According to CIDRAP, only two plants actually failed to meet the USDA's standard for Salmonella in chicken: a maximum of 20% of samples contaminated. At the other 19 plants, between 10% and 20% of recent samples had Salmonella, according to the USDA Food Safety and Inspection Service (FSIS).

The plants listed are in 12 states and Puerto Rico. The two that failed the standard are a Pilgrim's Pride Corp. facility in Ellijay, Ga., and a Tyson Foods Inc. plant in Center, Tex., according to the FSIS.

The USDA had said in January that it would begin listing facilities with higher Salmonella rates on Mar 28. The move is part of a control initiative the USDA first announced about 2 years ago, after several years of increasing contamination rates. About 16% of broiler chicken samples tested positive for Salmonella in 2005. The initiative includes a "risk-based" sampling program, in which FSIS focuses more of its sampling on plants that have higher Salmonella levels.

The naming of the 21 plants came on the heels of a report in which the consumer group Food and Water Watch listed 27 broiler chicken facilities in 17 states that failed at least one round of Salmonella testing between January 2006 and January 2008 by having a contamination rate higher than 20%. The nonprofit group used a Freedom of Information Act request to obtain the information from the FSIS.

The group called on the USDA to publish Salmonella testing results for all chicken plants and to seek legislation to make its Salmonella standards legally enforceable. The organization also urged the agency not to reduce the frequency of sampling at plants that have the lowest contamination rates.