,000 years ago in China, where early uses included clothing, shoes, paper, and rope. Rope, sail canvas (the name "canvas" is derived from the name "Cannabis"), and oakum (ship caulking) have been the main uses of the plant since the 1400s for Europeans, who needed extensive sources for their ever-expanding navies and commercial ship fleets. Rope made from hemp is strong but needs to be tarred because it holds moisture and rots relatively easily without a protective coating. Hemp rope was eventually largely replaced by abaca (aka Manila hemp), which is a fiber derived from a species of banana (Musa textilis) and does not require tarring because it doesn't easily rot.
The United States made extensive use of hemp during World War II for uniforms, rope, and canvas because our Asian abaca sources were cut off by the Japanese. Here is a video produced by the United States in 1942 called "Hemp for Victory" detailing the need and uses for hemp, as well as how to grow, harvest, and process the crop:
As is shown in the video, because Cannabis grows so densely, it can be used by farmers as a rotation crop to help choke out weeds on cultivated land. This is especially useful to organic farmers, who need to find ways to kill weeds without synthetic herbicides. Dense plantings of hemp can also be used in phytoremediation - the use of plants to clean undesirable compounds from the soil including heavy metals such as lead, nickel, and cadmium. While this capability is good for phytoremediation, it is a property that significantly hinders its use for other applications.
Even though Japan has some of the most severe penalties for marijuana possession (5 years imprisonment), they make exceptions for growers to produce enough hemp for robes for Buddhist monks and hemp belts for the highest ranking Sumo wrestlers known as yokozuna, who traditionally wear them during ritual cleansings of sumo rings. Hemp is stronger than cotton, but although fabric for clothing can be made from hemp alone, it is most commonly blended with cotton at about a 1:1 ratio for softness.
|A yokozuna wearing a heavy (25-35 lbs) hemp belt during a ritual cleansing of a sumo ring (photo from Kannaway Magazine).|
Hemp seeds are quite nutritious, and while they are currently most commonly used in animal and bird feed, they have great potential for human nutrition. The seeds contain plenty of omega-3's and omega-6's and also have a "complete" protein profile, meaning that they contain all the nutritionally significant amino acids, including the nine essential amino acids that human bodies cannot produce. The seeds can be eaten raw or used in a variety of ways, including baking, hemp milk, cereals, tofu, nut butter, and ice cream. Hemp seeds can also be processed into biodiesel.
|A small selection of hemp food products (photo from freedweed.wordpress.com).|
Hemp is often an ingredient in biodegradable plastics, and has been an ingredient in composite automobile panels by major car manufacturers since 2002. The harder inner parts of older Cannabis stems can be used as a wood replacement for certain house construction applications.
Although hemp was used to make early paper in China, it is not too practical a commercial option because of the processing involved, resulting in costs that add up to about six times those involved in making paper from wood pulp. A couple major reasons for this are that hemp can be harvested only once per year and only about 25% of any given hemp stalk can be used for the paper, as opposed to nearly 100% from harvested trees.
As you can see, Cannabis is quite a useful plant for more than just "getting high," though it does have its limitations, some of which will require more study to determine the plant's commercial viability. You'll likely see it in more and more products as time goes on if regulations on the plant continue to ease.