1. Departments of Obstetrics and Gynecology (R.S.L., J.G.P., C.L.G., W.C.D.), Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226-1998
2. Department of Public Health Sciences (A.R.K.), Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226-1998
3. Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033; and the Biomonitoring and Health Assessment Branch (J.W.M., J.S.K.), Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226-1998
4. Department of Pathology (R.J.Z.), Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226-1998
5. Department of Medicine (L.M.D.), Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226-1998