The psychoactive drug cannabis, also called marijuana or hashish, is produced from parts of the cannabis plant, primarily the cured flowers and gathered trichomes of the female plant. The major active chemical compound Δ9-tetrahydrocannabinol, commonly referred to as THC, has psychoactive and medicinal effects when consumed, usually by smoking or ingestion. Humans have consumed cannabis for thousands of years; in the 20th century there was a rise in the use of cannabis for recreational and religious purposes.
The possession, use, or sale of psychoactive cannabis products became illegal in many parts of the world in the early 20th century. Since then, while some countries have intensified the enforcement of cannabis prohibition, others have reduced the priority of enforcement to the point of de facto legality. The supplying of cannabis remains illegal almost everywhere in the world through the 1961 Single Convention on Narcotic Drugs, the 1971 Convention on Psychotropic Substances, and the 1988 United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, while simple possession of small quantities is tolerated in a few countries.
It is generally considered to be impossible to achieve a lethal overdose by smoking cannabis. According to the Merck Index, 12th edition, the LD50, the lethal dose for 50% of rats tested by inhalation, is 42 mg/kg of body weight. That is equivalent of a 165 lb (75 kg) man ingesting all of the THC in 21 one-gram cigarettes of high-potency (15% THC) cannabis buds at once, assuming no THC was lost through burning or exhalation. For oral consumption, the LD50 for rats is 1270 mg/kg and 730 mg/kg for males and females, respectively, equivalent to the THC in about a pound of 15% THC cannabis. Only with intravenous administration — an unheard-of method of use — may such a level be even theoretically possible.
Cannabis smoking
Cannabis smoking is the practice of using some form of combustion in order to release and vaporize the psychoactive drugs as smoke-like particles. The primary constituent of these drugs is the cannabis drug found in the cannabis plant. These escape into the air and are picked up by the respiratory system, then absorbed into the bloodstream where the drugs travel to the brain for their neurochemical effects to take place. It is a frequent occurrence in recreational drug use. Slow combustion breaks down certain cellulose products found in the cell walls of the cells of the cannabis plant. This allows access to some of the psychoactive elements inside while attempting to preserve as much of the drug as possible.
There are numerous methods for accomplishing this technique, but there are several which are the most popular. These vary in terms of how the plant parts are set up before combustion, which parts of the plant are combusted, and the treatment of the resulting smoke particles. Because smoking involves actual combustion, some of the drug gets degraded or destroyed, it is to be contrasted with vaporizing cannabis, where it is heated to a temperature slightly below the flash point of the plant parts in order to have the outer parts boil off, releasing the psychoactive drug parts into the air without it risking combustion. The difference in effect varies.
