When you pick up a package of ground chuck or London Broil, you check the “sell by date,” presumably, but you also look for visual cues to tell you how fresh the meat is. As meat begins to spoil, it turns an unappealing grayish-brown. Most of us know enough to skip the suspiciously colored sirloin.

But the meat industry has been quietly manipulating the appearance of meat by using carbon monoxide as a “pigment fixative,” a process that enables red meat to retain its fresh pink color even when spoilage may have occurred.

Ann Boeckman, a lawyer whose firm represents the companies that helped pioneer this technology, defended the use of carbon monoxide, telling a Washington Post reporter, “When a product reaches the point of spoilage, there will be other signs that will be evidenced-for example odor, slime formation and a bulging package-so the product will not smell or look right.”

Good to know! If the meat is bursting out of its packaging, oozing slime, and stinks, disregard that nice healthy pink hue.

But if this practice is so safe, how come it's been banned by the European Union? The European Commission's Scientific Committee on Food concluded that the use of carbon monoxide as a color stabilizer in meat and fish “may mask visual evidence of spoilage.”

The FDA has never formally approved the gas's use as a color fixative, and now consumer advocates are accusing the FDA of permitting the practice without conducting a formal evaluation of its impact on consumer safety.

At the very least, wouldn't you like to know if your meat's been treated? According to the Washington Post, “no one knows how much carbon-monoxide-treated meat is being sold; the companies involved are privately held or keep that information a secret.”

The meat industry claims it loses $1 billion annually by having to mark down or discard meat that's still fresh and safe to eat but not such a pretty shade of pink. The market for so-called “case ready” meats, prepackaged to eliminate the need for a butcher behind the counter, is a rapidly growing segment of the meat industry, approaching sales of $10 billion.

Tyson foods, one of three meat packagers who've received permission from the FDA to use carbon monoxide, has just opened a $100 million plant in Texas to “churn out more case-ready “modified atmosphere” packaged meats,” Steve Kay of Cattle Buyers Weekly told the Washington Post, so the supermarkets, which are probably already flooded with this stuff, are going to be selling even more of it soon.

I'm glad I buy my meats from small local farmers or Whole Foods, which sells fresh, not pre-packaged, responsibly raised beef. But if you don't live near a farmer's market, Whole Foods, or a good local butcher that you trust, what are your options? Well, for starters, get used to the idea that, thanks to the wonders of technology, you can no longer judge a steak by its color.