Recent recalls of raw-milk cheese have drawn increased attention to the U.S. Food and Drug Administration (FDA) rule that requires cheese made from unpasteurized milk to age for a minimum of 60 days before sale. For more than a decade, both the FDA and numerous food research groups have been working to answer the question: Is the “60-day rule” effective at eliminating harmful pathogens from raw-milk cheese? The short answer seems to be, “Not completely.” The FDA is considering a possible change to the rule. When the FDA first enacted the 60-day rule in 1949, no known disease-causing pathogens could survive the acidifying process of aging for more than a portion of the two-month process, and the 60-day time frame was selected to include an additional margin of safety. Half a century later, however, modern studies and illness outbreaks have shown that some harmful pathogens survive in raw-milk cheese for longer than 60 days. A study published in the December 2010 Journal of Food Protection found that a strain of E. coli O157:H7 survived at viable numbers for approximately 100 days in Gouda and cheddar cheese, while researchers detected trace amounts after more than 270 days. In November, an E. coli outbreak that sickened 38 people in five states was traced to Bravo Farms’ Gouda cheese made from raw milk and aged for at least 60 days. In December, gourmet raw-milk cheese from Sally Jackson in Washington state was the source of eight E. coli infections. “We didn’t have this problem 50 years ago,” said Kathy Glass, Ph.D., associate director of the University of Wisconsin-Madison’s Food Research Institute. “At the time, the 60-day rule made sense, but now we have new enemies in front of us and we need to have a different tactic.” The FDA has had the regulation under review for more than a decade. According to FDA spokesperson Sebastian Cianci, research questioning the effectiveness of the 60-day timeline first came to the agency’s attention in the late 1990s, but regulatory resources were focused on other matters in subsequent years. The agency has since completed the initial draft of its review of the rule, although Cianci could not specify a timeframe for any decisions regarding it. He said the rule has been under review “in earnest” for the past year and he called the delay helpful in allowing time for more researchers to investigate the issue. Researchers and cheese makers alike now speculate over what a revision to the law might entail. Glass suspects that the 60-day rule could become the “90-day rule” or the “120-day rule”. “The holding time works because of a combination of acidification and not having enough moisture. There’s definitely a science behind it,” she said. “E. coli is very acid-resistant and has a low infectious dose, but if you give it enough time it will still die off under otherwise good conditions.” Julie Steil, owner of River Valley Cheese in Fall City, WA, produces and sells a variety of cheeses made from both raw and pasteurized milk. She designs her raw-milk cheeses around the 60-day rule and said an extension of the minimum aging time would immediately impact her cash-flow and cheese-making process. “I make a raw-milk Tomme-style cheese and have perfected my recipes so the cheese peaks at 75 to 90 days,” she said. “If the cheese sits on the shelf aging longer than that, it will be ruined.” Aging extensions would reduce the shelf life of cheeses and increase the cost of holding inventory while it ages, Steil said. Her customers actively seek out River Valley’s raw-milk cheese for what she described as its “less processed” flavor. Others question whether the emphasis on aging time is the best approach to controlling harmful pathogens in raw milk products. In countries such as France, Germany and England, sale of raw-milk cheese requires no minimum aging time. Instead, safety measures focus on animal health requirements, hygienic milk collection and storage, fast cooling, and microbiological criteria (a maximum acceptable concentration of coliform bacteria). As with raw milk products sold in the U.S., those sold in these countries carry a specific label that usually explains the health risks associated with consumption. Of the 28 U.S. states that do not prohibit raw milk sales, many–including Washington, Idaho and California–have implemented microbiological criteria similar to regulations in Europe. Still, public health authorities such as the Centers for Disease Control and Prevention and food research professionals such as Glass stress caution when consuming raw milk products, even those aged to 60 days. “When I teach dairy safety classes, I’m quite clear to people that even though the regulations say ’60 days’, there are some cheeses that just might not be safe to make with raw milk–they’re going to need heat treatment,” Glass said. “But when you get the right cheese, like a two-year-old Parmesan made from raw milk, it’s so good. I do the necessary tests and know a bug won’t stand a chance in something like that.”