The effects of secondhand smoke exposure on HRCT findings among asbestos-exposed workers

There is evidence suggesting that secondhand smoke (SHS) exposure is causally linked to adverse respiratory effects. We examined the relations between the exposure to SHS and radiological signs in chest high-resolution computed tomography (HRCT).

Asbestos-exposed workers (n=633) were imaged with HRCT, primarily to investigate potential occupational lung disease. After excluding current smokers, the study population included 361 ex- and 141 never-smokers. They answered a questionnaire on occupational exposures, smoking habits and SHS exposure. HRCT images were assessed for emphysema, ground-glass, irregular/linear and rounded opacities, honeycombing and several other signs. Regression analyses were adjusted for asbestos exposure, ex-smoking, age, body mass index and potential reader effect.

Due to missing data the multivariate analyses were restricted to 310 participants aged 47.5-87.0 years. Their lifetime SHS exposure ranged between 0 and 193.5 pack-years (mean 23.5), and exposure in the past 12 months 0-30 packs (0.43). Total (B=0.005, 95% confidence intervals (95% CI) 0.002-0.008, p=0.000) and workplace (B=0.006, 95% CI 0.003-0.009, p=0.001) cumulative SHS exposures were significantly related to ground-glass opacities. Total SHS exposure in the last 12 months (B=0.027, 95% CI 0.000-0.054, p=0.048) and workplace exposure (B=0.027, 95% CI 0.000-0.054, p=0.048) were also significantly related to ground-glass opacities. Positive effects of SHS were also detected on irregular/linear opacities.

SHS exposure in the last 12 months and over lifetime significantly increases ground-glass opacity in HRCT, suggesting an early or subclinical desquamative interstitial pneumonia/respiratory bronchiolitis. This study further supports that SHS has adverse effects on the lungs that can be detected by X-ray methods.