1. Department of Preventive Medicine, The Catholic University of Korea, Seoul, Korea
2. Laboratory of Clinical and Experimental Endocrinology and Immunology, Wadsworth Center, New York State Department of Health, Albany, New York, NY 1220 USA
3. Korean Industrial Health Association, Suwon, Korea
4. Laboratory of Clinical and Experimental Endocrinology and Immunology, Wadsworth Center, New York State Department of Health, Albany, New York, NY 1220 USA; Wadsworth Center, New York State Department of Health, P.O. Box 509, Albany, NY 12201-0509 USA