(NaturalNews) Drinking water from plastic bottles made with the toxic chemical bisphenol A (BPA) increases urinary levels of the chemical by nearly 70 percent, according to a study conducted by researchers from Harvard University and the Centers for Disease Control and Prevention.

BPA, an industrial chemical that makes plastics hard and transparent, is widely used in plastic drinking bottles, infant bottles and other consumer products, and also in resins that line cans of food and infant formula. The chemical has been shown to disrupt the hormonal system, potentially leading to reproductive defects as well as brain damage, cardiovascular disease, cancer, obesity and diabetes.

"These astonishing results should be a clarion call to lawmakers and public health officials that babies are being exposed to BPA, and at levels that could likely have an impact on their development," said Renee Sharp, of the Environmental Working Group. "The adults in this study were willing participants who understood the risk of exposure, but babies are unwitting victims of the silent but serious threat this hormone-disrupting chemical poses to their health."

The study, conducted on 77 student volunteers, was published in the journal Environmental Health Perspectives.

A number of major retailers, including Toys R' Us, Wal-Mart, Nalgene, Gerber, Playtex and others, have agreed to phase out the chemical in some countries. The Environmental Working Group has published a guide to BPA-free baby bottles and formulas, which can be found at www.ewg.org/babysafe.

The state of Minnesota has banned the use of BPA in food containers intended for children three and younger, as have Chicago and New York's Suffolk County. California and Connecticut are also considering banning the substance.

"If the legislation to protect California's youngest from further exposure to BPA is defeated, those elected officials responsible for its demise should be held to account for protecting the profits of the chemical industry instead of children's health," Sharp said.

Sources for this story include: www.ewg.org.