Schoolchildren around the U.S. are eating meat that falls short of the safety standards of many fast food restaurants, the USA Today reported Wednesday.

The U.S. Department of Agriculture maintains the meat it buys for the National School Lunch Program "meets or exceeds standards in commercial products."

But the paper’s investigation revealed fast food chains including McDonald’s, Burger King, Jack in the Box and KFC have much more stringent quality requirements for the food they serve, with some of them testing meat for dangerous pathogens up to 10 times more a day than the USDA.

USDA-purchased meat ends up on the plates of 31 million students a day, worrying some that children’s still-developing immune systems are more susceptible to potentially deadly bacteria like salmonella and E. coli.

The USDA’s standards for meat sent to schools exceed minimum standards for meat sold at supermarkets, but fast food restaurants have raised the bar when it comes to quality control, the report notes.

While the government has a zero tolerance policy for meat that tests positive for salmonella or E. coli O157:H7, fast food chains’ more stringent standards also test for "indicator" pathogens that could indicate more dangerous bacteria is present in the meat.

Government officials are looking at beefing up safeguards for school food. Congress will reexamine the Child Nutrition Act, which governs the lunch program, next year. And in light of the USA Today investigation, Agriculture Secretary Tom Vilsack has pledged to launch an independent review of testing standards of ground beef sent to schools.