A University of Rochester Medical Center analysis of data published online Jan. 28 suggests that the controversial chemical bisphenol A could be lingering longer in the human body than previously thought, and could be getting into the bloodstream through sources other than food.
The scientists suggest that other sources for BPA in the bloodstream could include plastic pipe and dust from carbonless paper, such as cash register receipts.
``It is a very provocative study,'' said Sarah Janssen, senior scientist in San Francisco for the Natural Resources Defense Council, in a phone interview. ``The implications depend on the final conclusions, but if BPA is residing longer in bodies, there is the potential for greater toxicity; and if it is coming from places other than food, we have a lot of work to do to figure out where it is coming from.''
The American Chemistry Council of Arlington, Va., did not return phone calls inquiring about the study. But in an article posted on its Web site, Steve Hengtes, executive director of the ACC's Polycarbonate/BPA Global Group, called the conclusions of the study ``speculative at best,'' and said the levels of BPA found in the study are not a health concern.
Only one country, Canada, has taken action with regard to BPA. Health Canada in October said it will draft regulations to ban the import and sale of baby bottles containing BPA, even though its view is that BPA migration is too low to cause harm.
Some laboratory studies on rats have linked BPA to birth defects, low birth weights, cancer, early puberty and other health problems; so, it is likely the new study will add fuel to the growing controversy over the safety of BPA, and the steadfast insistence of the Food and Drug Administration that there is no current need to regulate the chemical in food containers.
That's a stance FDA reiterated in December, even after pressure from Congress last summer and stinging criticism last fall from a subcommittee of its own Science Board. FDA said it did not have enough data to propose a regulatory ban, and instead would further study the cumulative exposure a person faces from a variety of items that contain BPA, including food and beverage containers, coatings on gel tablets and plastic medical devices like tubing.
The analysis by the three scientists looked at 2003-04 data from the National Health and Nutrition Examination Survey conducted by the Centers for Disease Control and Prevention to see whether BPA levels fell with fasting, since previous studies have suggested that the primary exposure to BPA is through food.
The researchers looked at urine samples of 1,469 adults and compared levels of BPA based on how long the subjects had fasted. It was published online in the journal Environmental Health Perspectives.
``BPA levels did not decline rapidly with fasting time in this sample,'' said the study's lead author, Dr. Richard Stahlhut, a postdoctoral fellow in the Environmental Health Sciences Center of Rochester University's Medical Center in Rochester, N.Y.
``Things we thought we knew aren't necessarily so,'' he said, noting that previous studies indicated BPA completely metabolized within 24 hours and levels typically dropped in half in four to six hours. Their analysis, said Stahlhut, found that BPA levels dropped, but after eight hours leveled off and did not disappear.
``The persistence of BPA levels despite extended fasting appears to contradict'' previous risk assessments, most of which have been based on the premise that food is the main, if not exclusive, source of BPA and that rapid and complete BPA elimination occurs after exposure.
In addition, Stahlhut said the analysis suggests ``substantial nonfood exposure, accumulation [of BPA] in body tissues such as fat, or both. BPA accumulation in fat, if common, could have important health implications.''
The report cautioned, however, that more research needs to be done because of the limitations of the study, including use of self-reported fasting time, the exclusion of data from both children and adults, and questions related to BPA contamination or measurement error.
``We need a controlled study in a more controlled environment,'' agreed NRDC's Janssen. She said the study should look at whether people eat food from plastic containers warmed in a microwave, canned foods, canned beverages or drink liquids from polycarbonate bottles.
``The study also raises more questions about potential sources of BPA exposure, including whether it is coming from indoor air contaminants or even cash register receipts,'' she said.
While there are alternatives to PC bottles, Janssen expressed concern about numerous steel food cans having liners made from BPA, particularly tomato-based products and pastas, because she said there is no alternative to BPA-lined cans for those products.
``People don't know what substances their food cans are lined with,'' she said.
According to the North American Metal Packaging Alliance, BPA is a component in the interior epoxy coating for more than 90 percent of the food cans in the U.S.
Organic foods maker Eden Foods Inc. of Clinton, Mich., sells its line of bean products in BPA-free cans made by Ball Corp. The cans are lined with an oleoresinous enamel, made with resin from pine or balsam fir.
FDA has yet to respond to an October petition from NRDC to ban the use of BPA in food packaging. In addition, the attorneys general of New Jersey, Connecticut and Delaware sent letters in October to 11 manufacturers of baby products, asking them to stop using BPA in their baby bottles and other infant products.
In April, Wal-Mart Stores Inc. stopped selling baby bottles, sippy cups, pacifiers, food containers and water bottles containing BPA, in Canada. Both Wal-Mart and Toys R Us have said they will stop selling baby bottles that contain BPA in the U.S. sometime this year.
Energizer Holdings Inc.'s Playtex Infant Care unit and Thermo Fisher Scientific Inc., the maker of Nalgene sports bottles, have stopped using BPA in their new products.