Egg graders with the U.S. Department of Agriculture were present at two Iowa egg processors at least 40 hours a week before they were involved in a national salmonella outbreak, USA Today reports.

The staff charged with inspecting the size and quality of eggs at Wright County Egg and Hillandale Farms were also supposed to check for rodents and other disease-spreading vermin, the newspaper reports. But the USDA says its egg graders only look for vermin in the processing buildings where they're based.

The Senate is expected to take up food safety legislation this fall that would increase the Food and Drug Administration's authority. Rep. Rosa DeLauro (D-Conn.), chair of the House Appropriations Agriculture subcommittee, has asked the USDA for more information about what its egg graders knew of conditions at the plant.

"It has never been more clear that we need to pass strong FDA food safety legislation this year," said DeLauro. "In the long term, a single food agency is needed that focuses exclusively on protecting our food supply."

"USDA has been working to close gaps and improve the safety of the meat, poultry and processed egg products over which we have authority and the FDA is taking action to address the fact that they have not had all of the tools needed to prevent outbreaks in areas where they have authority, such as shell eggs," Agriculture Secretary Tom Vilsack told USA Today.