Brown University toxicologists have found that male mice exposed to Bisphenol A (BPA), a chemical found in many plastic products, in the womb developed no signs of harm to their testes later in life.
Senior author Mary Hixon, assistant professor of pathology and laboratory medicine in the Warren Alpert Medical School of Brown University, and lead author Jessica LaRocca, a graduate student, exposed mice to BPA during days 10 through 16 of their pregnancy, the period of time when the sexual organs of their fetuses were developing.
Some pregnant mice consumed a solution with a concentration of BPA at the EPA-acceptable level, and other pregnant mice were given a solution at a concentration 20 times higher.
The experimenters’ negative controls were given sesame oil, and the positive controls were given diethylstilbestrol (DES), a much more potent estrogen-mimicking chemical.
The researchers then studied the litter size and viability of each mother’s pups and later studied several characteristics of the reproductive organs of their adult sons.
What they found is that by every measure at either dose level, the BPA did no apparent harm.
The litter sizes of BPA-exposed mothers were not affected compared to the negative control, both at birth and at weaning. In the adult male mice, testis weight, body weight, and seminal vesicle weight were no different.
The seminiferous tubules, sperm counts, and testosterone levels of BPA-exposed mice were also not significantly different.
The mice exposed to the chemical also did not show any abnormal amount of cell death among cells that make sperm or in the levels of mRNA associated with testis maturation.
“This might alleviate some worries for the general public. It comes down to the biology,” said Hixon.
The researchers hypothesize that the mothers and their growing sons are able to detoxify much of the BPA via their metabolism.
They, however, cautioned that while their study may offer some encouragement for male reproductive health to the extent it can be extrapolated from mice to men, it does not mean that BPA is harmless.
They said that the team did not test whether the sperm of BPA-exposed mice were actually fertile.
The finding appears in advance online in the journal Birth Defects Research (Part B).