MORE ON POT

Allowing 28 healthy young men to smoke as much marijuana as they wish for 72 days produced significant pulmonary impairment in research described at the Interational Conference on Lung Diseases in Montreal. Others have measured expansion in the airways of patients with stable bronchial asthma immediately after smoking marijuana and the drug has been suggested as a useful bronchodiator, but other studies suggest bronchitis may follow heavy or chronic use. The investigation described here indicated long-term use of marijuana causes mild but significant airway narrowing. The 28 volunteers ranging in age from 21 to 33 years were confined for 94 days. None had obvious lung disease, and all customarily smoked marijuana at least four days a week. Twenty-three of the volunteers either had never smoked tobacco or had not smoked cigarettes for six months. Four smoked less than half a pack a day. "Detoxification" was scheduled during the first 11 days of confinement, with no marijuana smoking allowed. pulmonary function tests were performed during this period, and repeated on the fourth day after smoking was permitted and on either day 48 or day 60. The volunteers smoked as many joints as desired during the entire intoxification period. Each joint contained 900 mg of marijuana, and an average total of 377 joints, or 5.2 joints per day were smoked during the course of the study. Lung function tests suggested 47 to 59 days of smoking marijuana produced significant increases in resistance in both large and small airways, and a small, but significant impairment in single-breath diffusing capacity for carbon monoxide.