Chest
Volume 112, Issue 2, August 1997, Pages 319-326
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Tracheobronchial Histopathology in Habitual Smokers of Cocaine, Marijuana, and/or Tobacco*

https://doi.org/10.1378/chest.112.2.319Get rights and content

Background

Marijuana and alkaloidal cocaine (“crack”) are the two most commonly smoked substances in the United States after tobacco. While regular tobacco smoking has been found to be associated with extensive microscopic alterations in bronchial mucosa, little information is available concerning the effect of crack cocaine and marijuana on tracheobronchial histopathology.

Study objective

To determine the relative impact of smoked substances (cocaine, marijuana, and tobacco) alone and in combination on the histopathology of the tracheobronchial mucosa and to assess whether the effects of habitual smoking of two or more substances (cocaine, marijuana, and/or tobacco) are additive.

Design

Observational cohort study.

Subjects

Fifty-three nonsmoking control subjects (NS), 14 current, habitual smokers of crack cocaine only (CS), 40 current, regular smokers of marijuana only (MS), 31 regular smokers of tobacco only (TS), 16 current smokers of both cocaine and marijuana (CMS), 12 current smokers of both cocaine and tobacco (CTS), 44 current smokers of both marijuana and tobacco (MTS), and 31 current smokers of cocaine, marijuana, and tobacco (CMTS).

Methods

After preliminary screening evaluation, including a detailed respiratory and general health questionnaire and routine pulmonary function studies, subjects underwent fiberoptic bronchoscopy with endobronchial biopsies of the mucosa of the primary carina and randomly selected secondary or tertiary carinae. Biopsy specimens were processed for light microscopy, stained with hematoxylin-eosin or periodic acid-Schiff, and examined to assess epithelial, basement membrane, and submucosal alterations by one or two pathologists who were masked to the smoking status of the subject.

Results

Smokers of cocaine, marijuana, or tobacco alone all exhibited more frequent abnormalities than NS in 10 (CS) or all 11 (MS and TS) of the histopathologic features assessed. For most features, MS and TS showed significantly more frequent alterations than NS (p ≤ 0.02), while CS showed significantly more frequent abnormalities than NS in only three features (p<0.05) and nearly significant differences from NS in two additional features (p ≤ 0.09). Alterations were noted most frequently in CTS (six features) and MTS (three features), while abnormalities were relatively infrequent in CMS. For 10 features, MTS had more frequent alterations than MS and TS. With a single exception, CMTS did not show more frequent alterations than CTS or MTS.

Conclusions

Marijuana and tobacco smoking each produces significant bronchial mucosal histopathology and the effects of marijuana and tobacco appear additive. Cocaine appears to lead to fewer significant bronchial mucosal alterations than marijuana or tobacco when smoked alone and does not add to the changes associated with marijuana. When smoked together with tobacco, however, cocaine appears to augment the bronchial injury caused by tobacco smoking.

Section snippets

Subjects

Male and female subjects 21 to 50 years of age were recruited for bronchoscopic study from a cohort of participants in an ongoing longitudinal study of the pulmonary effects of heavy, habitual smoking of marijuana and/or cocaine, with or without tobacco.8, 9 Participants in this study also included a comparison group of age-matched smokers of tobacco alone, as well as nonsmokers of similar age, residing in metropolitan Los Angeles. To be included in the bronchoscopic study, marijuana smokers

Results

Technically satisfactory biopsy specimens were obtained in 241 healthy volunteers (82.6% male; mean age, 35.4±8.3 [SD] years). Table 2 lists the number, gender, and mean age of the subjects in each smoking category and their frequency and duration of smoking marijuana, cocaine, and/or tobacco. Most subjects in all smoking categories were male. Smokers in all categories were slightly older than the nonsmokers, but smokers of cocaine, marijuana, and/or tobacco were of comparable age. Smokers of

Discussion

We performed and evaluated bronchial mucosal biopsy specimens in smokers of one or more of three commonly smoked substances (cocaine, marijuana, and tobacco), as well as in nonsmoking control subjects. Of the 241 biopsy specimens analyzed, 158 were new tissue samples (including samples from 73 smokers of cocaine alone or with marijuana and/or tobacco) not included in our previously published reports.5, 6, 7 Consistent with trends that were apparent from these earlier studies,5, 6, 7 results now

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Supported by NIDA/NIH grants RO1 DA08254 and RO1 03018.

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