A cytologic evaluation of sputum in marijuana smokers

There is growing evidence that smoking marijuana produces pulmonary effects similar to those of smoking tobacco. Cytologic analysis of sputum is readily available to practicing physicians and may be used in evaluating the pulmonary health of marijuana smokers. This study examined the use of sputum cytologic testing in young, athletic, marijuana-only smokers.

Sputum samples were collected from 25 marijuana-smoking members (surfers) who live in rural areas and do not smoke tobacco (mean age 27.5 years). The samples from the study group were compared with the sputum samples of 25 urban tobacco smokers and 25 nonsmokers of similar ages. Components of sputum were analyzed quantitatively and qualitatively. Subjects were educated and counseled as to the results.

Compared with nonsmokers, marijuana smokers showed significantly higher levels of all pathologic components (P < .05), but lower mean levels of neutrophils (5.4 vs 6.4, P = .005) and pigmented macrophages (4.9 vs 6.1, P < .001) than those of tobacco smokers. Two cases of dysplasia were noted among the tobacco smokers and one among the marijuana smokers. Test-result counseling of a limited data set (6 subjects) at 6 months resulted in a 50% self-reported cessation rate.

In this pilot study, results of cytologic evaluations in marijuana smokers closely resembled those observed in tobacco smokers. Further studies are needed to determine longitudinal and dose-related effects of marijuana smoking on cytologic changes. As a noninvasive testing method, sputum cytologic analysis may be a useful tool for evaluating the pulmonary health of marijuana smokers and may present an opportunity to counsel them on the benefits of cessation.