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Jan. 30, 2008 -- Pouring boiling liquid into reusable water bottles or baby bottles made of polycarbonate plastic causes a much faster release of the estrogen-mimicking chemical bisphenol A, new research shows.
University of Cincinnati researchers reported that exposure to boiling water caused polycarbonate drinking bottles to release bisphenol A (BPA) up to 55 times more rapidly than exposure to cool or temperate water.
The jury is still out on whether BPA exposure poses a health risk to humans, even though the question was the subject of two expert panel reviews in the U.S. last year.
More than 6 billion pounds of bisphenol A are produced and used each year in the manufacture of the resins used to line food cans and in polycarbonate products. Almost everyone has measurable amounts of the man-made chemical in their blood, the CDC says.
It has long been known that BPA can cause genetic damage in lab animals, but it is not clear if the levels of leached BPA from polycarbonate bottles and other products are high enough to pose a threat to humans.
Scott M. Belcher, PhD, who led the study team, tells WebMD that while there is little direct evidence that BPA poses a risk to humans, many experts believe that it does.
"The consensus of the scientific community is that there is a clear reason to proceed cautiously," he says.
But Steven G. Hentges, PhD, who is executive director of the American Chemical Council's Polycarbonate/BPA Global Group, disagrees.
Hentges tells WebMD that the finding that BPA leaching accelerates at high liquid temperatures is nothing new, having been reported in numerous previous studies.
"The bisphenol A levels seen under heating conditions are still extraordinarily low and far below levels that have been determined to be safe by government bodies," he says.
The popularity of reusable, plastic polycarbonate drinking bottles has grown with rising concerns about the environmental impact of disposable plastic bottles.
Plastic water and soda bottles manufactured for one-time use are not made with polycarbonate plastic. But many baby bottles and those hard water bottles sold in outdoor and athletic stores are.