Researchers found exposure to plastics containing bisphenol A (BPA) and birth control chemicals found in drinking water can decrease one's sperm count.
The findings could provide a cause behind previously unsolved cases of decreases sperm count seen in many human studies, and could also support the popular "estrogen hypothesis" associated with the chemical, Washington State University reported.
"This provides some real insight into what exactly might be going on," said WSU geneticist and principle investigator Pat Hunt. "It's kind of bizarre because we got into it through a back door, not really starting out to look at that question."
BPA is often found in plastic bottles, food cans, and on thermal receipts. In the 1990s researchers reported a "genuine decline in semen quality over the past 50 years," and this new research suggests BPA could be playing a role in the phenomenon.
To make their findings the researchers gave newborn male mice oral doses of BPA and exposed the to the synthetic estrogen ethinyl estradiol (which is used in birth control and passes through sewage plants untreated). The team found the exposed mice's sperm did a poorer job at meiosis, which is the process where cells combine genetic information with their parents. They found this occurrence lead to higher rates of sperm death.
"This mouse model would suggest that here's actually a reason why these sperm counts would be falling," Hunt said. "We're actually doing something to this process that's going to cause the death of more cells as they're trying to make sperm. They're going to get culled out by this quality-control mechanism and the upshot of that will be that if you do enough of this, you'll drop sperm counts."
The researchers noted they believed estradiol has an even larger effect on sperm count, and the researchers worry these influences will cause even more damage with each passing generation.
"We've seen effects over the course of several decades," Hunt said. "What about several generations? Infertility is becoming more common. Are we creating the perfect storm?"
The findings were published in a recent edition of the journal PLOS Genetics.
