From Science News:
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While working at Polaroid Corp. for more than a decade, John C. Warner learned about the chemistry behind some carbonless copy papers (now used for most credit card receipts) and the thermal imaging papers that are spit out by most modern cash registers. Both relied on bisphenol-A...
“When people talk about polycarbonate bottles, they talk about nanogram quantities of BPA [leaching out],” Warner observes. “The average cash register receipt that's out there and uses the BPA technology will have 60 to 100 milligrams of free BPA.” By free, he explains, it’s not bound into a polymer, like the BPA in polycarbonates. It’s just the individual molecules loose and ready for uptake.
As such, he argues, when it comes to BPA in the urban environment, “the biggest exposures, in my opinion, will be these cash register receipts.” Once on the fingers, BPA can be transferred to foods. And keep in mind, he adds, some hormones — like estrogen in certain birth-control formulations — are delivered through the skin by controlled-release patches. So, he argues, estrogen mimics like BPA might similarly enter the skin.