Principal investigator Dr. De-Kun Li, a perinatal epidemiologist at the Kaiser Permanente Division of Research in Oakland, Calif., says the study population was identified from a larger study of more than 1,000 male and female workers in factories in China.
The researchers compared workers in BPA-exposing facilities with a control group of workers in factories where no BPA was present from 2003 to 2008.
Mothers in the exposed group worked for at least three months during pregnancy. Spouses of exposed fathers, although not directly exposed to BPA in the workplace, were more likely to have a higher BPA exposure level than women in the unexposed group -- possibly via contaminated clothing, workplace visits and through residence proximity to factories.
The study, published in the online issue Reproductive Toxicology, finds there was a greater magnitude of decrease in birth weight in children whose mothers were directly exposed to high BPA levels in the workplace during pregnancy, followed by those whose mothers were exposed to low levels of BPA in the workplace, then by those whose mothers had BPA exposure through father's high occupational BPA exposure.
The smallest decrease in birth weight was in offspring whose mothers had BPA exposure through fathers' low occupational exposure, the study says.