American Journal of Industrial Medicine zyx 28:751-769 (1995) Historical Cohort Study of Spontaneous Abortion Among Fabrication Workers in the Semiconductor Health Study: Agent-Level Analysis Shanna H. Swan, PhD, James J. Beaumont, PhD, S. Katharine Hammond, PhD, Julie VonBehren, MPH, Rochelle S. Green, MS, Marilyn F. Hallock, MS, Susan zyxwvut R. Woskie, PhD, Cynthia J. Hines, MS, and Marc B. Schenker, MD, MPH Risk of spontaneous abortion (SAB) was examined in relation to chemical and physical agents in a retrospective study of employees of 14 seminconductor manufacturers: After screening over 6,000 employees, 506 current and 385 former workers were eligible. If a woman had multiple eligible pregnancies, one was selected at random. Telephone interviews provided data on demographics and occupational and other exposures during the first trimester. Two groups of chemicals accounted for the 45% excess risk of SAB among fabrication-room (fab) workers: photoresist and developed solvents (PDS), in- cluding glycol ethers, and fluoride compounds used in etching. Women exposed to high levels of both these agents were at greater risk (RR zyxwv = 3.21. 95% confidence interval zy [CI] = 1.29-5.96). In fab workers without these exposures, SAB rates were not elevated (adjusted relative risk [RR] = 0.98. 95% C1 = 0.55-1.69). An association was seen with workplace stress, which was not limited to women exposed to PDS or fluoride, nor did stress explain the associations between these chemicals and SAB. zy 0 1995 Wiley-Liss. Inc. Key words: semiconductor manufacturing, glycol ethers, fluoride, stress, spontaneous abortion. miscarriage occupational exposures INTRODUCTION Several epidemiologic studies were conducted following the report of an asso- ciation between fabrication-room (fab) processes in a semiconductor manufacturing Department of Epidemiology, School of Public Health. University of California. Berkeley (S.H.S., J.V.). Division of OccupationallEnvironmental Medicine and Epidemiology, Department of Internal Medicine. School of Medicine, and Institute of Toxicology and Environmental Health, University of California, Davis (J.J.B., R.S.G., M.B.S.). Environmental Health Division, Department of Family and Community Medicine, University of Massa- chusetts Medical Center, Worcester (S.K.H., S.R.W.). Massachusetts Institute of Technology, Cambridge (M .F.H.). Center for Occupational and Environmental Health. School of Public Health, University of California, Berkeley (C.J. ti.). Address reprint requests to Shanna H. Swan, PhD, Department of Epidemiology, School of Public Health. University of California, Berkeley, CA 94720. Accepted for publication May I, 1995. 8 1995 Wiley-Liss, Inc.