Oct. 8, 2010 -- Pregnant women who work as cashiers, are exposed to tobacco smoke, or eat lots of canned veggies may have higher urinary levels of the controversial chemical bisphenol A (BPA), according to a new study. These levels tended to ebb and flow throughout pregnancy, according to the study, which appears in Environmental Health Perspectives.

Exactly how these findings pertain to the health of pregnant women and the developing fetus is not known. Some preliminary studies have suggested that higher levels of BPA may be associated with certain childhood behavior issues as well as obesity. The FDA has called for more study on BPA, citing "potential health concerns."

Many manufacturers have already taken steps to eliminate the BPA in baby bottles and cups, but this chemical is also found in the linings of canned foods, cigarette filters, and in certain "carbonless" receipts, where it coats paper to prevent ink smears.

"There has been a lot of effort to reduce exposure in children's products, whether toys or baby bottles, but fetuses can also be vulnerable to these toxins. So if we are really concerned about exposure, we need to reduce exposure during the fetal period as well," says study researcher Joe M. Braun, PhD, a research fellow in the department of environmental health at the Harvard School of Public Health in Boston.

Researchers measured BPA levels in the urine of 386 pregnant women at 16 weeks, 26 weeks, and again within a day of delivery. Ninety percent of women had detectable levels of BPA in their urine at 16 weeks and 26 weeks, and 87.1% had detectable BPA at delivery. Because of its ubiquitous nature, BPA can be detected in the bodies of about 90% of people in the U.S.

Specifically, women exposed to tobacco smoke had BPA concentrations that were about 20% higher than women who were not exposed. Working as a cashier was the occupation associated with the highest BPA concentrations in the study (2.8 nanograms/milliliter urinary concentration), but there were only 17 cashiers included.

Women who reported eating canned vegetables (but not canned fruits) once a day had higher urinary BPA levels than their counterparts who did not eat as many canned veggies, (2.3 nanograms/milliliter urinary concentration vs. 1.6 nanograms/milliliter urinary concentration, respectively.) Pregnant women who were also exposed to phthalate-containing products such as some vinyl flooring and plastic containers, women with less than 12 years of education, and women who earned less than $20,000 per year also had higher BPA levels in their urine. Phthalates are chemicals used to soften vinyl and other plastics.
Avoid BPA in Pregnancy

"There are behaviors that women have that have a significant influence on the BPA in their bodies when pregnant," says Laura N. Vandenberg, PhD, of the department of biology at Tufts University in Boston. Smoking and exposure to secondhand smoke should be avoided during pregnancy, she says. "Reducing canned food use may have an impact on the BPA in the body," she says. It is too early to make any recommendations regarding receipts, she says.

Fred vom Saal, PhD, a professor of reproductive biology and neurobiology at the University of Missouri in Columbia, is less cautious in his BPA avoidance recommendations. "The exposure levels seen in pregnant women in this study could be placing them and their developing fetus in harm’s way," he says.

He suggests steering clear of canned foods unless and until manufacturers eliminate the BPA in their liners. When shopping, "if you don't have to touch the receipt, ask the cashier to throw it away for you," he says, adding that this is something he practices.

Not so fast, says Gilbert Ross, MD, medical director for the American Council on Science and Health, a New York City-based consumer education group. Ross takes issue with the new study findings and says that they do little to advance what is known about BPA and human health.

"Pregnant women excrete tiny, tiny amounts of BPA in their urine, at a variable rate over a day, he says. " These tiny amounts play absolutely no role in their health, nor that of their fetuses and newborns."