Report links BPA to breast cancer.
A growing number of health advocates are raising concerns about possible links between the estrogen-like chemical BPA and breast cancer.
Consumer concern about BPA, or bisphenol A, has led manufacturers to remove it from baby bottles and infant-formula packaging.
But BPA could also pose a risk to children long before they take their first sip of milk, according to a September report from the Breast Cancer Fund, an advocacy group, because babies are exposed in the womb.
A developing fetus is especially vulnerable during the first 11 weeks of pregnancy, says co-author Sharima Rasanayagam, director of science at the Breast Cancer Fund. "Everything is being developed" at this stage, she says. "The building blocks are being laid down for future health."
The report cites 60 animal and human studies that link prenatal BPA exposure to an increased risk of a variety of health problems, from breast cancer and prostate cancer to decreased fertility, early puberty, neurological problems and immune system changes.
In a September paper, too new to be included in the report, Tufts University's Ana Soto found that BPA increased the risk of mammary cancers in rats. In two studies of rhesus monkeys published last year, other researchers found that BPA disrupted egg development, damaged chromosomes and caused changes in the mammary gland that made animals more susceptible to cancer.
Made for hormone therapy
Soto says it's possible that prenatal BPA exposure makes fetuses more sensitive to estrogen, a hormone that drives the growth of most breast cancers. In that way, BPA could indirectly increase the risk of breast cancer later in life.
In 2011, the American Medical Association labeled BPA an "endocrine-disrupting agent" because of evidence suggesting that it disrupts the body's normal hormonal regulation.
"Every pregnant woman in America is exposed to many different chemicals in the environment," says Jeanne Conry, president of the American College of Obstetricians and Gynecologists.
More than 90% of Americans have BPA in their bodies, research shows. Ten studies have found BPA in fetal tissue, including umbilical cord blood, as well as in amniotic fluid, the Breast Cancer Fund report notes.
BPA was developed in the 1930s as an estrogen-replacement therapy. Researchers stopped developing BPA as an estrogen, however, because another synthetic hormone, DES, or diethylstilbestrol, was far more potent.
Conry says she's concerned that exposure to BPA could, like DES, change the way that a developing fetus reacts to estrogen for the rest of its life.
Millions of pregnant women took DES from 1941 to 1971 to prevent miscarriage, until studies found that women exposed to DES before birth had a high rate of rare vaginal cancers. Studies later linked DES to breast cancer as well.
While concern over BPA has led many manufacturers to stop using the chemical in plastic bottles, it remains widely used in other plastics -- such as bicycle helmets, eyeglasses, medical equipment and the linings of metal food cans. BPA is also found in the coatings on many cash register paper receipts.
Trying to take the BPA out
Since 2011, the Breast Cancer Fund has campaigned to persuade food companies to stop using BPA.
Campbell Soup last year announced that it will phase out BPA but has not yet announced when that will happen or what material it will use instead. Eden Foods has sold its beans in BPA-free cans since 1999. It now sells tomatoes in glass jars, which have lower levels of BPA than traditional cans.
The American Chemistry Council, an industry group, notes that BPA plays an important role in food safety because it "helps to extend a product's shelf life and protects food from contamination and spoilage."
"BPA is one of the most tested substances in use today, and regulatory agencies around the world have repeatedly found that the evidence does not show a connection between typical exposure levels and health effects or disease," says Jayne Morgan, chief medical officer at the American Chemistry Council.
The Food and Drug Administration's official statement on BPA says that it is "safe at the very low levels that occur in some foods. This assessment is based on review by FDA scientists of hundreds of studies."
However, the FDA also has expressed "some concern" about the potential effects of BPA on the brain, behavior, and prostate gland in children, both before and after birth. The FDA banned BPA in baby bottles in 2012, after most manufacturers had already stopped using it. Earlier this year, the FDA formally banned BPA in infant-formula packaging, also after formula manufacturers had already abandoned the chemical.
Manufacturers of metal cans say there's no clear evidence that BPA linings cause harm.
John Rost, chairman of the North American Metal Packaging Alliance, says that recent "studies, coupled with the extensive research on BPA that has been thoroughly reviewed by FDA and multiple international regulatory bodies, continue to reaffirm that the trace amounts of BPA found in metal food and beverage packaging does not represent a health risk to humans at any age or stage of development."
James H. Collins, AP
Leslie Smith, USA TODAY