A review of adverse pregnancy outcomes and formaldehyde exposure in human and animal studies

We examine the potential for reproductive and developmental effects from fo rmaldehyde exposure. Formaldehyde is unlikely to reach the reproductive sys tem in humans in concentrations sufficient to cause damage since it is rapi dly metabolized and detoxified upon contact with the respiratory tract. Whi le there are effects seen in in vitro studies or after injection, there is little evidence of reproductive or developmental toxicity in animal studies under exposure levels and routes relevant to humans. Most of the epidemiol ogy studies examined spontaneous abortion and showed some evidence of incre ased risk (meta-relative risk = 1.4, 95% CI 0.9-2.1). We found evidence of reporting biases and publication biases among the epidemiology studies and when these biases were taken into account, we found no evidence of increase d risk of spontaneous abortion among workers exposed to formaldehyde (meta- relative risk = 0.7, 95% Cl 0.5-1.0). The small number of studies on birth defects, low birth weight, and infertility among formaldehyde workers; the limitations in the design of these studies; and the inconsistent findings a cross these studies make it difficult to draw conclusions from the epidemio logy data alone. However, information from experimental studies and studies of metabolism indicate reproductive impacts are unlikely at formaldehyde e xposures levels observed in the epidemiology studies. (C) 2001 Academic Pre ss.