ACUTE AND CHRONIC EFFECTS OF MARIJUANA SMOKING ON PULMONARY ALVEOLAR PERMEABILITY

Pulmonary clearance of technetium (Tc-99m)-labeled diethylene triamine pentaacetate (DTPA), a sensitive test of alveolar epithlelial permeab ility, was measured twice in 34 healthy subjects, including 10 control nonsmokers (NS), 10 habitual smokers of marijuana alone (MS) (greater than or equal to 10 joints/wk), 9 regular smokers of tobacco alone (T S) (greater than or equal to 15 cigarettes/day) and 4 habitual smokers of both marijuana and tobacco (MTS). In smokers, the first study was performed after greater than or equal to 12 hrs of abstinence from smo king to assess chronic effects of marijuana and/or tobacco smoking on alveolar permeability; the second study was performed within 15 min of smoking to assess possible acute effects. TS exhibited abnormally rap id Tc-99m-DTPA clearance after greater than or equal to 12 hours of ab stinence, indicating an increase in pulmonary epithelial permeability, consistent with chronic tobacco-induced lung injury. MS showed a more modest and less consistent chronic effect than TS on Tc-99m-DTPA clea rance, suggesting a more variable and smaller degree of marijuana-indu ced lung injury. No acute effect of tobacco or marijuana smoking on Tc -99m-DTPA clearance was apparent. Concomitant habitual smoking of mari juana and tobacco had no additive effect on alveolar permeability.