Sustainability in the body
Most cannabinoids are lipophilic (fat soluble) compounds that are easily stored in fat, thus yielding a long elimination half-life relative to other recreational drugs. The THC molecule, and related compounds, are usually detectable in drug tests from 3 days up to 10 days according to Redwood Laboratories. Long-term users can produce positive tests for two to three months after ceasing cannabis use (see drug test). Toxicities
When cannabis is smoked, blood levels of THC peak rapidly after a few minutes and then decline, although the psychotropic effects persist for longer. Edible forms of cannabis often contain several hundred milligrams of THC, much more than the 32mg of a typical cannabis cigarette. The rise of edible cannabis products has been responsible for a large increase of poisoning of children and young people: in American states which have legalized cannabis, emergency room admissions of such cases have typically doubled. Symptoms in children can include lethargy, sedation and seizure.Cannabis is suspected of being a potential contributory factor or direct cause of sudden death, due to the strain it can place on the cardiovascular system, or because of cannabinoid hyperemesis syndrome. Related to cannabinoids
THC, the principal psychoactive constituent of the cannabis plant, has an extremely low toxicity and the amount that can enter the body through the consumption of cannabis plants poses no threat of death. In dogs, the minimum lethal dose of THC is over 3000 mg/kg.
A 2021 longitudinal study conducted among populations of HIV-positive and HIV-negative adults found that smoke-related carcinogenic toxicants and biomarkers detected in tobacco smokers were also detected in exclusive marijuana smokers, including carbon monoxide (CO), polycyclic aromatic hydrocarbons (PAHs), aldehydes (such as acrolein), acrylonitrile and acrylamide metabolites, but exposures are lower compared with tobacco or dual smokers. Increased levels of acrolein exposure by tobacco smoking but not exclusive marijuana smoking were detected both in HIV-positive and HIV-negative adults, and contribute to increased diagnoses of cardiovascular diseases and respiratory diseases among tobacco smokers.Cannabis smoke contains thousands of organic and inorganic chemical compounds. This tar is chemically similar to that found in tobacco smoke or cigars. Over fifty known carcinogens have been identified in cannabis smoke. These include nitrosamines, reactive aldehydes, and polycylic hydrocarbons, including benz[a]pyrene. Marijuana smoke was listed as a cancer agent in California in 2009. A study by the British Lung Foundation published in 2012 identifies cannabis smoke as a carcinogen and also finds awareness of the danger is low compared with the high awareness of the dangers of smoking tobacco particularly among younger users. Other observations include possible increased risk from each cigarette; lack of research on the effect of cannabis smoke alone; low rate of addiction compared to tobacco; and episodic nature of cannabis use compared to steady frequent smoking of tobacco. Professor David Nutt, a UK drug expert, points out that the study cited by the British Lung Foundation has been accused of both "false reasoning" and "incorrect methodology".