Despite the fancy lunch box and ice packs, your child's - or your - lunch may be prone to food-borne bacteria according to a study reported in "Pediatrics."

Brown Bag Lunches Prone to Overheating

By Crystal Phend, Senior Staff Writer, MedPage Today Published: August 08, 2011 Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco.

Action Points   Explain that nearly all lunches packed from home get too warm to prevent foodborne illness despite use of ice packs. Point out that even with multiple ice packs, more than 90% of perishables in the lunches reached unsafe temperatures. Nearly all lunches packed from home get too warm to prevent foodborne illness despite use of ice packs, according to a study of preschoolers' sack lunches. Only 1.6% of perishable food items found among more than 1,300 tested from lunch bags at Texas daycares remained at a safe temperature by mid-morning, Fawaz D. Almansour, of the University of Texas at Austin, and colleagues found. Even with multiple ice packs, more than 90% of perishables in the lunches reached unsafe temperatures, the group reported in the Sept. issue of Pediatrics. While the study didn't document whether any actual harm resulted, incidence is higher and complications of food-borne bacterial infection worse in younger children, Almansour and colleagues noted. The findings likely apply to older kids and adults who carry lunch to work as well, they suggested. A better understanding of how to pack lunch safely -- and perhaps development of ice packs and lunch bags that do a better job -- deserves attention, they added. About half of daycare centers in the U.S. require kids to bring lunch from home. The investigators examined lunches of 235 daycare attendees at nine Texas centers. The individual contents of their sack lunches assessed on three random days between 9:30 and 11 a.m. Of the 705 lunches, 11.8% were stored in a refrigerator, but teachers often left them sitting out for a couple hours first. The rest were stored at room temperature in cubbies without much air circulation. While about 91% of the lunches were sent in insulated plastic bags, the mean temperature of food items reached nearly room temperature (63.7 °F). Just 22 of the 1361 perishable food items (1.6%) were in the "safe" range below 39.2°F. Ice packs didn't help much. Only five of the 61 perishable food items with multiple ice packs in the lunch bag stayed the right temperature (8.2%). Refrigeration didn't appear effective either, as only four of the 458 items stored there (0.9%) were an acceptable temperature. The problem there may have been how long lunches stayed at room temperature before refrigeration or perhaps because the insulated bags kept out the cold, the researchers suggested. "These results indicate an urgent need for parents and child care personnel to be educated in safe food practices," they argued in the paper. Cold food left at a temperature over 39.2°F for more than two hours has to be tossed out because the heat-resistant toxins bacteria produce in that time can cause foodborne illness, the group noted. They pointed out that temperature measurements in the study were taken at least 1.5 hours before the children were supposed to eat their lunches. That may have led to conservative estimates of temperature when eaten, but measurements had to be taken then because kids could start eating snacks out of their lunch as early as one hour before lunchtime. Another limitation was that in an attempt to avoid cross-contamination, the researchers measured surface rather than core temperatures. The study was funded by the National Institutes of Health. The researchers reported having no conflicts of interest to disclose.

Primary source: Pediatrics Source reference: Almansour FD, et al "Temperature of foods sent by parents of preschool-aged children" Pediatrics 2011;128.