The chemical in your baby's bottle
WE LIVE in a chemical stew. So pervasive are the chemicals in the food we eat, in the products we use to keep our bodies, clothes, and houses clean, and in keeping our lawns manicured that it has become impossible to avoid them. We are surrounded by chemicals. Over 80,000 are in use and an additional 1,000-2,000 are introduced each year; however, only about 2 percent are tested by regulatory agencies for safety.
One chemical that has received a lot of attention lately is Bisphenol A, or BPA, an ingredient in plastics used to make reusable food and beverage containers (including baby bottles). It also coats the insides of food and beverage cans. Humans come in contact with it mainly through eating, but inhalation and absorption through the skin have not been ruled out. Regular exposure to BPA, including among infants and children, is shown by its presence in blood, amniotic fluid, umbilical cords, and breast milk. Additionally, the US Centers for Disease Control and Prevention detected BPA in the urine of 92.6 percent of the more than 2,500 Americans examined; levels were higher in children and adolescents than adults.
While BPA has its benefits, like preventing interactions between food items and metal cans, it has the biological actions of the female hormone estrogen. Why should we worry about that? Exposure to estrogenic chemicals during the time when our organs are developing, specifically during the fetal and neonatal periods and puberty, is a risk factor for breast and prostate cancers, malformations of reproductive organs, infertility, and alterations in brain development.
BPA was originally synthesized in 1891; in the 1930s it was considered for pharmaceutical use because of its estrogenic properties but was abandoned when diethylstilbestrol (DES) was found to be a more potent synthetic estrogen. DES was prescribed to at least 2 million women to prevent miscarriage under the assumption that during pregnancy "some estrogen is good, so more must be better." By 1971, girls exposed to DES in the womb had developed an extremely rare vaginal cancer typically found in elderly women. This caused the Food and Drug Administration to ban its use by pregnant women.
We often hear: "But we're all exposed to BPA and we've turned out fine." Unfortunately this isn't true. Since the chemical revolution when BPA and hundreds of other common chemicals containing hormonal agents were added to our lives, the incidence of many diseases and disorders has been on the rise, including early puberty, obesity, reduced sperm count, hyperactivity, genital malformations, breast cancer and prostate cancer. BPA has caused all of these in laboratory animals. Last year, a study of 1,455 adults, published in The Journal of the American Medical Association, showed a positive correlation between urinary BPA levels and diabetes and heart disease.
BPA is regulated by the US Environmental Protection Agency, which considers 50 parts per million of BPA per day to be a safe dose. However, over 100 animal studies have found effects well below this dose. In fact, scientists have yet to find a harmless dose of BPA.
Why hasn't BPA been banned? Mostly because BPA exposure cannot be associated with a single disease; the effects can be subtle and complications may appear years later. Animal studies revealed that BPA exposure during gestation contributed to behavioral disorders, obesity, diabetes, early puberty, breast cancer, prostate cancer, and infertility. In 2007, 38 international specialists on BPA signed the Chapel Hill Consensus Statement at a meeting organized by the National Institutes of Environmental Health Sciences: Such a wide range of harmful effects, though found in laboratory animals, provided "great cause for concern" for "the potential for similar adverse effects in humans." Experts at the National Toxicology Program agreed.
It is now up to federal and state regulatory agencies, including the Massachusetts Department of Public Health, to stop ignoring the government-funded studies showing that BPA exposure can contribute to a variety of chronic diseases. A new set of policies should eliminate BPA from products that expose our most vulnerable populations: fetuses, infants, and children.
Laura N. Vandenberg and Maricel V. Maffini are research scientists at Tufts University.