Contribution of Long-Term Exposure to Outdoor Black Carbon to the Carcinogenicity of Air Pollution: Evidence regarding Risk of Cancer in the Gazel Cohort.

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From: Environmental Health Perspectives(Vol. 129, Issue 3)
Publisher: National Institute of Environmental Health Sciences
Document Type: Report
Length: 9,434 words
Lexile Measure: 1450L

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Abstract :

Background: Black carbon (BC), a component of fine particulate matter [particles with an aerodynamic diameter [less than or equal to] 2.5 [micro]m ([PM.sub.2.5])], may contribute to carcinogenic effects of air pollution. Until recently however, there has been little evidence to evaluate this hypothesis. Objective: This study aimed to estimate the associations between long-term exposure to BC and risk of cancer. This study was conducted within the French Gazel cohort of 20,625 subjects. Methods: We assessed exposure to BC by linking subjects' histories of residential addresses to a map of European black carbon levels in 2010 with back- and forward-extrapolation between 1989 and 2015. We used extended Cox models, with attained age as time-scale and time-varying cumulative exposure to BC, adjusted for relevant sociodemographic and lifestyle variables. To consider latency between exposure and cancer diagnosis, we implemented a 10-y lag, and as a sensitivity analysis, a lag of 2 y. To isolate the effect of BC from that of total [PM.sub.2.5], we regressed BC on [PM.sub.2.5] and used the residuals as the exposure variable. Results: During the 26-y follow-up period, there were 3,711 incident cancer cases (all sites combined) and 349 incident lung cancers. Median baseline exposure in 1989 was 2.65 [10.sup.-5]/m [interquartile range (IQR): 2.23-3.33], which generally slightly decreased over time. Using 10 y as a lag-time in our models, the adjusted hazard ratio per each IQR increase of the natural log-transformed cumulative BC was 1.17 (95% confidence interval: 1.06, 1.29) for all-sites cancer combined and 1.31 (0.93, 1.83) for lung cancer. Associations with BC residuals were also positive for both outcomes. Using 2 y as a lag-time, the results were similar. Discussion: Our findings for a cohort of French adults suggest that BC may partly explain the association between [PM.sub.2.5] and lung cancer. Additional studies are needed to confirm our results and further disentangle the effects of BC, total [PM.sub.2.5], and other constituents.

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Gale Document Number: GALE|A657071243