Pregnant women who eat canned vegetables daily have elevated levels of bisphenol A, an estrogenic chemical found in food containers and other consumer products, according to new research published today.

More than 90 percent of pregnant women had detectable levels of bisphenol A, and a variety of sources of the chemical were identified in the study. Pregnant women who were exposed to tobacco smoke or worked as cashiers also had above-average concentrations in their bodies.

Bisphenol A, or BPA, is an estrogen-mimicking chemical used in food and beverage can linings, polycarbonate plastic and cash register receipts. Lab animals exposed in the womb to low amounts of BPA develop prostate and mammary gland cancers, obesity and reproductive problems. In humans, BPA has been linked to heart disease and diabetes.

A few years ago, many mothers reacted strongly to protect their infants from BPA by pressuring retailers and manufacturers to offer BPA-free baby bottles. But the new study shows that pregnant women are still unwittingly exposing their infants during fetal development, which is an even more vulnerable time.

“This really highlights that there are a lot of sources of BPA exposure during pregnancy,” said Joe Braun, a research fellow at the Harvard School of Public Health and lead author of the study conducted by scientists from seven institutions. “This identifies some sources that are modifiable, meaning that women can actually lower their exposures to them.”

The researchers tested the urine of 386 pregnant women in the Cincinnati area who delivered babies between 2003 and 2006. One woman was excluded because her BPA levels were extraordinarily high – 1,000 times higher than the group’s median.