Microbiologists aren't convinced that a single negative test proves much. "You are looking at a very small sample size relative to the lot, so you probably are going to miss it if it's in there," says Ewen Todd, a professor at Michigan State University.
Todd says the government could have tested the orders more than once. It did not, records show. "In this case, you know (salmonella) was in the system, so there's a good chance it was in that (school lunch) product," Todd says. "If they wanted to be certain, they at least would have done a lot more testing. …They should have tripled the number or done tenfold the number."
Others agree. "That blows my mind that they would accept those lots without a lot of additional testing," says Barbara Kowalcyk, a biostatistician at the Center for Foodborne Illness Research & Prevention. Kowalcyk understands the risks children face from dangerous pathogens. In 2001, her 2-year-old son, Kevin, died of complications from an E. coli O157:H7 infection.
•The beef used to make school products is segregated from commercial products, so any contamination in commercial products should not carry over to the beef produced for schools.
The meat for schools "is made from raw beef source material that is targeted solely for AMS product," explains Jerold Mande, the USDA's acting undersecretary for food safety. "The source materials and the finished product are subject to AMS testing protocol and required to meet all contractual specifications."
AMS tests the meat destined for schools twice. The first test screens the "source material" — the raw chunks of beef that have yet to be ground. The second test examines the beef after grinding but before it is shipped.
Shortly before and during the dates of the recall, government inspectors had found evidence of problemsin the beef at least six different times — in both the "source material" and the finished product, documents obtained by USA TODAY show.
When the recall committee met Aug. 5, the members knew, for instance, that "source material" used by Beef Packers had screened positive for pathogens on June 2 and June 12.
They also knew that inspectors had identified problems with "source material" at Beef Packers on May 28, June 16 and June 23.
They knew that a test on one sample from ground beef meant for schools, taken on June 9, also came back positive — this time for the Newport strain.
They knew that the Newport strain had surfaced in the plant before, in a May 21 test on commercial beef.
And they knew of another matter involving the company. Inspectors had found a different strain of salmonella at Beef Packers earlier that summer.
Experts say the indicators were clear. "Obviously the plant had an ongoing contamination problem," Kowalcyk says. Adds Marsden: "It appears they had a systemic problem."
•The recall committee had no evidence that anyone had gotten sick from beef produced on the days products for schools were made.
The USDA recall committee determined the scope of the recall by looking at dates on which the commercial ground beef implicated in the illnesses had been made: June 5, 8, 10, 11, 12, 15, 19, 22 and 23.
The food sent to schools was "produced on days not associated with any illnesses," Mande says: June 6, 13 and 20.
That explanation offers little solace, given how production for the school lunch program works.