Smoked marijuana as a cause of lung injury

Division of Pulmonaiy & Critical Care Medicine, Department of Medicine, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095-1690, USA.
Monaldi archives for chest disease = Archivio Monaldi per le malattie del torace / Fondazione clinica del lavoro, IRCCS [and] Istituto di clinica tisiologica e malattie apparato respiratorio, Università di Napoli, Secondo ateneo 07/2005; 63(2):93-100.
Source: PubMed


In many societies, marijuana is the second most commonly smoked substance after tobacco. While delta9-tetrahydrocannabinol (THC) is unique to marijuana and nicotine to tobacco, the smoke of marijuana, like that of tobacco, consists of a toxic mixture of gases and particulates, many of which are known to be harmful to the lung. Although far fewer marijuana than tobacco cigarettes are generally smoked on a daily basis, the pulmonary consequences of marijuana smoking may be magnified by the greater deposition of smoke particulates in the lung due to the differing manner in which marijuana is smoked. Whereas THC causes modest short-term bronchodilation, regular marijuana smoking produces a number of long-term pulmonary consequences, including chronic cough and sputum, histopathologic evidence of widespread airway inflammation and injury and immunohistochemical evidence of dysregulated growth of respiratory epithelial cells, that may be precursors to lung cancer. The THC in marijuana could contribute to some of these injurious changes through its ability to augment oxidative stress, cause mitochondrial dysfunction, and inhibit apoptosis. On the other hand, physiologic, clinical or epidemiologic evidence that marijuana smoking may lead to chronic obstructive pulmonary disease or respiratory cancer is limited and inconsistent. Habitual use of marijuana is also associated with abnormalities in the structure and function of alveolar macrophages, including impairment in microbial phagocytosis and killing that is associated with defective production of immunostimulatory cytokines and nitric oxide, thereby potentially predisposing to pulmonary infection. In view of the growing interest in medicinal marijuana, further epidemiologic studies are needed to clarify the true risks of regular marijuana smoking on respiratory health.

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    • "Les liens entre le tabac et le cancer bronchique sont clairement établis depuis les travaux de Doll et Peto [2] [3], en revanche ceux qui existent avec le cannabis sont moins bien connus 4—7. Des effets carcinogènes de la fumée de cannabis indépendants de ceux du tabac sont identifiés [8]. Le cannabis est la substance psychoactive (SPA) illicite la plus consommée dans le monde [9]. "
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    ABSTRACT: Cannabis is the most commonly smoked illicit substance in the world. It can be smoked alone in plant form (marijuana) but it is mainly smoked mixed with tobacco. The combined smoking of cannabis and tobacco is a common-place phenomenon in our society. However, its use is responsible for severe pulmonary consequences. The specific impact of smoking cannabis is difficult to assess precisely and to distinguish from the effect of tobacco. Marijuana smoke contains polycyclic aromatic hydrocarbons and carcinogens at higher concentration than tobacco smoke. Cellular, tissue, animal and human studies, and also epidemiological studies, show that marijuana smoke is a risk factor for lung cancer. Cannabis exposure doubles the risk of developing lung cancer. This should encourage clinicians to identify cannabis use and to offer patients support in quitting.
    Revue des Maladies Respiratoires 06/2014; DOI:10.1016/j.rmr.2013.12.002 · 0.62 Impact Factor
    • "[18] A longitudinal study of 1037 New Zealand youths followed until the age of 26 [20] found impaired respiratory function in dependent cannabis users but this finding was not replicated in a longer-term follow-up of US users. [19] Chronic cannabis smoking has not been found to increase the risk of emphysema in 8–20-year follow-ups in cannabis smokers in the USA [21] [22] and New Zealand. [23] Respiratory cancers "
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    ABSTRACT: This paper summarizes the most probable of the adverse health effects of regular cannabis use sustained over years, as indicated by epidemiological studies that have established an association between cannabis use and adverse outcomes; ruled out reverse causation; and controlled for plausible alternative explanations. We have also focused on adverse outcomes for which there is good evidence of biological plausibility. The focus is on those adverse health effects of greatest potential public health significance - those that are most likely to occur and to affect a substantial proportion of regular cannabis users. These most probable adverse effects of regular use include a dependence syndrome, impaired respiratory function, cardiovascular disease, adverse effects on adolescent psychosocial development and mental health, and residual cognitive impairment. Copyright © 2013 John Wiley & Sons, Ltd.
    Drug Testing and Analysis 01/2014; 6(1-2). DOI:10.1002/dta.1506 · 2.51 Impact Factor
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    • "Heavier cannabis use in adolescence correlates with lower life satisfaction and worse financial and social outcomes in young adulthood (Fergusson & Boden, 2008). Medically, inhaled cannabis smoke is more harmful to the lungs than tobacco smoke because it contains 50-70 percent more carcinogenic hydrocarbons, is inhaled more deeply, and is held in longer (Tashkin, 2005). Cannabis use is associated with psychiatric conditions such as psychosis, mood disorders, anxiety, disruptive behavior, and problems with other substances (Elkins, McGue, & Iacono, 2007; Etain et al., 2013; Lai & Sitharthan, 2012; Rey, Sawyer, Raphael, Patton, & Lynskey, 2002). "
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    ABSTRACT: Background: Cannabis (marijuana) is used by half of all adolescents. Commonly held beliefs that this psy- choactive substance is harmful to adolescents coexist with views that cannabis is a harmless natural substance that has beneficial effects. These culturally-ingrained attitudes can have more powerful effects on policy and behavior than ex- perimental evidence. It is important to address the potential imbalance between the influence of cultural attitudes and ob- jective data especially during this period when official sanction of cannabis is in transition across the United States. Methods: This review presents the scientific literature on neuropsychological functioning in adolescents who use canna- bis. These experimental data are organized along the constructs of the cognitive systems domain delineated by the Re- search Domain Criteria (RDoC) of NIMH. Review of data on social and emotional functioning in cannabis-using adoles- cents is not a focus of this article. Results: Adolescents who use cannabis regularly and heavily have impairments in a number of areas of cognition that in- clude attention, declarative memory, and cognitive control. Some impairments may be dose dependent, worse the younger the age of initiation, and persistent in abstinence. The ways in which gaps in this literature hinder the interpretation and broad application of the findings are described. Conclusions: There are sufficient research data to raise concerns that regular cannabis use is detrimental to mental func- tioning of adolescents. The literature suggests that because the adolescent brain is developing, it is more sensitive to any adverse effects of cannabis. Still, further research is needed to better understand cannabis and the brain, specifically ac- counting for neurocognitive functioning before initiation of cannabis, different degrees of use, and the long-term conse- quences of use and abstinence.
    Adolescent psychiatry 06/2013; 3(2):153-147. DOI:10.2174/2210676611303020004
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