Science builds against BPA

With all of the new studies telling us time and again that bisphenol A (BPA) is bad for us, it can be easy to loose track of the latest facts.

An article in Science News takes a look at all the latest science surrounding BPA and explains what these studies can teach us.

Scientists are finding BPA affects a broad range of health issues, including women's reproductive health and heart health. These health conditions arise later in life, but they begin with the chemicals we are exposed to in the womb.

That's why the amount of BPA we are exposed to on a daily basis is also under close examination.

New studies are finding health effects in these areas:

Reproduction

According to Science News:

In one new study, researchers treated mice with BPA during the middle of their pregnancies. All female offspring of the treated mice suffered an irreversible genetic change in one of the “master regulatory genes” of fertility, Hugh Taylor of the Yale School of Medicine reported in June in Washington, D.C., at the annual meeting of the Endocrine Society.

This gene, HOXA10, orchestrates the activity of “hundreds — if not thousands — of downstream genes,” Taylor says. Through the genes it controls, HOXA10 helps synchronize the timing of uterine changes and ovulation. Without that synchrony, “you won’t get pregnancies,” he explains.

… Taylor says, “many diseases we see in adults owe their origins to fetal exposures” — when genes become inappropriately modified.

Heart health

In another study presented at the endocrine meeting, Scott Belcher of the University of Cincinnati and his colleagues reported that BPA boosted “pro-arrhythmic activity” in isolated muscle cells from mice and rats.

Arrhythmias, or heartbeat irregularities, are blamed for a higher mortality rate after heart attacks in premenopausal women compared with men, Belcher says.

During pregnancy, vulnerability to heart arrhythmias rises with higher estrogen levels. Belcher’s team found that in these cells, BPA’s effect on arrhythmia risk was nearly identical to estrogen’s.

In whole rat hearts exposed to BPA or estrogen, pockets of cells refused to beat in concert with others, his group showed, setting up potentially life-threatening arrhythmic events.

Exposure

But how much BPA are humans actually exposed to? That’s an issue of considerable debate, and the subject of another recent study. The Harvard School of Public Health recent measured the BPA levels in 77 students, first when they spent a week abstaining from using BPA-containing beverage containers, and then in a following week when the students only drank from polycarbonate containers. In the second week, BPA levels rose an average of 69 percent.

One long-held assumption has been that BPA disappears from the body 12-18 hours after it is ingested. But new studies are showing that the chemical stays in the body much longer.

In a National Health and Nutrition Examination Survey people were excreting as much BPA in their urine 12-20 hours after eating as they were just five hours after a meal. One hypothesis is that BPA may be stored in body fat before it is released back into the bloodstream.