In 2004, the FDA approved the use of carbon monoxide to keep meat looking red, fresh and more appealing to consumers. This process allows meat to be packaged right after animals are slaughtered and eliminates the need for butchering once the meat is delivered to stores. Essentially, the carbon monoxide replaces oxygen, which can act to turn fresh meat brown. This natural color change doesn't indicate spoilage, but brown meat is less appealing to consumers. The carbon-monoxide-treated meat is not available everywhere but reportedly is sold at some supermarket chains. There is nothing on the package that indicates that the meat has been treated with carbon monoxide.
The FDA approved use of carbon monoxide as a color "fixative" rather than a color "additive," which would have required an extensive review.
Early in 2006, the FDA was asked to rescind its decision in a petition filed by a Michigan producer of a food extract that also helps keep meat looking red. Consumer groups including the Consumer Federation of America and the advocacy group Safe Tables Our Priority have supported the petition. It is likely that some self-interest motivated the Michigan firm, but a good case can be made that fixing the color of meat is a deceptive marketing practice: it may suggest that meat is fresh when it isn't.
In fact, color is a poor indicator of freshness; meat can turn brown and still remain perfectly tasty and safe to eat. But opponents of using carbon monoxide to "fix" the color argue that by keeping meat looking fresh beyond its "sell by" date the process can mask spoilage. They also say that if there is any lapse in refrigeration, treated meat could spoil but would still look fresh. (By the way, the European Union has banned use of carbon monoxide specifically for this reason.) In short, opponents argue that use of carbon monoxide itself is safe, but the meat may not be by the time you open the package.
If you object to the use of carbon monoxide as a color fixative, inquire at your market's meat counter to discover your store's policy (because such policies can change quickly, if we listed participating stores here, the information might be out of date by the time you read it). You can also contact your elected representatives in Congress and make your views known.
Andrew Weil, M.D.