Two of the biggest U.S. meat processors on Tuesday defended a packaging technique designed to keep meat looking fresh at grocery stores even as U.S. lawmakers criticized it as unsafe and misleading.

Packers use carbon monoxide to stabilize the color of meat

Democrats said the process misleads consumers by making the products look safer than they really are

On Tuesday, discount retailer Target Corp asked USDA for approval to add a warning to the label of meat that has been treated with carbon monoxide sold in its stores.

Rep. Marsha Blackburn, a Tennessee Republican, defended the practice on grounds that it reduces the need for human handling and limits the chance of adding bacteria to the meat.

Officials at the Food and Drug Administration and U.S. Agriculture Department said they stand by the safety of the carbon monoxide practice