Concerns about the health effects of bisphenol A have led manufacturers to produce and market BPA-free products. However, a new study has found that one of the compounds that replaces BPA is just as prevalent in paper products and could lead to significant human exposure. Because of these results, the scientists who performed the study say that toxicology research is desperately needed on the BPA alternative. Manufacturers use BPA to make plastics, and paper companies apply it to heat-sensitive sales receipts to help develop ink. However, about 300 animal studies have shown that BPA has a wide range of effects as an endocrine disrupter, says Frederick vom Saal, a developmental endocrinologist at the University of Missouri, Columbia, who was not involved in the new study. Endocrine disrupters act like natural hormones and can interfere with cellular pathways. Animal studies have found that BPA can cause health problems, such as obesity and mammary and prostate tumour growth, vom Saal says. More than 30 epidemiological studies have linked exposure to BPA to similar effects in people, he adds. People readily absorb BPA through the skin and into the bloodstream after it sloughs off of thermal receipts, says Kurunthachalam Kannan, an environmental chemist at the New York State Department of Health and a co-author of the study, published in the journal Environmental Science & Technology. He and his team were tracking BPA concentrations on thermal receipts in 2010 when they noticed that paper companies were replacing BPA with bisphenol S (BPS), which is structurally similar to BPA and also has oestrogen-like activity, Kannan says. To look at BPS in thermal paper, the scientists collected thermal receipts from stores in the U.S., Japan, South Korea, and Vietnam. They extracted BPS from each receipt and confirmed the compounds identity using high-performance liquid chromatography with tandem mass spectrometry. They found an average concentration of 0.181 mg of BPS per gram of paper, with some samples reaching 22 mg/g. Kannan and a colleague previously reported similar concentrations for BPA. The researchers then used a mathematical model to estimate a persons daily intake of BPS. The model assumed the rate of transfer of BPS to skin was similar to that of BPA and took into account how often and how long people handled BPS-containing paper. The general population likely absorbs 291 ng of BPS per day through their skin, they concluded, while workers such as store clerks may absorb 21,804 ng/day. In a just-published paper, Kannans team report exposure data based on urine samples. The new study is important because it demonstrates that people may experience significant exposure to BPS, vom Saal says. Therefore, he adds, more information on BPS is needed. The fact that manufacturers replaced a known endocrine disrupter with a compound with similar oestrogen-like activity, he says, highlights the need to update the regulatory requirements for screening compounds for endocrine-disrupting activity.
Chemical & Engineering News, 23 May 2012 ;http://pubs.acs.org/cen/news ;