Meta-analyses of occupational exposure as a painter and lung and bladder cancer morbidity and mortality 1950–2008

Abstract

The International Agency for Research on Cancer (IARC) classified occupational painting as a human carcinogen based on lung and bladder cancers; however, no specific exposures were implicated. The authors conducted comprehensive meta-analyses of the epidemiological literature on occupational painting and these cancers. The authors abstracted study results and confounder information, and used quantile plots and regression models to evaluate heterogeneity and publication bias. Summary risk estimates were derived and sensitivity analyses performed to evaluate smoking, socioeconomic status (SES), and exposure variables. Where applicable, a Bayesian approach was used to externally adjust for smoking, a major risk factor for both cancers. For lung cancer cohort mortality studies, publication bias and heterogeneity were seen, and earlier studies reported higher risk estimates than later studies. Overall lung cancer summary risk estimates were 1.29 for case-control and 1.22 and 1.36 for cohort morbidity and mortality studies, respectively, and risk estimates for bladder cancer were 1.28 for case-control and 1.14 and 1.27 for cohort morbidity and mortality studies, respectively (all statistically significant). Risks did not differ between painters and mixed occupations. Nonsignificant summary estimates resulted for lung and bladder cancers when controlling for SES, or externally adjusting for smoking in lung cancer studies. Summary risks varied by control source for case-control studies. Residual confounding by smoking and SES, lack of exposure group effect, and publication bias limit the ability of the meta-analyses to explain associations observed between occupational painting and lung and bladder cancers. Given the long latencies for lung and bladder cancers, these weak associations, if real, may not be elucidated through studies of occupational painting today.

Keywords::

• Cancer risks
• confounding
• epidemiology
• painting
• review

Acknowledgements

We wish to acknowledge the valuable assistance of Ms. Renika Montgomery, MPH, in screening relevant studies considered in the meta-analyses and extracting data. We also are grateful to Ms. Melanie Kourbage for assistance with searches of the literature, to Ms. Mona Pion for obtaining articles, and to Mr. Stephen Sides of the International Paints and Printing Inks Council, Inc. (IPPIC) for his questions and comments on an early draft of this report.

Declaration of interest: Support for this work was provided by the International Paint and Printing Ink Council, Inc. Dr. Annette Bachand is a part-time employee of ENVIRON and Colorado State University. All other authors are full-time employees of ENVIRON International Corporation, a consulting firm providing services in environmental and health sciences matters to private firms, trade organizations, and government agencies. The authors carried out this work as a normal part of their employment activities. Except for Dr. K. Mundt, none of the authors has testified in any litigation or regulatory matter related to painting. Dr. K. Mundt recently testified at the request of Defense counsel in a litigation matter in which exposure to benzene and aromatic amines in a specific paint product were alleged; however, this case was dismissed as groundless when it was determined that these chemicals were not present. The authors have sole responsibility for the writing and content of the paper, which may not necessarily reflect the views of the International Paint and Printing Ink Council, Inc., which reviewed and provided comments on an earlier draft.