Many cases of unexplained infertility could very well be linked to the plastic additive Bisphenol A (BPA), a new research from Brigham and Women’s Hospital (BWH) suggests. The scientists showed that BPA exposure could adversely affect egg maturation in humans.

Although this study was small and further research is warranted, the findings do raise red flags regarding the adverse health impact on female fertility.

“To our knowledge, this is the first study that has shown that BPA has a direct effect on egg maturation in humans,” stated Dr Catherine Racowsky, study lead author.

“Because exposure to BPA is so ubiquitous, patients and medical professionals should be aware that BPA may cause a significant disruption to the fundamentals of the human reproductive process and may play a role in unexplained infertility.”

Study details

The researchers examined 352 clinically discarded eggs from 121 consenting women who had enrolled in the IVF/ICSI program at BWH. One egg from each patient was used as control and was not exposed to BPA; the other eggs were subjected to varying levels of BPA in the lab.

The lowest dose, 20ng/ml, corresponds to levels that have been measured in human urine samples according to several national surveys conducted by the NIH (US).

Study findings

“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,” said Dr Racowsky.

The researchers found that exposure to BPA:

  • Impaired the eggs’ maturation – the percentage of eggs that attained full maturation dropped by a significant 50% with the lowest dose of BPA;
  • Caused an increase in the number of eggs that degenerated;
  • Led to more eggs being spontaneously activated, an abnormal condition where an egg behaves as if it is fertilised when it is not.

The researchers also discovered that as the exposure dose increased, there was an increased probability that the chromosomes would be misaligned and the spindles abnormally shaped. The spindles are involved in cell division; they separate the DNA.

Findings from previous studies

An earlier study conducted on monkeys revealed that BPA can damage chromosomes and cause miscarriages and birth defects by upsetting the female reproductive system.

Another laboratory study showed that exposure to low doses of BPA during pregnancy had immediate and long-lasting effects on the brain and behaviours of offspring. Some genetic changes even persisted into the fourth generation.

Exposure to BPA may also decrease male fertility by decreasing testosterone levels and sperm counts according to a study conducted on mice.

What you can do to decrease your exposure to BPA

  • Choose fresh/frozen fruits and veggies and dried beans/legumes over canned ones.
  • Select tomato-based products that come in cardboard or glass containers instead of cans – tomatoes are quite acidic and can cause more BPA from the cans to leach in the product.
  • Avoiding drinking water from plastic bottles and canned soft drinks and beers.
  • Do not heat plastics in microwaves.
  • Wear gloves or wash your hands regularly if you handle a lot of receipts.
  • Hand-wash plastic objects.

    Machtinger et al (2013) Bisphenol-A and human oocyte maturation in vitro. Hum Reprod. doi:10.1093/humrep/det312.

    Singh et al (2011) Effects of Bisphenol A on male mouse fertility. Endocr Rev. 32(03_MeetingAbstracts):P1-111.

    Wolstenholme et al (2012) Gestational exposure to bisphenol a produces transgenerational changes in behaviors and gene expression. Endocrinology. 153(8):3828-3838.