Dienstag, 26. Januar 2010
Bisphenol A BPA in receipts gets under your skin
Receipts and toilet paper on their way to be analyzed in the Kantonales Labor Zürich
Relatively high concentrations of BPA are in many receipts and other products made out of thermal paper. New tests by a renowned swiss laboratory, reported by swiss public radio DRS1, show that only few seconds of contact with thermal paper receipts are enough to put traces of BPA on human skin from where, as very preliminary results show, it penetrates into it. Through recycling, BPA finds its way into toiletpaper and consequently into the environment. producers of thermal paper say, BPA is harmless in skin contact according to tests following to OECD-guidelines 402-406 (see Koehler, page 15) and their products are ready for recycling. critical scientists and environmental organisations demand a ban of the substance.
BPA is the central building block for many kinds of plastics. polycarbonate baby-bottles are made out of polymerized BPA. aluminium-cans and tin cans on their inside are covered with a coating based on BPA. Unpolymerized, free BPA in relatively high concentrations is present in the active coating of thermal paper. There is an ongoing dispute on the safety or unsafety of BPA, while the scientific literature on effects in vitro and in vivo amounts to a long list of observations (excerpt).
For swiss public radio DRS the food quality control lab of the swiss canton of Zurich KLZH has measured that 1% up to 1,7% (17'000 mg/kg) of the weight of the thermal papers analyzed were pure BPA. These amounts were to be expected according to numbers provided by the industry. Tests of the same lab also show that after touching these thermal paper receipts with dry fingers for 5 seconds 0,5 to 2 micrograms of BPA were found on the skin. With wet or greasy skin the transfered amount rose up to 20 micrograms. Holding the paper for longer time, up to 60 seconds, did not raise the amount measured on the fingers any more. After applying a defined amount of BPA onto the fingers, then covering the area, after 90 minutes almost no BPA was found on the skin anymore. This lead the lab scientists to the conclusion that it must have been absorbed almost completely. But the KLZH wants to emphasize that these are just preliminary tests and that the evaluation of the dermal uptake of substances is outside of its field of competences. Earlier research by other authors had already indicated that dermal uptake of BPA is possible. An expert in pharmaceutical products for dermal application confirmed that the BPA molecule had almost "ideal" physico-chemical properties for skin penetration.
Through the recycling of thermal paper, BPA in measurable amounts (KLZH: 6 to 7 mg/kg) ends up in toilet paper, made out of recycled material. This way, BPA enters into the environment, as earlier work by Gehring et al has documented. scientific trials show, that the development of sensitive water-organisms can be heavily disturbed by minute concentrations of BPA. The swiss center for aquatic research EAWAG , who had found BPA in waste water, would like to see this leak of BPA into the environment closed. the swiss branch of the WWF demands a ban of BPA.
P.S. the idea for this research is owed to Janet Raloffs article "concerned about BPA? check your receipts!"