About the Authors

Seung-Sup Kim

sskim@gwu.edu

Affiliation Department of Environmental and Occupational Health, The George Washington University School of Public Health and Health Services, Washington, D.C., United States of America

David R. Williams

Affiliation Department of Society, Human Development, and Health, Harvard School of Public Health, Boston, Massachusetts, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: S-SK DW. Analyzed the data: S-SK. Contributed reagents/materials/analysis tools: S-SK. Wrote the paper: S-SK DW.