1. Department of Food Science and Human Nutrition Michigan State University East Lansing MI 48824 U.S.A
2. The Masonic Cancer Center University of Minnesota Minneapolis MN 55455 U.S.A
3. Division of Environmental Health Sciences University of Minnesota Minneapolis MN 55455 U.S.A
4. Department of Laboratory Medicine and Pathology University of Minnesota Minneapolis MN 55455 U.S.A
5. Department of Epidemiology and Biostatistics, College of Human Medicine Michigan State University East Lansing MI 48824 U.S.A