1. Department of Community Medicine, West Virginia University, Morgantown, West Virginia, USA
2. Department of Epidemiology and Biostatistics, State University of New York at Albany, Rensselaer, New York, USA
3. Bureau of Occupational Health, New York State Department of Health, Troy, New York, USA
4. Bureau of Environmental and Occupational Epidemiology, New York State Department of Health, Troy, New York, USA