A Meta-Analysis of Bladder Cancer and Diesel Exhaust Exposure

• Published in: Epidemiology (Cambridge, Mass.) Mass.), 2001-01, Vol.12 (1), p.125-130
• Main Authors: Boffetta, Paolo, Silverman, Debra T.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Bus drivers; Case control studies; Chemical and industrial products toxicology. Toxic occupational diseases; Diesel exhaust; Employment; Epidemiology; Europe - epidemiology; Gas, fumes; Humans; Medical sciences; Meta analysis; Mortality; Nephrology. Urinary tract diseases; Occupational Diseases - chemically induced; Occupational Diseases - epidemiology; Occupational Exposure - adverse effects; Review; Tobacco smoking; Toxicology; Truck drivers; Tumors of the urinary system; United States - epidemiology; Urinary bladder; Urinary Bladder Neoplasms - chemically induced; Urinary Bladder Neoplasms - epidemiology; Urinary tract. Prostate gland; Vehicle Emissions - adverse effects
• ISSN: 1044-3983; 1531-5487
• DOI: 10.1097/00001648-200101000-00021

The aim of this study is to review and summarize the available epidemiologic studies of bladder cancer and occupational exposure to diesel exhaust. We retrieved relevant studies and abstracted their characteristics and results. We assessed the heterogeneity of the results to decide whether to perform a fixed-effects model meta-analysis. We identified 35 relevant studies. No overall meta-analysis was performed because of heterogeneity in results. Results of railroad workers (N = 14) suggested an increased occurrence of bladder cancer, but we did not conduct a meta-analysis. The summary relative risk (RR) among truck drivers was 1.17 (95% confidence interval [CI] = 1.06-1.29, 15 studies) and that among bus drivers was 1.33 (95% CI = 1.22-1.45, 10 studies). Ten studies considered diesel exhaust exposure based on a job exposure matrix or a similar approach; the summary RR for these studies was 1.13 (95% CI = 1.00-1.27). A positive dose-response relation was suggested by 10 of the 12 studies that provided relevant information. The summary RR for high diesel exposure was 1.44 (95% CI = 1.18-1.76). There was some evidence of publication bias, however, with a lack of small studies with null or negative results. Our review suggests that exposure to diesel exhaust may increase the occurrence of bladder cancer, but the effects of misclassification, publication bias, and confounding cannot be fully taken into account.