Author Contributions: Drs Zhang and Zhu had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Drs Rich, Kipen, and Huang contributed equally and are co-first authors of this article.
Study concept and design: Zhang, Kipen, Zhu, G. Wang, Y. Wang, Zhu, Ohman-Strickland, Lu, Hu, Thomas.
Acquisition of data: Wei, G. Wang, Y. Wang, P. Zhu, Gong, Hu, Zhang, Kipen, Rich.
Analysis and interpretation of data: Zhang, Kipen, Rich, Ohman-Strickland, Lu, Thomas, Diehl, Tong, Gong, Huang, Philipp.
Drafting of the manuscript: Rich, Kipen, Zhang, Ohman-Strickland.
Critical revision of the manuscript for important intellectual content: Rich, Kipen, Zhang, Ohman-Strickland, Thomas, Gong.
Statistical analysis: Ohman-Strickland, Lu, Tong, Gong.
Obtained funding: Zhang T. Zhu.
Administrative, technical or material support: Zhang, Zhu, G. Wang, Zhu, Y. Wang, Rich, Kipen, Huang, Hu, Tong, Gong.
Study supervision: Zhang, Kipen, G. Wang, Huang, Hu, T. Zhu, Rich.
Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
Funding/Support: This study was jointly funded by grants 1R01ES015864, P30ES005022, and 5P30ES007048 from the National Institute of Environmental Health Sciences, 4760-RPFA05-3 from the Health Effects Institute, OITC-G08026056 from the Beijing Environment Protection Bureau, and HB200504-6, HB200504-2 from the Beijing Council of Science and Technology.
Role of the Sponsors: None of the funding agencies had a role in the design and conduct of the study; in the collection, analysis, and interpretation of the data; or in the preparation, review, or approval of the manuscript.
Additional Contributions: We are indebted to the study participants for their commitment to the study and to the students and staff members at Peking University and Peking University First Hospital for their assistance with sample and data collection.