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Review Advance Publication

Environ Health Perspect; DOI:10.1289/ehp.1408092

Outdoor Particulate Matter Exposure and Lung Cancer: A Systematic Review and Meta-Analysis

Ghassan B. Hamra,1 Neela Guha,1 Aaron Cohen,2 Francine Laden,3,4 Ole Raaschou-Nielsen,5 Jonathan M. Samet,6 Paolo Vineis,7 Francesco Forastiere,8 Paulo Saldiva,9 Takashi Yorifuji,10 and Dana Loomis1
Author Affiliations close
1International Agency for Research on Cancer. Lyon, France; 2Health Effects Institute. Boston, Massachusetts, USA; 3Channing Division of Network Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, USA; 4Departments of Environmental Health and Epidemiology, Harvard School of Public Health. Boston, Massachusetts, USA; 5Institute of Cancer Epidemiology, Danish Cancer Society, Copenhagen, Denmark; 6Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, USA; 7Department of Epidemiology and Public Health, Imperial College London, London, United Kingdom; 8Department of Epidemiology, Regional Health Authority, Lazio, Roma, Italy; 9Department of Pathology, School of Medicine, University of São Paulo, São Paulo, Brazil; 10Department of Human Ecology, Graduate School of Environmental and Life Sciences, Okayama University, Okayama, Japan
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This EHP Advance Publication article has been peer-reviewed, revised, and accepted for publication. EHP Advance Publication articles are completely citable using the DOI number assigned to the article. This document will be replaced with the copyedited and formatted version as soon as it is available. Through the DOI number used in the citation, you will be able to access this document at each stage of the publication process.

Citation: Hamra GB, Guha N, Cohen A, Laden F, Raaschou-Nielsen O, Samet JM, Vineis P, Forastiere F, Saldiva P, Yorifuji T, Loomis D. Outdoor Particulate Matter Exposure and Lung Cancer: A Systematic Review and Meta-Analysis. Environ Health Perspect;

Received: 6 January 2014
Accepted: 3 June 2014
Advance Publication: 6 June 2014

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Background: Particulate matter (PM) in outdoor air pollution was recently designated a Group I carcinogen by the International Agency for Research on Cancer (IARC). This determination was based on the evidence regarding the relationship of PM2.5 and PM10 to lung cancer risk; however, the IARC evaluation did not include a quantitative summary of the evidence.

Objective: To provide a systematic review and quantitative summary of the evidence regarding the relationship between PM and lung cancer.

Methods: We conducted meta-analyses of studies examining the relationship of exposure to PM2.5 and PM10 with lung cancer incidence and mortality. In total, 18 studies met inclusion criteria and provided the information necessary to estimate the change in lung cancer risk per 10-μg/m3 increase in exposure to PM. We used random effects analyses to allow between study variability to contribute to meta-estimates.

Results: The meta-relative risk (95% CI) for lung cancer associated with PM2.5 was 1.09 (95% CI: 1.04, 1.14). The meta-relative risk of lung cancer associated with PM10 was similar, but less precise: 1.08 (95% CI: 1.00, 1.17). Estimates were robust to restriction to studies that considered potential confounders, as well as sub-analyses by exposure assessment method. Analyses by smoking status showed that lung cancer risk associated with PM2.5 was greatest for former smokers, 1.44 (95% CI: 1.04, 1.22) followed by never smokers, 1.18 (95% CI: 1.00, 1.39), and then current smokers, 1.06 (95% CI: 0.97, 1.15). In addition, meta-estimates for adenocarcinoma associated with PM2.5 and PM10 were 1.40 (95% CI: 1.07, 1.83) and 1.29 (95% CI: 1.02, 1.63), respectively.

Conclusion: The results of these analyses, and the decision of the IARC working group to classify PM and outdoor air pollution as carcinogenic (Group 1), further justify efforts to reduce exposures to air pollutants that can arise from many sources.

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