As concerns grow over the use of bisphenol A, or BPA, in consumer products ranging from water bottles to food cans, it's already being phased out of certain items.
But that doesn't mean the average American can get through a day without exposure to BPA, a chemical that could cause a range of health issues, including reproductive problems, cancer, diabetes, cardiovascular disease, obesity and behavioral issues. The 2003-04 National Health and Nutrition Examination Survey conducted by the U.S. Centers for Disease Control and Prevention found detectable levels of BPA in 93 percent of 2,517 urine samples from people 6 years and older.
The chemical is contained in polycarbonate plastics, making them tough and lightweight compared to glass. These include some food and drink packaging, compact discs, impact-resistant safety equipment and medical devices. BPA is also used in epoxy resins to coat metal products such as food cans, bottle tops and water supply pipes. According to the National Institute of Environmental Health, some dental sealants and composites may also add to BPA exposure.
BPA is often found in thermal paper receipts, as color developer in the paper coating. People often tuck receipts into pockets, wallets or purses alongside paper money, contaminating currency with the chemical, according to a study published in the journal Environmental Science & Technology in September. Kurunthachalam Kannan, a researcher with the Wadsworth Center at the New York State Department of Health and an author of the study, noted that 52 samples of paper currency from 21 countries all were tainted with BPA.
The highest concentration of 82.7 micrograms per gram was found in Brazil.
Receipts are often tossed in with recyclable paper, too, Mr. Kannan noted in a July study published in the same environmental journal.
"BPA gets into the paper recycling process, which contaminates many of the paper products," he said.
Mr. Kannan found that BPA was found in milligram-per-gram levels in thermal receipt paper but only in microgram-per-gram levels in recycled items such as toilet paper, paper towels, paper napkins and newspapers.Brief history of BPA
According to the Bisphenol A Global Industry Group, the first reported synthesis of BPA, from phenol and acetone, was from Thomas Zincke of the University of Marburg, Germany, in 1905. Although he reported key physical properties of BPA (such as its molecular composition, melting point, solubility in common solvents), he did not propose any application or use for BPA.
In 1953, Hermann Schnell of Bayer in Germany and Dan Fox of General Electric in the United States independently developed manufacturing processes for a new plastic material, polycarbonate, using BPA as the starting material. Polycarbonate plastic was found to have a unique combination of useful properties -- optical clarity, shatter-resistance and high heat-resistance -- which later made polycarbonate part of everyday life in a variety of products, the industry group says on the website www.bisphenol-a.org.
Commercial production began in 1957 in the United States and in 1958 in Europe. About this same time, epoxy resins were developed with the versatility to meet a wide range of industrial and consumer needs.
Its widespread use in manufacturing was noted in a U.S. Environmental Protection Agency action plan on bisphenol A, dated March 2010. Production volume of the chemical in the United States was estimated at 2.4 billion pounds in 2007, with an estimated value of almost $2 billion.
"The levels are lower than in thermal receipt papers," he said.
Although the levels of BPA are significantly less in recycled paper products, it's still a concern, Mr. Kannan said.
"The general population comes into contact with the paper products that we analyzed," he said. "Obviously there is a source of exposure that has not been studied before."
A Harvard School of Public Health study looked at another potential source of daily exposure for Americans -- canned food.
The study linked consuming canned soup to elevated BPA levels. Participants in one group were given one serving of canned vegetarian soup once a day for five days. The other group consumed one serving of vegetarian soup made from scratch for five days.
Participants were given only 12 ounces of soup, noted lead author Jenny Carwile, and some complained that it wasn't even enough food for lunch. After just five days, researchers checked the concentration of BPA in the participants' urine.
Urine samples from the participants that consumed the canned soup showed a 1,221 percent increase in BPA compared to those who consumed the fresh soup.
"It was very surprising because we gave them so little canned food," Ms. Carwile said. "It was a very moderate amount of canned food."
She noted that manufacturers are starting to phase BPA out of plastic baby bottles, water bottles and other items, but we're a long way from being BPA free, and limiting the consumption of canned food is one way to reduce exposure.
"A lot of people try to be aware of their exposure to chemicals like BPA, and this is one more way that they can avoid this chemical if they want to," she said.
"It's not about canned soup in particular," she said. "It's about canned food."
A long-term study published last month in the journal Pediatrics looked at exposure to BPA in the womb and how it can affect children's behavior.
Studies in animals indicated that exposure to BPA could cause behavioral problems, noted Joe Braun, Harvard Public Health researcher and the study's lead author.
The study followed a group of women from the second trimester of pregnancy up until the child's eighth or ninth birthday. During their pregnancies, the women were surveyed twice for demographic information and concentrations of BPA in their blood and urine were measured. Then, every year, the children would meet with researchers once a year for behavioral tests and give blood and urine samples. The children's behavior was measured using scales reported by the mothers. They reported issues like having trouble sitting still, having to be redirected often, or talking about being sad or depressed, Mr. Braun said, noting that it's a "valuable, reliable scale" that provides a continuous measure of behavior.
The researchers found each 10-fold increase in the mother's urinary BPA concentration during pregnancy was associated with about a 10-point increase on the scale measuring behavioral difficulties, but only in girls.
Boys, for reasons unknown to the researchers, showed less hyperactive behavior, Mr. Braun said.
Studies in animals have shown, though not consistently, that BPA may affect behaviors differently in males and females because BPA acts like a hormone, and hormones are important for brain development, Mr. Braun said.
The National Resources Defense Council filed a petition with the U.S. Food and Drug Administration in February 2008 requesting a ban on BPA in any packaging that would come in contact with food. When the agency did not respond, NRDC filed a suit asking the court to intervene and require the FDA to respond.
In a Dec. 7 settlement with the NRDC, the FDA committed to decide by March 31 whether BPA should be banned from use in food and drink packaging.
In the meantime, how can the average consumer avoid coming into contact with BPA?
Mr. Kannan says people who work as cashiers and come into contact with thermal receipt paper throughout the day should wear gloves.
"The perfect solution would be to stop using BPA in receipt papers," he said. "In the absence of that, if you have to have BPA on this paper, I would suggest washing your hands."
Ridding your home of plastics containing BPA might be easier than avoiding receipts. To determine if a plastic container contains BPA, look at the bottom of the container. A "7" in the recycling symbol means it might contain BPA. If it says "PC" below the recycling symbol, it definitely contains BPA, Ms. Carwile said.
Mr. Braun and Ms. Carwile recommended taking reasonable steps to avoid canned goods.
"If women are concerned about BPA, they can certainly take steps to reduce exposure," Mr. Braun said. But he noted that eliminating canned goods isn't practical for a lot of people.
"I certainly wouldn't want people to switch canned vegetables ... for cheeseburgers," he said.
Annie Siebert: firstname.lastname@example.org or 412-263-1613.
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