ETHYLENE-OXIDE EXPOSURE MAY INCREASE THE RISK OF SPONTANEOUS-ABORTION, PRETERM BIRTH, AND POSTTERM BIRTH

Ethylene oxide is a gas used in some dental offices to sterilize equip ment. In pregnant laboratory animals, ethylene oxide increases malform ations and fetal loss. Increased gestation length has also been report ed. In humans, two studies have reported increased spontaneous abortio ns among ethylene oxide-exposed women, but few other data exist. We se nt questionnaires to 7,000 dental assistants, age 18-39 years, registe red in California in 1987; 4,856 responded (69%). We based our analysi s on 1,320 women whose most recent pregnancy was conceived while worki ng full-time. Thirty-two women reported exposure to ethylene oxide; un exposed dental assistants comprised the comparison group. We estimated relative risks of spontaneous abortion and preterm birth using a pers on-week model. We estimated relative risks of postterm birth (greater than or equal to 42 weeks) and a combined adverse outcomes model using logistic regression. Among exposed women, the age-adjusted relative r isk of spontaneous abortion was 2.5 [95% confidence interval (CI) = 1. 0-6.3], for preterm birth 2.7 (95% CI = 0.8-8.8), and for postterm bir th 2.1 (95% CI = 0.7-5.9). The estimated relative risk of any of these adverse outcomes among exposed women was 2.5 (95% CI = 1.0-6.1) after adjusting for age, nitrous oxide, and number of mercury amalgams prep ared. These data further implicate ethylene oxide as a possible reprod uctive toxicant in humans.