Five hours and a dose of steroids later, Isabelle recovered, but the memory still haunts the now-8-year-old girl.
"It was a pretty traumatic event for her," Toni Thomelin said. "She was eating something she thought was safe, something she'd eaten before. It never dawned on us that something could be completely mispackaged."
In fact, many foods that U.S. consumers routinely buy have the potential to be mispackaged—and dangerous, food safety experts say. The most common food recalls in the U.S. aren't for salmonella, listeria or other pathogens. Instead, they're for eight undeclared allergens—milk, egg, peanuts, soy, fish, crustacean shellfish, wheat and tree nuts—that accidentally get into foods because of manufacturing errors.
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No one keeps tabs on how many injuries or deaths have been caused by undeclared allergens, but Food and Drug Administration researchers found dozens of reactions associated with recalls reported from 2005 to 2010—and 10 percent to 15 percent of such reactions are severe and can lead to death if untreated.
There have been nearly 70 such recalls so far this year, including an announcement last week that Ocean Spray, the top maker of dried cranberries, is recalling two production lots of its Greek Yogurt Covered Craisins because the snacks may contain peanuts instead.
"This is one of our worst nightmares!" Toni Thomelin said. "Covered with yogurt, never would we expect the inside to be a peanut."
For the up to 15 million people across the country who suffer from food allergies, such mistakes can be life-threatening, said John L. Lehr, chief executive of the advocacy group Food Allergy Research and Education, or FARE.
"Undeclared allergens are definitely a source of concern because they can have serious consequences," he said. "Every three minutes, someone is being taken to the emergency room for a food allergy reaction."
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And such recalls are growing, government researchers say. Between 2005 and 2010, there were 1,637 food recalls in the U.S., including 520 for undeclared allergens, or 31 percent. When FDA officials checked again last year, using the agency's Reportable Food Registry database, undeclared allergens accounted for 44 percent of the recalls.
And those are the equivalent of Class I recalls, the most dangerous type, where there is a likelihood of serious adverse events for allergic consumers. In the 2005 to 2010 study, 64 of the allergen recalls resulted in reactions that affected 96 people.
Ten percent to 15 percent of such allergic reactions are severe or result in anaphylaxis, a severe, full-body reaction that can lead to death within minutes if left untreated. "Alarmingly, two-thirds or more of these cases involved children," FDA researchers wrote.
And those are only the reported reactions. There's no universal monitoring system for allergic reactions in the U.S. and emergency department reports often fail to say whether such problems are caused by food, said Steven Gendel, the FDA's food allergen coordinator.
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Consumers often think of peanuts as the top allergen, perhaps because of growing discussion about topics like peanut-free lunch tables and allergy bullying in schools—and because the number of allergic kids in the U.S. jumped by 50 percent between 1997 and 2011, according to the Centers for Disease Control and Prevention.
But milk is actually the chief cause of reactions from undeclared allergens, FDA researchers say. Milk can make its way into many foods in many forms, with disastrous results.
"A trace amount of milk can lead to a very serious reaction," Lehr said.
The only way to prevent allergic reactions is to avoid them entirely, said Dr. Stephen A. Tilles, an asthma and allergy specialist in Seattle. And the only way to treat them is with a dose of epinephrine—a so-called EpiPen—which counteracts the allergen quickly. Undeclared allergens pose a far smaller problem than outright mistakes—eating foods made with known triggers. Still, they're dangerous, Tilles said.
"Especially in these families that have done a good job of avoiding allergens, it's easy to be caught off guard," he said, noting that he advises families to have an allergy emergency plan in place, including practicing using the EpiPen.