Students may be getting a less-than-nutritious extra ingredient in the lunches and breakfasts they eat in their school cafeterias, a new study suggests. Whether it's enough to worry about, though, is a matter of dispute.
Researchers at Stanford University and the Johns Hopkins University's Bloomberg School of Public Health say school-prepared meals may contain unsafe levels of bisphenol A, or BPA. Often found in canned foods and plastic packaging, the widely used chemical can mimic human hormones. Research has shown it can harm the developing brains and bodies of fetuses, infants and children.
"There are known sources of BPA being used in school food," said Jennifer C. Hartle, a postdoctoral research fellow at Stanford and lead author of the study, which was recently published in the Journal of Exposure Science and Environmental Epidemiology.
She suggested parents should press their school systems to see that their children are fed fresh rather than canned or prepackaged fruits and vegetables.
"Everybody knows about pesticides as a potential problem with food," she said. "Well, the packaging is something else to consider."
But the head of the Maryland-based School Nutrition Association and a spokesman for the chemical industry countered that the study really gives parents no cause to worry about how much BPA their children may be getting in school lunches and breakfasts. The levels calculated in the study are all below established safety limits, they said.
Hartle, a former fellow at Hopkins' Center for a Livable Future, acknowledged that under this study, the most BPA a student might get from a single meal was far below the threshold set by the federal government. But that standard was set by the Environmental Protection Agency in 1988, the study noted, and more than 100 studies since have found health effects in animals from much lower doses of BPA.
Along with her Hopkins co-authors, Hartle interviewed food service managers and visited school kitchens and cafeterias to find out what foods are served and how they're kept. Relying on studies finding BPA leaching into food from cans and plastic packaging, they calculated how much students might be ingesting in a single meal.
While plastic packaging of all types and even plastic eating utensils may contain BPA, Hartle said canned foods are the chief source. Government nutrition standards and health advocates have pushed schools to stop serving as much pizza, she said, but that isn't necessarily cutting out the BPA.
While many schools now serve apples, oranges and bananas, canned foods remain a staple, Hartle explained. In her tour of school cafeterias, she said, she noticed that salad bars installed in response to calls for more nutritious school lunches often contain canned and prepackaged fruits, beans and other items.
Depending on what's served and what actually gets consumed — the researchers estimated 12 percent gets tossed uneaten — students could be getting anywhere from a negligible amount of BPA up to 1.19 micrograms per kilogram of body weight, the study concluded.
The EPA safe-intake limit is 50 micrograms per kilo of body weight. But this year, reacting to recent research, the European food safety authority lowered its limit to 4 micrograms per kilo.
The new study comes amid renewed scientific concerns and debate about the health effects of all endocrine-disrupting chemicals, including BPA. While poisonous substances generally do less harm as the dose gets lower, researchers have found chemicals that disrupt hormones can cause trouble at very low concentrations.
The Endocrine Society, a group of scientists who study hormones, recently reported that 1,300 studies published in the last several years have strengthened evidence tying low doses of endocrine-disrupting chemicals to reproductive and neurological problems and some cancers. Studies also have linked exposures in the womb or in infancy to increased risks of diabetes and obesity later in life, the group said. It called for more research, but also urged the public and policymakers to increase efforts to keep such chemicals out of food, water and the air.
Andrea Gore, a pharmacology professor at the University of Texas at Austin and lead author of the society's statement, said the BPA levels estimated in school meals may not seem high enough to worry about, but shouldn't be considered in isolation.
"This lunch is only part of the exposures a child will get during the day," she said. They could also be getting BPA, she added, in "what they eat for dinner, what they eat for snacks, what they're exposed to beyond just the food."
Gore also noted that the BPA in school meals may affect poor youngsters more, as their lunches and breakfasts are provided free or at reduced cost.
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Patricia Montague, CEO of the School Nutrition Association, based in National Harbor, defended the safety of school meals and pointed out the study didn't conclude that BPA exposure is any greater in cafeteria lunches than from meals eaten at home or elsewhere. She also insisted schools have reduced use of canned foods and rely more on fresh and frozen produce.
Some scientists maintain the research to date hasn't really established that minute doses of endocrine-disrupting chemicals can cause problems. The American Chemistry Council, an industry group, criticized the Endocrine Society's report, saying it makes "broad, unsupported claims."
As for the school meal study, council spokesman Steven Hentges said it ought to reassure rather than worry parents. While acknowledging that the EPA limit is no longer a valid safety gauge, he said the BPA consumption estimates in the study were below the much lower European limit.
Hartle acknowledged that the issue is complex, and that shunning the school cafeteria won't necessarily protect children from exposure to BPA. Personally, she said, she sends her two children, ages 7 and 10, to school with metal lunchboxes and thermoses and sees that they eat fresh fruits and vegetables and whole-grain breads.
"They're a reason to keep trying to find the answer," Hartle said.