"It was migrating from the bottle into the water," Belcher explained.
This latest study tried to assess the effect from "normal" use, looking at both "old" polycarbonate water bottles from a local climbing gym as well as new bottles of the same brand.
The age of the bottle made no difference in the amount of BPA released.
However, if the bottles were briefly exposed to boiling water, they released BPA 55 times more rapidly than before being dunked in the hot water, the study said.
"There's nothing new in this paper," said Steven Hentges, executive director of the polycarbonate business unit of the American Plastics Council. "Migration has been studied many times before. In a sense, this is good news because it confirms what we already know."
Kirby Donnelly, department head of environmental and occupational health at the Texas A&M School of Rural Public Health, said the new finding was "not surprising" because it is a basic principle of chemistry that if a solvent is heated up, it will form a liquid solution.
"With BPA there are such contradictions as to whether it is toxic or nontoxic; a lot of times, it comes down to dose and duration," he added.
What does this mean to the average consumer?
According to Belcher, dishwashing temperatures might be OK but he stressed that even without the boiling water, such bottles do release small amounts of BPA.
For his part, Belcher avoids polycarbonate plastic. "That's been my personal choice," he said.
Visit Statistical Assessment Service for more on BPA.
SOURCES: Scott Belcher, Ph.D., associate professor, pharmacology, University of Cincinnati; Steven Hentges, Ph.D., executive director, polycarbonate business unit, American Plastics Council; Kirby
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