Reproductive outcomes of pregnant workers employed at 36 reinforced plastics companies. II. Lowered birth weight.

The authors analyzed the birth weights of infants whose mothers worked during pregnancy in the reinforced plastics industry, where styrene monomer is a primary chemical exposure. Reproductive and work histories were taken by telephone interview from 1535 women employed between 1974 and 1981 at 36 companies. The questionnaire was based on one used by the National Institute for Occupational Safety and Health, and indices of styrene exposure were derived from an historical set of 1500 industrial hygiene samples from the study companies. There was not a significant dose-response trend in decreasing average birth weights. However, women who worked at the most highly exposed jobs--such as laminators, rollers, or spray-up operators at boat manufacturing companies--had offspring with adjusted birth weights of 4% less than the offspring of unexposed women (95% confidence interval = -7.7% to +0.6%) after adjustment for other factors.