(USA TODAY) -- Even when parents and caregivers are aware of infants' food allergies and have been instructed in avoiding potentially dangerous trigger foods, allergic reactions still occur, the result of both accidental and non-accidental exposures, a study finds.

Accidental exposures from unintentional ingestion, label-reading errors and cross-contamination resulted in 87% of 834 allergic reactions to milk, eggs or peanuts in the study, reported in today's Pediatrics.

Non-accidental exposures resulted in 13% of reactions. It's not clear why caregivers would purposely give a child a known allergen, maybe "to see if (the child) has outgrown an allergy, or how allergic he is," says lead author David Fleischer, a pediatric allergist at National Jewish Health in Denver.

Fleischer and colleagues analyzed data from 512 infants, ages 3 months to 15 months, diagnosed with or at risk for having an allergy to milk, eggs or peanuts. In a 36-month period, 72% had at least one reaction; 53% had more than one.

"This is a high rate of reactions and concerning," says Fleischer, noting that parents were counseled "on a regular basis about food avoidance."

Only 50% of the accidental reactions were from food provided by parents, highlighting the importance of educating all caregivers -- grandparents, siblings, babysitters and teachers -- about food allergies, he says.

"There is still some misunderstanding in the general public about food allergy and how serious it can be," says Ruchi Gupta, an associate professor of pediatrics at Northwestern University. She led a study published last year that found 8% of U.S. children younger than 18 have a food allergy. About 40% had experienced a life-threatening reaction, such as blocked airways or a drop in blood pressure.

Concerns that skin contact or inhalation might trigger severe reactions were not supported by the new study, Fleischer says. "The vast majority happened from ingestion."

Only 30% of severe allergic reactions were appropriately treated with an epinephrine injection, even when caregivers said they felt that was warranted. Epinephrine helps stop reactions by relaxing muscles in the airways and tightening blood vessels.

There's often a "fear of using epinephrine, a concern that there will be side effects," Fleischer says. "In studies that we've done, parents are surprised how quickly and effectively it works."

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