Remember not so long ago, when everyone was getting rid of their plastic water bottles and replacing them with metal ones? That's because they contained bisphenol A (BPA), a chemical used in the production of polycarbonate plastic. Several recent studies had linked BPA to a number of health problems, including breast cancer, heart disease, diabetes, and behavioral difficulties. The chemical was also found to be present in baby bottles and tin can linings, but a more recent study has exposed a source of BPA exposure that many people might not expect - thermal cash register receipts.

The research was conducted by Chunyang Liao and Kurunthachalam Kannan, of the New York State Department of Health and the State University of New York at Albany's School of Public Health.

Their study entailed analyzing hundreds of thermal cash register receipts, along with 14 other types of paper products, collected in the U.S., Japan, Korea and Vietnam. BPA was found in 94 percent of the receipts, in which it was used as a developer for the printing dye. The chemical was not present in receipts from Japan, however, as that country stopped using BPA in receipts in 2001.

While the concentration of BPA was highest in receipts, lower levels of it were also found in 81 percent of the other paper products. This, the researchers stated, was due to the recycling of receipts, which resulted in their BPA content being passed on to items such as napkins, toilet paper and food packaging.

Altogether, it was concluded that the handling of thermal cash register receipts was the source of over 98 percent of consumer exposure to BPA from paper. That paper-based exposure, in turn, was estimated to account for up to two percent of the general population's total daily BPA exposure. For people working around thermal receipts, however, the percentage could be considerably higher.

A paper on the study was recently published in the journal Environmental Science & Technology.