BPA is a synthetic chemical that is the main component in polycarbonate, which ultimately forms the unbreakable plastic used in the food cans, water bottles, drink containers, compact discs, electronics and also baby bottles.
People around the world are facing a dilemma over deciding whether chemical bisphenol A, which is commonly known as BPA, is safe for them and their kids if used in low levels or not. Some experts say the chemical can pose threat to lives of human beings, while other say it's not that much harmful.
Echoing findings of the previous studies that suggested a link between BPA and human health problems, several new animal studies warn that BPA could impair the chances of successful in vitro fertilization, or the ability of embryos to attach to the uterus, and can cause arrhythmias, or irregular heartbeats, especially in women.
BPA's effect on heart
In one animal study, researchers found that estrogen and BPA caused heartbeat irregularities in heart cells isolated from rats and mice.
"Basically, it's very clear that BPA is acting like estrogen," said study co-author Scott Belcher, an associate professor of pharmacology at the University of Cincinnati. "If we give estrogen at physiological concentrations, then add BPA, it's actually a synergistic effect. It's not like adding the two together. It's worse."
Prior to menopause, women's "mortality rate after a heart attack is more than double that of men" and Belcher suspects an increased rate of arrhythmias could be the reason for the trend.
BPA affects fertility
In another study, researchers at Yale University warn that exposure to BPA might affect reproduction.
For the study, Hugh Taylor, MD, professor and chief of the reproductive endocrinology section at Yale University School of Medicine, and his colleagues exposed mice on days 9 to 16 of the animals' pregnancies to 5 milligrams of BPA per kilogram body weight. After the mice gave birth, the team analyzed the uterus of female offspring and extracted DNA.
The team noticed that BPA exposure during pregnancy had permanent and irreversible alterations in a gene known as HOXA10 that plays an important role in uterine development and the fertility of many animals, including humans.
"We don't know what a safe level of BPA is, so pregnant women should avoid BPA exposure," Taylor said. "There is nothing to lose by avoiding items made with BPA - and maybe a lot to gain."
BPA consumption more than estimated
A third study in monkeys hint that people may be getting higher-than-recommended exposure to BPA from both known and unknown sources.
Fresh results show that U.S. adults are exposed to more BPA from multiple sources than previously thought, said Frederick vom Saal, PhD, a co-author of the new study and a professor of biological sciences at the University of Missouri-Columbia. According to the National Institutes of Health, which funded the study, the chemical can leach into food and beverages.
"Between 8 and 9 billion pounds of BPA are used in products every year," vom Saal said.
For their study, vom Saal and his team administered an oral dose of BPA (400 micrograms per kilogram of body weight) to 5 female rhesus monkeys, an animal that the study authors say models human responses to hormones and hormone mimics.
The amount of BPA they administered to the animals was more than 400 times higher than the amount recommended by the U.S. Food and Drug Administration (FDA). The US health agency estimates typical daily human BPA consumption at roughly one microgram of BPA per kilogram of body weight.
Surprisingly, the blood levels of biologically active chemical over the next 24 hours were lower in the monkeys than the average levels found in U.S. adults, vom Saal said. That suggests that if these monkeys metabolize BPA at rates comparable to people, "humans would have to be exposed to over 1,000 µg/kg/day in order to achieve the kind of [blood] levels that are seen in multiple studies, not just the [German] one."
Reader Comments
to our Newsletter