It’s looking like the days are numbered for the FDA’s 60-day rule. Introduced in 1949 to protect public health, the regulation requires all cheeses—domestic or imported—made with unpasteurized milk to be matured for at least 60 days. Conventional wisdom held that cheeses aged that long would be too dry, acidic or salty to harbor deadly bacteria like Listeria and Salmonella.

But pathogens evolve and so must our tactics, scientists now say. Although aged raw-milk cheese from licensed creameries has an excellent safety record, regulators believe they need a failsafe approach. The 60-day rule is “not efficacious,” said Dr. Nega Beru, head of FDA’s Office of Food Safety, in a presentation to the American Cheese Society conference last month. “We are looking for alternative measures to control pathogens.”

Dr. Beru’s talk coincided with the FDA’s release of the results of its extensive testing initiative. Over almost two years, the agency collected more than 1,600 samples of aged raw-milk cheese, domestic and imported, and tested them for pathogens. Researchers detected Salmonella in three samples; Listeria monocytegenes in ten samples; E. coli O157:H7 in none; and another strain of pathogenic E. coli in one. They found no evidence of any illnesses that tracked to these cheeses.

Although we might wish all those numbers to be zero, even the FDA report concedes that the Salmonella and E.coli prevalence was low “and similar to the contamination rates in many other foods.” The Listeria result—a violation rate of .67 percent—concerns the agency, although cheeses made with pasteurized milk might fare no better under similar scrutiny.

Wisconsin cheesemaker Andy Hatch had a different take on the Listeria rate. “That’s awfully low,” said Hatch, who makes the acclaimed raw-milk Pleasant Ridge Reserve. Given that a single creamery generated most of the domestic violations, Hatch considers the outcome impressive.

The demise of the 60-day rule seems certain; less clear is what will replace it. Some cheesemakers, like Hatch and Jasper Hill Farms’ Mateo Kehler, believe end-product testing at the creamery could work. The FDA, in collaboration with Health Canada, has already studied that approach, with satisfying outcomes.

“Testing every batch of raw-milk cheese for Listeria and destroying the positives resulted in a lower risk to public health than producing pasteurized cheese and not testing,” says Hatch, who is familiar with the research. “Rather than an arbitrary aging limit, a testing program could prove with reasonable certainty that every batch sold is free of Listeria.” And, presumably, such testing might “green light” young raw-milk cheeses that the current 60-day rule prohibits.

Or U.S. regulators could look to Great Britain, where raw-milk cheesemakers have collaborated with government and scientists to develop a detailed guide to best practices. Carlos Yescas, program director for Oldways Cheese Coalition, favors this approach because it’s proactive, not reactive.

“We need to move away from rules that, if you don’t comply, you get shut down,” says Yescas. With an agreed-upon set of processes that ensure safe cheese, regulators can review a creamery’s methods and alert them to shortcomings before problems arise, he says.

The problem, says Kehler, is that those steps don’t exist for semisoft cheese. Controls that would make a cheese microbiologically safer—like adding more salt or removing moisture—would make it unpalatable.

A committee of the American Cheese Society is currently writing a best-practices document, with input from the FDA. But guidelines, no matter how widely adopted, are not likely to convince regulators that raw-milk cheeses are safe. In the meantime, observers believe that the status quo will prevail for a few months longer. Sometime after a new administration settles in, the old rule should learn its fate.

“They will change it,” says Kehler. “They’ve made that clear."