Adults in a study who drank most of their cold beverages from BPA-containing Nalgene polycarbonate bottles for a week experienced nearly a 70 percent increase in urinary levels of BPA, a synthetic estrogen found in plastic beverage bottles.

Results from the study, conducted by Harvard University and the U.S. Centers for Disease Control and Prevention, were published May 12 in the online journal Environmental Health Perspectives.

The data came from 77 Harvard student volunteers. Researchers sought to examine whether drinking cool or cold beverages from the commonly used polycarbonate containers increases BPA concentration in humans. The study compared urine levels of BPA after a “washout” period of one week (when subjects drank from stainless steel bottles) with levels after the test period of one week when volunteers had been drinking from the polycarbonate bottles.

The activist group Environmental Working Group is concerned about the results as they may apply to young children and infants, where the effect of BPA is unknown. The compound is considered an endocrine disrupter and a carcinogen by many.

Lawmakers are moving to ban BPA in products that could be used by small children, flanking the FDA which is permitting use of the controversial chemical. Nalgene, meanwhile, is coming up with BPA-free bottles.

BPA is also found in plastic water and beverage bottles, the ones that are so commonly used.

Be safe and drink from a stainless steel bottle! You can purify your water with a home water filter and carry it with you. Not only is it safer than bottled water, but it’s a lot less expensive.