BILLINGS - Americans consume 8-billion gallons of bottled water a year. Makes one wonder why we are turning our backs to tap water, and if there is a risk in doing so.

There is no proven danger, but certain plastics used for all sorts of containers give off trace amounts of a chemical called Bisphenol A, or BPA. Carl Castles, assistant professor of biology at MSU-Billings, said the chemical can mimic the female hormone Estrogen.

"So, that's the concern is that we're taking estrogenic compounds into our bodies when we drink water from these types of bottles, or anything from these types of plastics," said Castles.

High-dose experiments in animals show a risk of infertility and cancer, but Castles said this is not necessarily relative to humans. "The Bisphenol A that you take into your body via water is actually changed chemically into an inactive form for the most part when it's in your body," said Castles. "Your liver does the job for you and a lot of the animals in the studies, like rats, don't do that as well."

Plastic containers with the number 3, 6 or 7 on the bottom of them have the potential to release the chemical.