Paper money from many countries contaminated with bisphenol A
MedWire News: Study results show that paper money from several countries across the world could be contaminated with the toxic substance bisphenol A (BPA).
An investigation revealed that this is likely to be due to contact with thermal receipt papers, as concentrations of the substance in paper money samples increased dramatically after being exposed to such receipts for 24 hours.
BPA, which is used in many industrial processes, binds to estrogen receptors and is a known endocrine disruptor. It may be a causative factor in cardiovascular disease, diabetes, metabolic diseases, and some cancers.
Exposure to BPA in plastics has been commonly reported, but less is known about its presence in paper products.
Chunyang Liao and Kurunthachalam Kannan, from the State University of New York at Albany in the USA, investigated whether and to what extent paper money from 21 countries was contaminated with BPA.
The basis for the study was that thermal papers containing BPA are still used as till receipts in shops from many countries due to their low cost, and that exposure to such papers could result in transfer of BPA to paper money.
The researchers found that all the currency bills sampled contained BPA in amounts ranging from 0.001 to 82.700 µg/g (mean=4.940 µg/g; median=1.020 µg/g).
The highest levels were sampled from Brazilian and Czech money and the lowest from money from Egypt, Thailand, Malaysia, and the Philippines.
The researchers tested their theory about transfer of BPA from thermal receipt papers by placing test bills in a wallet with BPA-containing receipt papers for 24 hours. After such exposure, the amount of BPA in the money had risen exponentially (100- to 1000-fold) and ranged from 6500 to 10,190 µg/g in each currency bill.
Of note, no links between the amount of BPA contamination and value, circulation time, or amount of ink used on the bills were observed.
Liao and Kannan estimated that the average daily dermal intake from handling paper currencies was likely to be at least a few nanograms per day.
Based on these results, they say that the highest estimated daily exposure would be 21.0 ng/day (0.35 ng/kg body weight per day) for Brazil. To put this in context, adverse endocrine effects from exposure to BPA have been reported at doses ranging from a few tens to a few hundreds of ng/kg body weight per day.
"Further studies are needed to assess exposure of cashiers and others who come into frequent contact with paper currencies," write the authors in the journal Environmental Science and Technology.
In addition, they suggest that "release of BPA from paper currencies into the air and subsequent inhalation exposures should be examined."
By Helen Albert