High levels of bisphenol A in paper currencies from several countries, and implications for dermal exposure.

The sources of human exposure to bisphenol A (BPA) are not well characterized. Little is known about the presence of BPA in paper products, especially in paper currencies, and its implications for human exposure. In this work, paper currencies from 21 countries (N = 156) were analyzed for BPA, which was measured in 19 mm punches taken from three spots on the paper currencies. BPA was found in all paper currencies at concentrations ranging from 0.001 to 82.7 μg/g (mean 4.94; median 1.02) and the concentrations in samples taken from the middle portion of the currencies were higher than those taken from peripheral portions. We also examined the transfer of BPA from thermal receipt paper to currencies by placing currencies in contact with thermal receipt papers for 24 h in a wallet. Concentrations of BPA dramatically increased after 24 h of contact with thermal receipt papers, suggesting that thermal receipt paper is an important source of BPA in paper currencies. The estimated daily intake of BPA through dermal absorption from handling paper currencies was on the order of a few nanograms per day.