Improperly stored lunch food can potentially make kids sick, according to a study published in the journal Pediatrics.

Texas researchers visited nine preschool child-care centers and tested 1,361 perishable food items. Only 22 of those foods were considered to be at safe temperatures. Virtually all of the perishable foods- meat, dairy products, and vegetables- were being stored at unsafe temperatures, researchers found.

"Sack lunches packed by parents can be an inexpensive alternative to school-prepared lunches, but they can also make kids sick if not kept at a safe temperature," the group said in a press release.

The researchers defined "unsafe" as anything that sat for more than two hours between 39 and 140 degrees Fahrenheit, according to MSNBC.  

Using ice packs does not seem to help, either.

"Study authors suggest that parents and the public need to be educated on safe food packing practices in order to prevent bacteria from growing and potentially causing illness," the researchers said in the press release.

According to the study, kids are more prone to bacterial infections than adults.

"It is more of a scary situation for children than for adults," Fawaz Almansour, the lead author of the paper and a researcher at the University of Texas at Austin, told Time magazine. "Kids' immune systems have not adapted to these diseases."

Still, not all doctors are too concerned about the findings.

"The risk from improperly refrigerated sack lunches is real, but relatively minor in the overall picture of foodborne illnesses," Harley Rotbart, a pediatric infectious diseases expert at the University of Colorado's medical school, told ABC News.

"The much greater risks come from inadequate handwashing -- by food preparers and food consumers -- and from home kitchen contamination of countertops, sinks and other inanimate objects with insufficiently cooked meat, chicken and fish," he said.