LaRocca and Hixon hypothesize that the mothers and their growing sons are able to detoxify much of the BPA via their metabolism, an important reason to test BPA exposure via the digestive system, the most common route of exposure to humans. BPA, which has been used in baby bottles and to line soda cans, leaches into the liquids people drink.
"So while the [mother] has the dose of 50 micrograms per kilogram, by the time it reaches the fetus that dose is much, much lower than if you were to inject the animal," LaRocca said.
"Humans are not going to get the exposure the animals were exposed to," Hixon added.
But by this ingestion method the researchers did find several negative effects of exposure to DES, a synthetic estrogen prescribed from the late 1930s to the early 1970s in hopes of preventing pregnancy complications. In the mice, DES significantly reduced litter size and steroidogenesis mRNA expression.
And the females?
Hixon and LaRocca 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.
Hixon noted that the research team did not test whether the sperm of BPA-exposed mice were actually fertile.
More concerning is their data on the reproductive development of the female mouse pups born in the study. Although that analysis is more preliminary and still unpublished, it shows signs of lasting negative effects of BPA exposure in their mammary glands and ovaries.
In addition to Hixon and LaRocca, other authors on the paper include Alanna Boyajian, Caitlin Brown, and Stuart Duncan Smith.
|Contact: David Orenstein|