The salmonella tests, ordered last June by the Clinton administration, were met with fierce opposition by the meat industry, which complained that the tests were burdensome and not scientific. The industry has since lobbied to scrap them.

In those tests, packages of meat were sampled randomly by the government for salmonella before shipment to schools.

Dr. Ken Clayton, acting administrator of the Agricultural Marketing Service at the Agriculture Department, said the current testing program did not ensure that schools were getting the safest food possible. In place of testing for salmonella, he said, the agency would institute a system to weed out suppliers who did not meet standards.

The agency will now require a second anti-microbial step at slaughterhouses, like an acid rinse, for plants that want to sell ground beef to the school lunch program.

In addition, grinders that do not meet the standards for cleanliness a certain percentage of the time will not be allowed to supply the school lunch program and other federal food programs.

It would be up to the schools to notify parents if they planned to serve irradiated hamburgers.

Irradiation shatters the genetic material of bacteria, killing them. The government began allowing beef to be irradiated a year ago, but relatively little has been produced, in part because of doubts about whether most consumers would accept it.

Mishandling of food, even if it has been irradiated or previously tested as untainted, can introduce harmful bacteria. And improperly handled raw beef can cross-contaminate raw food with which it comes in contact.

Salmonella causes 1.4 million illnesses and 600 deaths a year, according to the Centers for Disease Control and Prevention. While testing for salmonella would be eliminated, the Agriculture Department would continue its daily testing for E coli 0157H:7, except in products that had been irradiated.

It would also test for generic e-coli, which in itself is not harmful but which indicates the presence of fecal contamination. Even when a sample tests high for generic e-coli, however, it does not necessarily signal the presence of salmonella.

As of March 30, 1,436 samples had been taken by federal testers from more than 120 million pounds of ground beef. Of those, 130 samples were rejected, 75 of them because of salmonella, 10 because of contamination with E coli 0157H:7. The rest were rejected for high coliform counts or the presence of staphylococcus aureus.

The salmonella tests added to the cost of ground beef. Irradiation is expected to do the same, but it is not known by how much.

Until the Clinton administration adopted the science-based specifications last year, the only safety requirement for school-lunch ground beef was that it be produced in an Agriculture Department-certified processing plant.

Those specifications were enacted after a federal judge rebuffed the department's efforts last summer to close a Texas meat-processing plant based on random salmonella tests the department had conducted.

The plant supplied as much as 45 percent of the ground beef in the school-lunch program after it failed salmonella tests three times.

But the judge said the department lacked the authority to use such tests, and ordered that the plant remain open. It closed later last year, however, after the department decided to appeal the judge's ruling.

Since the rules became effective, salmonella contamination has dropped by as much as 50 percent, studies show.

"The requirements that were put into effect last year went further than the fast-food restaurants which have stringent limits but not zero tolerance," said Ms. Foreman.

NewYorkTimes.com