Washington, Aug 11 (IANS): Currency notes may be contaminated with the toxic substance bisphenol A (BPA), known to cause male infertility.

Kurunthachalam Kannan and Chunyang Liao from the Wadsworth Centre, New York State Department of Health, and State University of New York, respectively, found BPA after examining currency notes from 21 different countries.

Studies suggest that BPA acts as an endocrine disruptor - meaning it mimics the action of the sex hormone estrogen. Exposure to the toxic substance has been linked with a variety of health problems.

The highest BPA levels were found in currency notes from Brazil, the Czech Republic and Australia, while the lowest occurred in paper money from the Philippines, Thailand, and Vietnam. Levels in US notes were about average, according to a Wadsworth statement.

Kannan and Liao also found that the most likely source of the BPA in the currency is the thermal paper used in cash register receipts. They showed that receipts can transfer BPA on to cash when placed next to it or when a receipt is touched before handling currency.

Manufacturers use BPA to make polycarbonate plastics used in some consumer products, including water bottles, sports equipment and household electronics, say Kannan and Liao.

Although a recent study found traces of BPA in US currency, nobody knew until now about BPA in paper money worldwide.

The report notes, however, that "estimated daily intake from paper currencies were 10-fold lower than those reported from exposures due to [indoor] dust ingestion in the United States".