A new study from Brigham and Women’s Hospital (BWH) recently analyzed the effects of Bisphenol-A (BPA) on human eggs, and it may reveal why some couples are unable to conceive.

The study, published recently online in the journal Human Reproduction, is the first of its kind to show the direct effects of BPA on egg maturation in humans.

BPA is a chemical that is used to make certain plastics and resins, and it can be found in some water bottles, food cans, bottle tops or water supply lines.

The experiment was led by Dr. Catherine Racowsky, director of the Assisted Reproductive Technologies Laboratory at BWH. She and her team conducted a randomized trial using 352 discarded eggs from 121 patients, who were undergoing in vitro fertilization (IVF) at the hospital from 2011 to 2012.

Subjects’ eggs were exposed to varying levels of BPA in the laboratory, but an egg from each patient was held aside and not exposed to BPA to serve as the control.

After being exposed to BPA, researchers examined the eggs and found the following results:

  • Percentage of eggs that matured decreased
  • Proportion that degenerated fell
  • Percentage of eggs that underwent spontaneous activation increased
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Genetic parts of eggs exposed to BPA (images B, C, D, E) compared with unexposed eggs (A). In green: spindles. Red: chromosomes. Right: combination of both. Courtesy of Brigham and Women’s Hospital

(Spontaneous activation is an abnormal process in which an unfertilized egg acts as if it has been fertilized.)

Researchers also noticed with eggs that did mature, they tended not to have bipolar spindles and aligned chromosomes, as unaffected eggs do.

Dr. Racowsky says:

Our data show that BPA exposure can dramatically inhibit egg maturation and adds to a growing body of evidence about the impact of BPA on human health.

I would encourage further research to gain a greater understanding of the role BPA plays in infertility.”

The researchers note that the prevalence of BPA in our society is such that the general population is exposed to it on a regular basis. They also say that BPA has been detected in human follicular fluid.

Katherine Zeratsky from the Mayo Clinic notes that although the Food and Drug Administration (FDA) says BPA is safe at very low levels, the organization is continuing to review BPA and supports ongoing research.

She makes a few recommendations for those consumers who are concerned about BPA, including:

  • Use BPA-free products
  • Cut back on cans
  • Avoid microwaving or dishwashing plastics.

Researchers from the recent study note that though they “used sibling oocytes (eggs) to overcome potential confounders, such as infertility diagnosis and maternal age, additional studies with a larger number of oocytes are required to confirm present results.”