(CBS) Is your kid's brown-bagged school lunch unsafe?
A new study suggests sacked lunches are breeding grounds for bacteria that cause vomiting, diarrhea, or even death in some children.
"Sack lunches packed by parents can be an inexpensive alternative to school-prepared lunches - but they can also make kids sick" the authors said in a written statement.
What's the problem? High temperatures.
For the study - published in the September issue of Pediatrics - researchers checked temperatures of 705 sack lunches at Texas child care centers 90 minutes before lunch time. Even though nearly half of them contained one ice pack, only 1.6 percent of the lunches were kept at what researchers considered a "safe temperature zone."
"We thought it might be bad, but we did not know it was that bad," study author Fawaz Almansour, a nutritional studies researcher at the University of Texas at Austin Department of Nutritional Sciences, told ABC's "Good Morning America."
The study showed that more than 97 percent of meats, 99 percent of dairy items, and 99 percent of vegetables were stored at unsafe temperatures - only 22 out of the almost 1,400 food items were considered safe, Time reported.
What should parents do? The USDA's Food Safety and Inspection Service recommends that parents freeze some types of food, like mayonnaise-less sandwiches, the night before to keep them cool until lunch time. Lunch bags should be well-insulated and contain an ice pack or a frozen juice box to cool down the bag's contents.
Experts agreed the study has an important message although too-warm food is only one cause of foodborne illness in kids.
Dr. Harley Rotbart, a professor of pediatrics and microbiology at the University of and author of Germ Proof Your Kids, told GMA. "The much greater risks come from inadequate handwashing... and from home kitchen contamination of countertops, sinks and other inanimate objects with insufficiently cooked meat, chicken and fish."
Keep clicking to see ways parents can prevent.