More than 1.5 million dozen shell eggs distributed in six states have been voluntarily recalled because of possible salmonella contamination, federal regulators announced Wednesday.

The U.S. Food and Drug Administration said Midwest Poultry Services initiated the recall, which covers 1,589,577 dozen cartons of white shell eggs and brown cage-free shell eggs.

According to the FDA, the recalled eggs were sold under multiple brand names, including Kroger, Brookshire's, Country Morning, Simple Truth and Sunups. The recall also includes various bulk Grade A and Grade AA eggs.

The products were distributed to retail and food service customers in Texas, Oklahoma, Arkansas, Louisiana, New Mexico and Mississippi, as well as to other smaller retail outlets, the FDA said.

The affected eggs were produced at two farms in Texas, according to the agency. Regulators said the potential issue was identified through routine environmental testing. Such testing is a core requirement of the FDA's Egg Safety Rule, which took effect in 2010 and mandates prevention measures at facilities with more than 50,000 laying hens. No illnesses have been reported in connection with the recalled eggs.

Salmonella Enteritidis is among the most common salmonella serotypes tied to shell eggs, and the Centers for Disease Control and Prevention estimates that salmonella causes approximately 1.35 million infections in the United States each year across all food sources.

"When we learned of a possible issue with egg safety, we began diverting eggs to a breaking plant where they would be pasteurized to kill any foodborne pathogens," Midwest Poultry Services told FOX Business in a statement on Thursday. Pasteurization involves heating eggs to temperatures sufficient to kill salmonella bacteria.

"We also began a robust internal investigation and initiated testing protocols to identify potential sources of SE," the company added, referring to Salmonella Enteritidis.

"Producing safe, quality food for those who eat our eggs is our highest priority, and this voluntary investigation and recall demonstrates that commitment."

The recall covers several carton sizes and egg counts. Consumers can identify affected products by the codes printed on the side of the carton.

The eggs were packed and distributed between June 6 and July 3, with sell-by or best-by dates ranging from July 20 through Aug. 17. The affected cartons also carry plant code P-1950 or 840962 and a Julian Date between 157 and 184.

Consumers who bought the recalled eggs should not eat them and should return them to the place of purchase for a full refund.

The FDA said salmonella can cause serious and sometimes fatal infections in young children, older adults, frail people and individuals with weakened immune systems.

Healthy people infected with salmonella may experience fever, diarrhea that may be bloody, nausea, vomiting and abdominal pain. In rare and severe cases, the bacteria can enter the bloodstream and cause more serious illnesses, including arterial infections, infected aneurysms, endocarditis and arthritis.

Consumers with questions can contact Midwest Poultry Services' consumer helpline at 574-405-9531, available Monday through Friday from 8 a.m. to 4:30 p.m. EST, or email recallassistance@mpseggs.com.