Author Contributions: Dr Chapman had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Chapman, Li, Colby, Yoon.
Acquisition of data: Chapman, Li.
Analysis and interpretation of data: Chapman.
Drafting of the manuscript: Chapman.
Critical revision of the manuscript for important intellectual content: Li, Colby, Yoon.
Statistical analysis: Chapman.
Administrative, technical, or material support: Li, Colby, Yoon.
Study supervision: Chapman.
Financial Disclosures: None reported.
Additional Contributions: We acknowledge the cooperation and support of the staff in the Rutgers Department of Occupational Health. They did not receive additional compensation for their contributions.