Most school lunches and fast-food burgers contain processed beef, a product considered so safe from contamination that the USDA exempted it from meat testing—but that has in fact been found to include E. coli and salmonella, according to a lengthy expose in the New York Times. The product, made from low-quality fatty trimmings, is injected with ammonia to kill pathogens, a process little known to the public because ammonia isn't listed as an ingredient in the beef.
The USDA approved the Beef Products company's novel ammonia-treatment process over the objections of department scientists who called the product "pink slime" and a safety risk. But the Times found E. coli has shown up three times since 2005 in Beef Products meat and salmonella 48 times. Further underscoring the weakness of government efforts to make hamburger safe, the school lunch program officials who found the contamination didn't inform USDA heads of the problem; they also told the Times that in testing all the meat they receive, Beef Products' results were worse than those of most of the program's other suppliers.