A new animal study has found that a mothers' exposure to the chemical bisphenol A (BPA) may make offspring prone to a fertility defect. The chemical is found in commonly available plastic household items like plastic cans and bottles.
In fact, the study has now revealed how the defect actually occurs.
BPA is used to make hard polycarbonate plastic, such as for baby bottles, refillable water bottles and food containers, as well as to make the linings of metal food cans.
BPA has oestrogen-like properties and has been linked to female infertility in pregnant animals.
"The big mystery is how does exposure to this oestrogen-like substance during a brief period in pregnancy lead to a change in uterine function," said study co-author Dr. Hugh Taylor at Yale University School of Medicine.
Thus, the researchers injected pregnant mice with a low dose of BPA on pregnancy days 9 to 16. fter the mice gave birth, the scientists analysed the uterus of female offspring and extracted DNA.
They found that BPA exposure during pregnancy had a lasting effect on one of the genes that is responsible for uterine development and subsequent fertility in both mice and humans (HOXA10).
In addition, these changes in the offspring's uterine DNA resulted in a permanent increase in oestrogen sensitivity.
According to the authors, the process causes the overexpression of the HOXA10 gene in adult mice that they found in previous studies.
However, the permanent DNA changes in the BPA-exposed offspring were not visible in the offspring of mice that did not receive BPA injection.
Taylor said that the finding demonstrates that the foetus is sensitive to BPA in mice and likely also in humans.
"We don't know what a safe level of BPA is, so pregnant women should avoid BPA exposure. There is nothing to lose by avoiding items made with BPA-and maybe a lot to gain," said Taylor.
The results of the new study will be presented at The Endocrine Society's 91st Annual Meeting in Washington, D.C.