| Lung Cancer Risk after Exposure to Polycyclic Aromatic Hydrocarbons: A Review and Meta-Analysis Ben Armstrong,1 Emma Hutchinson,1 John Unwin,2 and Tony Fletcher1 1London School of Hygiene and Tropical Medicine, London, United Kingdom; 2Health and Safety Laboratory, Sheffield, United Kingdom Abstract
Typical polycyclic aromatic hydrocarbon mixtures are established lung carcinogens, but the quantitative exposure-response relationship is less clear. To clarify this relationship we conducted a review and meta-analysis of published reports of occupational epidemiologic studies. Thirty-nine cohorts were included. The average estimated unit relative risk (URR) at 100 µg/m3 years benzo[a]pyrene was 1.20 [95% confidence interval (CI) , 1.11-1.29] and was not sensitive to particular studies or analytic methods. However, the URR varied by industry. The estimated means in coke ovens, gasworks, and aluminum production works were similar (1.15-1.17) . Average URRs in other industries were higher but imprecisely estimated, with those for asphalt (17.5 ; CI, 4.21-72.78) and chimney sweeps (16.2 ; CI, 1.64-160.7) significantly higher than the three above. There was no statistically significant variation of URRs within industry or in relation to study design (including whether adjusted for smoking) , or source of exposure information. Limited information on total dust exposure did not suggest that dust exposure was an important confounder or modified the effect. These results provide a more secure basis for risk assessment than was previously available. Key words: cancer, lung, meta-analysis, PAH, polycyclics, review. Environ Health Perspect 112:970-978 (2004) . doi:10.1289/ehp.6895 available via http://dx.doi.org/ [Online 7 April 2004]
Address correspondence to B. Armstrong, London School of Hygiene and Tropical Medicine, Keppel St., London WC1E 7HT, U.K. Telephone: 44 0 207 927 2232. Fax: 44 0 207 580 4524. E-mail: ben.armstrong@lshtm.ac.uk The authors thank the Health and Safety Executive for financial support, the investigators of the included studies for providing additional information, and M. Stear for guidance on the exposure assessment. The authors declare they have no competing financial interests. Received 5 December 2003 ; accepted 7 April 2004.
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