When scientists exposed pregnant mice to levels of bisphenol A (BPA), equivalent to what is acceptable for humans, three generations of mice experienced reduced fertility. While we know that bisphenol A can impact the fertility of animals, its effect on various generations is startling.
Pregnant mice that were exposed to BPA had pups with declined fertility, delayed sexual maturity, and difficulty carrying babies to term, according to a study published in the journal of Toxicology and Applied Pharmacology. While mice and humans are certainly different species, the fact that in a recent survey, 93 percent of human urine samples showed detectable levels of BPA, is rather disconcerting.
"Our study followed up on a previous study of ours that found that BPA can affect the development of the ovary and reduce fertility in the pups of pregnant mice exposed to the chemical," University of Illinois comparative biosciences professor Jodi Flaws, who led the new analysis said to Medical XPress. "We found that exposing them to levels of BPA which are below what the U.S. Food and Drug Administration says is a safe dose causes reproductive problems in these mice."
BPA is an epoxy resin that’s used in the lining of aluminum cans, cash register receipts, plastic bottles, and other types of food packaging. It’s also found in toys and other hard plastic products. BPA has been linked to a number of health problems because it mimics estrogen in the body, sending false hormone signals. It’s been linked to breast and prostate cancer, declines in sperm counts, obesity, type 2 diabetes, and a host of other health ailments.
In this particular study, BPA seemed to impact the mice's ability to get pregnant and carry a baby to term. In the second generation of mice, pups did not engage in typical mating behavior while in the third generation, which had not directly been exposed to BPA, pups experienced later sexual maturity, reduced fertility, and lower pregnancy success.
"There are a lot of studies out there, and when you look at BPA in women's reproductive health, there are a lot of consistencies with the animal studies," she said to Medical Xpress. "Many of the studies in women have been done by Dr. Russ Hauser at Harvard. He has shown that urinary concentrations of BPA were associated with reduced fertility and women's ability to get pregnant. So I personally think there is pretty good evidence that BPA is a reproductive toxicant in mice as well as in humans."
Another recent study at the University of Missouri found that BPA can alter a painted turtle’s reproductive system and disrupt sexual differentiation.
“Normally, the painted turtle’s sex is determined by the temperature of the environment during their development in the egg—cooler temperatures yield more male turtles, while warmer temperatures mean females are more likely to develop,” said Dawn Holliday, adjunct assistant professor of pathology and anatomical sciences in the MU School of Medicine and assistant professor of biology at Westminster College in Fulton, Mo. “However, when turtle eggs are exposed to environmental estrogens, their sex is no longer determined by the temperature, but rather by the chemical to which they’re exposed.”
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