The human toxicity of marijuana.

The pathophysiological effects of marijuana smoke and its constituent cannabinoids were reported first from in-vitro and in-vivo experimental studies. Marijuana smoke is mutagenic in the Ames test and in tissue culture and cannabinoids inhibit biosynthesis of macromolecules. In animals, marijuana or delta 9-tetrahydrocannabinol (THC), the intoxicating material it contains, produces symptoms of neurobehavioural toxicity, disrupts all phases of gonadal or reproductive function, and is fetotoxic. Smoking marijuana can lead to symptoms of airway obstruction as well as squamous metaplasia. Clinical manifestations of pathophysiology due to marijuana smoking are now being reported. These include: long-term impairment of memory in adolescents; prolonged impairment of psychomotor performance; a sixfold increase in the incidence of schizophrenia; cancer of mouth, jaw, tongue and lung in 19-30 year olds; fetotoxicity; and non-lymphoblastic leukemia in children of marijuana-smoking mothers.