Every month brings another horror story about recycled food.

Last month, a Snokist processing plant in eastern Washington State was reported to have packaged moldy, “retreated” applesauce for sale in the US. The USDA was slammed for not stopping the process whereby Snokist skimmed mold off the top of vats of applesauce, heated it in an unscientific attempt to kill the mold, and packaged it for sale in supermarkets and for use in the nation’s school lunch program. Fortunately, a low-level USDA inspector contacted the FDA and Snokist was forced to stop recycling food waste.

But now comes another USDA horror story: the purchase of 7 million pounds of pink slime for use in the school lunch program.

What is pink slime? First, let’s talk about what it’s not.

When you eat a hamburger, you’re expecting to get ground muscle tissue—the trimmings from the most nutritious part of the animal. You will also get some fat, because the leanest meat from the animal is cut into steaks, and the less lean meat is usually ground into hamburger. For health reasons, consumers like their hamburger to have less fat and more lean. Food processors have always looked for inexpensive ways to boost the lean content of hamburger.

Now there’s a way for other lean parts—not just muscle tissue—to make it into your hamburger. The marketing names for pink slime include “Lean Beef Trimmings” and “Lean Finely Textured Beef.” What those names mask is that pink slime is composed of connective tissue, including tendons, ligaments, and intestines, combined with stuff that’s fallen onto the slaughterhouse floor.

Ask anyone who’s worked in a slaughterhouse if they would eat the stuff that falls onto a slaughterhouse floor, and you’ll hear a horrified “Never!” followed by a gagging sound. Ten years ago, scraps from filthy slaughterhouse floors were sent to rendering plants or used in dog food or chicken feed. Not anymore. Now the USDA has deemed it fit for human consumption.

How can this be? Well, food companies now treat the gunk on slaughterhouse floors with ammonium hydroxide, a pink chemical that’s supposed to kill pathogens like E. coli and salmonella. But tests done since 2005 on pink slime have found E. coli in at least 3 separate batches of pink slime, and salmonella 48 separate times.

An estimated 76 million people contract food-borne illnesses every year in the United States, according to the CDC. That means nearly one-quarter of all Americans will get sick from eating contaminated food in 2012. Hamburger is always high on the list of suspect foods.

But there’s a bigger health crisis here, one that’s not being discussed. Pink slime is not as nutritious as traditional ground beef, according to Gerald Zirnstein, a microbiologist who used to work in the USDA Food Safety Inspection Service. He and his colleague, Carl Custer, who also worked for 35 years in the Food Safety Inspection Service, have deemed it a “high risk product” that’s not nutritionally equivalent to ground beef. Said Custer: “My main objection was that it was not meat.”

When the human body eats non-nutritious food, the body craves more food to make up for the lack of vitamins and nutrients. Dietitians widely recognize non-nutritious food as a major contributor to the obesity epidemic in the US. It’s not much of a stretch to say that pink slime plays a key role. This non-meat waste product can be found in 70% of ground beef sold in the US, and the burgers-and-fries diet is widely reviled by dietitians, not just for its high fat content, but also for its lack of nutrients.

When McDonald’s, Burger King, and Taco Bell have banned pink slime from their food, you know it’s pretty bad stuff.

But food-borne health issues go beyond recycled waste products like pink slime. The pink chemical ammonium hydroxide has been used to wash most ground beef since the 1990’s—long before pink slime came along. Traces of ammonium hydroxide often remain in ground beef for sale in the supermarket, whether it contains pink slime or not.

Any chemical that’s strong enough to kill E. coli can do damage to the beneficial bacteria in the human stomach and intestines. Loss of beneficial bacteria is suspected to be a contributing factor in the rising rates of obesity, but also in an increase in other digestive tract disorders. And digestive tract diseases of all types afflict up to one-third of the US population, according to 2004 statistics from the National Digestive Disease Information Clearinghouse.

Most victims of digestive tract diseases are elderly, but many of us have heard about anecdotal cases of young people, including teens or children, who’ve been diagnosed with digestive tract disorders with unknown causes. Some of these cases are severe, requiring surgery or long-term medication and highly restrictive diets, and the outcome is not always a positive one.

We should be taking a much closer look at our food supply, and we should listen to whistleblowers from the USDA, like Zirnstein and Cutler, who criticize the department for being too friendly to food processors. If the USDA is supposed to be a guardian of public safety, they’re doing a terrible job of it.

An online petition calling for the USDA to drop pink slime from the nation’s school lunch program can be found at http://www.change.org/petitions/tell-usda-to-stop-using-pink-slime-in-school-food.