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 Low-level exposure in the womb to the plastic chemical bisphenol A (BPA) can harm testicular function into adulthood, according to a new study from Auburn University that adds to the growing list of concerns about the ubiquitous chemical. The results were presented yesterday at The Endocrine Society's 92nd Annual Meeting.
"We are seeing changes in the testis function of rats after exposure to BPA levels that are lower than what the FDA and EPA consider safe exposure levels for humans," said Benson Akingbemi, the study's lead author. "This is concerning because large segments of the population, including pregnant and nursing mothers, are exposed to this chemical."
BPA, found in many plastic products such as drink bottles, acts in a similar manner as the female sex hormone estrogen and has been linked to female infertility. It is present in placental tissue and is able to pass from a mother into her breast milk.
In the new study, Akingbemi and colleagues saw the effects of BPA at the cellular level; specifically in Leydig cells (Leydig cells are responsible for testosterone secretion). Akingbemi explained that the process of testosterone secretion was decreased in the male offspring of female rats that received BPA during pregnancy and while nursing.
For the study, the mothers were fed BPA in olive oil at a dose of either 2.5 or 25 micrograms of BPA per kilogram of body weight. The daily upper limit of safe exposure for humans, according to federal guidelines, is 50 micrograms per kilogram of body weight. A control group of pregnant rats received olive oil without BPA.
The investigators then studied the development of Leydig cells in the male offspring. The capacity for testosterone secretion was assessed at 21, 35 and 90 days of age. The amount of testosterone secreted per Leydig cell was found to be much lower in male offspring after early-life exposure to BPA than in offspring from control unexposed animals.
"Although BPA exposure stopped at 21 days of age, BPA's effects on Leydig cells, which were seen immediately at the end of exposure and at 35 days, remained apparent until 90 days of age, when the rats reached adulthood," Akingbemi said. "Therefore, the early life period is a sensitive window of exposure to BPA and exposure at this time may affect testis function into adulthood."
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