Experts are finding that exposure to bisphenol A (BPA)—an additive used in numerous products, but most commonly found in plastic water bottles, cash register receipts, and soup can liners—may be affecting human health more than we know.
Last year, the U.S. Food and Drug Administration (FDA) said BPA was safe for people of all ages, yet banned the use of the chemical in sippy cups, baby bottles, and other containers used by children.
Prior research on BPA, which acts like synthetic estrogen in the body, has been linked to miscarriages and birth defects in primates, as well as to behavioral problems in girls, impotence in men, an increased risk of heart disease, and other health problems.
Three studies that link BPA to even more health problems, including birth defects and cancer in animal testing, were presented during The Endocrine Society’s annual meeting this week in San Francisco.
BPA Linked to Increased Cancer Risk
Early exposure to BPA increases a person’s risk of developing prostate cancer, according to research by Gail Prins, a professor of physiology at the University of Illinois at Chicago.
Prins tested daily levels of BPA exposure in animal models and found that BPA’s estrogen effect “reprograms” prostate stem and progenitor cells.
Prins arrived at her conclusion by implanting prostate stem cells from dead male organ donors into mice. The cells formed human prostate tissue, and Prins fed the mice doses of BPA similar to those found in previous studies of pregnant American women. After one month, signs of cancer developed in a third of the mice fed BPA, nearly three times the rate of cancer in the mice not given BPA.
“This is the first direct evidence that exposure to BPA during development, at the levels we see in our day-to-day environment, increases the risk for prostate cancer in human prostate tissue,” Prins said in a press release accompanying the research.
BPA May Affect Undescended Testicles
French researchers have linked BPA exposure to defects in a testicular hormone in babies with undescended testicles, a condition that affects up to five percent of full-term newborns.
Lead study author Dr. Patrick Fenichel, the head of reproductive endocrinology at the University Hospital of Nice in France, and others studied 180 boys, 26 of whom had undescended testicles at 3 months of age. Testing the infants' umbilical cord blood, the researchers measured levels of BPA and peptide 3, a hormone that aids in the descent of the testicles.
Researchers found that infants with higher BPA levels in their blood also had lower levels of peptide 3 hormones. Fenichel speculated that estrogen-like BPA affected peptides in humans in the same way it did in animal trials, meaning that BPA levels could impact testicle descent, but more research is needed to confirm this theory.
BPA May Increase the Risk of Obesity
Researchers also say prenatal exposure to BPA may lead to inflammation in fat tissue, increasing a person’s chances of being obese later in life.
Researchers at the University of Michigan at Ann Arbor fed two groups of pregnant sheep corn oil, one with nothing added and another with added BPA up to the level found in human umbilical cord blood. When they were born, half of the lambs in each group were overfed. After seven months, the sheep whose mothers were fed BPA and a normal diet had increased biomarkers for obesity and metabolic syndrome.
“This research is the first study to show that prenatal exposure to BPA increases postnatal fat tissue inflammation, a condition that underlies the onset of metabolic diseases such as obesity, diabetes, and cardiovascular disease,” lead author Almudena Veiga-Lopez said in a press release.
The researchers chose sheep because their body fat is similar to that of humans.