title: Marijuana and lung diseases.
abstract: OBJECTIVE
  Cannabis sativa (marijuana) is used throughout the world, and its use is increasing. In much of the world, marijuana is illicit. While inhalation of smoke generated by igniting dried components of the plant is the most common way marijuana is used, there is concern over potential adverse lung effects. The purpose of this review is to highlight recent studies that explore the impact upon the respiratory system of inhaling marijuana smoke.
  
  
  RESULTS
  Smoking marijuana is associated with chronic bronchitis symptoms and large airway inflammation. Occasional use of marijuana with low cumulative use is not a risk factor for the development of chronic obstructive pulmonary disease. The heavy use of marijuana alone may lead to airflow obstruction. The immuno-histopathologic and epidemiologic evidence in marijuana users suggests biological plausibility of marijuana smoking as a risk for the development of lung cancer; at present, it has been difficult to conclusively link marijuana smoking and cancer development.
  
  
  CONCLUSIONS
  There is unequivocal evidence that habitual or regular marijuana smoking is not harmless. A caution against regular heavy marijuana usage is prudent. The medicinal use of marijuana is likely not harmful to lungs in low cumulative doses, but the dose limit needs to be defined. Recreational use is not the same as medicinal use and should be discouraged.
authors.affiliation: aUniversity of Arkansas for Medical Sciences bCentral Arkansas, Veterans Healthcare System, Little Rock, Arkansas, USA.
authors.forename: Manish
authors.initials: M
authors.lastname: Joshi
authors.forename: Anita
authors.initials: A
authors.lastname: Joshi
authors.forename: Thaddeus
authors.initials: T
authors.lastname: Bartter
mesh_terms: D000403:Airway Resistance / Q000187:drug effects; D002188:Cannabis / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008171:Lung Diseases / Q000139:chemically induced* / Q000453:epidemiology / Q000503:physiopathology; D008175:Lung Neoplasms / Q000453:epidemiology / Q000209:etiology; D008385:Marijuana Smoking / Q000009:adverse effects* / Q000453:epidemiology / Q000503:physiopathology; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology / Q000209:etiology; D012129:Respiratory Function Tests; D012307:Risk Factors