Comparing how well assorted cleaners or plain water remove Ara h 1, the most common peanut allergen, the Hopkins researchers showed that most products performed well, although dishwashing liquid left tiny traces of Ara h 1 on some cafeteria tables, and alcohol-based hand sanitizer left residual allergen on half of the hands tested.
"It's possible that dish soap creates a film over eating surfaces, making it difficult to clean underneath," says Children's Center pediatric allergist Robert A. Wood, M.D., senior author of the study. "But our results suggest that even if a child licked the table vigorously after it had been cleaned with dish soap, he probably still couldn't get enough allergen to cause a reaction."
Wood says the bigger concern to emerge from the study was the failure of hand sanitizers, frequently seen by teachers as more convenient than sending children to the bathroom to wash up, to eliminate Ara h 1. "Their use may not really remove the allergen, but just spread it around," he says.
In the study, published in the May issue of the Journal of Allergy and Clinical Immunology, researchers applied a teaspoon of peanut butter to the hands of 19 peanut allergy-free adult volunteers. Participants then washed their hands with various cleaning agents, plain water and an antibacterial hand sanitizer. Hand wipes, liquid soap and bar soap all removed the peanut allergen. Water left residual Ara h 1 on 3 of 12 hands, and hand sanitizer left residual allergen on 6 of 12 hands.
Researchers also compared the performance of plain water, dishwashing liquid, Formula 409 cleaner, Lysol sanitizing wipes and Target brand cleaner with bleach in removing a teaspoon of peanut butter from a clean table. All cleaning techniques except dishwashing soap removed the allergen; dish soap left residual Ara h 1 on 4 of 12 samples.
The Hopkins researchers sampled various surfaces in six schools and preschools in the Baltimore area, and found traces of allergen on only 1 of 13 water fountains, and on none of 22 desks or 36 cafeteria tables.
In an effort to simulate and measure potential airborne allergen exposure at schools and sporting events, and on airplanes, the investigators asked the 19 volunteers to eat peanut butter sandwiches, roasted whole peanuts in their shells and shelled peanuts while wearing small air monitors to study the amount of inhaled allergen. They also were asked to discard peanut shells on the floor and walk on them, and open 15 bags of unshelled peanuts and eat them.
The investigators failed to detect Ara h 1 in any of these settings, though Wood cautions that the team's measuring techniques might not have been sensitive enough to find small amounts of allergen. "Future studies that include challenging patients with peanut allergy in these settings will be needed to more reliably assess the risks of airborne exposures," he says.
Peanut allergy is the third most common food allergy in young children and the most common food allergy in older children, adolescents and adults.
The study was funded by the Myra Reinhard Family Foundation. Coauthors were Tamara T. Perry, M.D., and Mary Kay Conover-Walker of Johns Hopkins Children's Center, and Anna Pomés, Ph.D., and Martin D. Chapman, Ph.D., of INDOOR Biotechnologies, Charlottesville, Va.
Perry, Tamara T. et al, "Distribution of Peanut Allergen in the Environment," Journal of Allergy and Clinical Immunology, May 2004, Vol. 113, No. 5.
Johns Hopkins Children's Center
Division of Pediatric Immunology & Allergy