The USDA, with its Know Your Farmer, Know Your Food campaign, has some explaining to do. In a recent front-page story, Michael Moss of The New York Times explored the agency's endorsement of a company's process for treating beef trimmings with ammonia to kill salmonella and E. coli. The product is now used by McDonald's, Burger King, supermarket chains and the school lunch program.

The process, conducted by South Dakota-based Beef Products, Inc., didn't kill all the pathogens, according to government and industry records obtained by the newspaper, and departments within the federal agency didn't communicate about the findings.

But beyond that, there's the product itself. Called 'pink slime' by a USDA microbiologist, the 'mashlike substance' is made by liquefying the fat from the trimmings, extracting the protein in a centrifuge, exposing it to ammonia gas, flash-freezing it and compressing it into blocks or chips.

Federal officials agreed to the company's request that the ammonia be classified as a "processing agent" and not an ingredient that would be listed on labels.

So the questions: Is pink slime ground beef? How can we know our food if the ingredients label doesn't list everything that's in it?

And, a related story suggests that even if a state chose to label the product as something other than pure beef it may not be allowed. Avery Fellow writes in Courthouse News Service that an appeals court ruled that the Federal Meat Inspection Act trumps California's stricter Proposition 65. The court warned that companies risked USDA 'disapproval' if they created special labels, since the agency has said that

Proposition 65 warnings on government-inspected meat "would only confuse the public as to the wholesomeness of the meat."

The suit was brought by the American Meat Institute and the National Meat Association after a resident sent violation notices to eight meat processors and sellers accusing them of processing or selling ground beef and liver containing cancer-causing PCBs and dioxins without warnings that Proposition 65 would require. Whether the beef contained those toxins was not part of the lawsuit, so the questions linger.

If the origins, processing and contents of the items on our plates aren't part of 'knowing your food,' what is?