By Lorrie Baumann
The U.S. Food and Drug Administration is asking for comments and data about the safety of cheese made from unpasteurized milk with a view to regulating more carefully how cheesemakers produce raw milk cheeses. “We are taking this action in light of scientific data on potential health risks associated with consumption of cheese made from unpasteurized milk,” according to an FDA notice published on August 3.
The public has until November 2 to submit either electronic or hard-copy comments and scientific data and information to the FDA. Electronic comments should be submitted to http://www.regulations.gov with reference to Docket Number FDA-2015-N-2596.
The FDA is relying on a 2012 review of outbreaks of foodborne illness that occurred in the U.S. between 1993 and 2006 that pointed a finger directly at cheese, and to cheeses made from unpasteurized milk in particular. According to that study by scientists from the Centers for Disease Control and Prevention, the review included 121 outbreaks of foodborne illness involving dairy products between 1993 and 2006, and among these, 73 (60 percent) involved nonpasteurized milk and resulted in 1,571 cases of illness and two deaths. Out of the 65 outbreaks involving cheese, 27 involved cheese made from raw milk, a figure that’s particularly significant since less than 1 percent of the dairy products consumed in the U.S. during the time period were made from unpasteurized milk, according to the FDA. The 38 outbreaks involving cheese made from pasteurized milk resulted in 744 illnesses and 1 death, while the 27 involving cheese made from raw milk resulted in 641 illnesses and two deaths.
According to the 2012 study, all of the illnesses involving nonpasteurized dairy products were caused by bacteria, although a number of species of bacteria were involved, including Campylobacter species, Salmonella species, E. coli, Brucella species and Shigella species. Three of them were caused by Listeria. That suggests that the contamination more likely came from the dairy environment than from the humans who handled the milk, who’d have been more likely to pass along viruses than bacteria.
The FDA notes in its call for data that cheeses made from unpasteurized milk are required by federal regulations to be aged, typically for 60 days or more. This was presumed to reduce the risk that disease-causing bacteria would still be alive in the cheese when it was eaten, but recent research has shown that the 60-day aging period for soft ripened cheeses might actually increase the risk that the cheese will cause listeriosis, the infection caused by Listeria, by giving more time for the bacteria to multiply. It is not legal in the United States to sell soft ripened cheeses made from unpasteurized milk outside the state in which they were made, but such cheeses can be made and sold in states that permit sales of unpasteurized dairy products.
Dr. Catherine Donnelly, a Professor of Nutrition and Food Sciences at the University of Vermont, is among those who agrees that the FDA should take another look at whether the 60-day aging period for raw milk cheeses does more harm than good in the case of soft ripened cheeses. “The 60-day aging rule should not be applied to a soft-ripened cheese,” she said. The rule makes sense in the case of hard cheeses made from raw milk, she said. “As cheese ages, the pH goes down and the moisture declines, and you’re creating that inhospitable environment [for harmful bacteria].” But in the case of soft cheeses such as a brie or Camembert, the surface molds that are essential to creating the cheeses produce amine products that raise the pH of the cheese, creating an environment in which bacteria can thrive, she said. “Mature ripened Camembert has a pH about 7 [which is neutral]. As the pH goes up, you start getting conditions that allow the growth of Listeria. That’s why in cheeses like brie and Camembert, you get very high levels. The FDA should never have applied the 60-day aging rule to a soft-ripened cheese, but it’s part of our Code of Federal Regulations. That’s not a very good rule from a safety standpoint.” The good news for cheesemakers, however, is that FDA’s soft cheese risk assessment shows that if every batch of raw milk soft ripened cheese is tested for Listeria, the risk is actually lower than that for soft ripened cheese made from pasteurized milk. Donnelly also points out that Food Standards Australia New Zealand conducted a 2009 Risk Assessment of raw milk cheese, which concluded that “Campylobacter spp. [species] were found to be a negligible risk in both raw milk extra hard and Swiss-type cheeses. The presence of Campylobacter spp. was not assessed in raw milk Cheddar, blue, Feta or Camembert cheeses. However, Campylobacter spp. are unlikely to grow in milk or cheese, as their growth requires reduced oxygen tension and temperatures between 32 – 45°C and they do not survive well under slightly acidic conditions, or in the presence of greater than 2 percent salt.”
There’s little question that soft cheeses made from raw milk are potentially more dangerous than hard cheeses made from raw milk. Studies indicate that the risk of illnesses may be orders of magnitude higher for unpasteurized dairy products than for those that have been pasteurized. “In France, you can’t legally sell Camembert beyond 55 days. Why? Because it’s too dangerous,” Donnelly said. She’s concerned that the FDA might now decide that no cheeses should be made from raw milk even though the harder cheeses are much safer. “I’ve studied listeria for a long, long time. I share the concern about the growing incidence of listeria in elderly and susceptible population. Soft cheese is just one category of products that the FDA has determined to be a risk,” she said. “I am just concerned that this might carry over to other varieties of cheese made from raw milk that have been shown to be very microbiologically safe – things like the harder cheeses made from raw milk.”
She points to a 2014 study conducted by scientists affiliated with the Centers for Disease Control and Prevention that distinguishes the types of cheeses involved in 90 outbreaks caused by cheese between 1998 and 2011.While 38 of the outbreaks (42 percent) were caused by cheese made from unpasteurized milk, 44 (49 percent) were caused by cheese made from pasteurized milk. Queso fresco was the most common cause of the outbreaks, including 18 due to cheese made from unpasteurized milk and one due to pasteurized cheese. An additional seven outbreaks reported an unspecified type of soft Mexican-style cheese. “Homemade” cheese was the second most common type reported for the outbreaks due to raw milk cheeses.
The soft unaged cheeses imported from Mexico were responsible for 13 outbreaks – more than a third of all outbreaks associated with cheese during the period. Nine of those were caused by Listeria. In five outbreaks, all due to cheeses made from unpasteurized milk, the cheese was produced or sold illegally. Commercial importation from Mexico of cheese made from unpasteurized milk is illegal unless the cheese has met FDA aging standards, although travelers are allowed to bring in limited amounts of raw milk cheeses for personal use. However, these raw milk cheeses imported for personal use are often illegally sold once they’re in the United States.
The 2014 study concluded that “In addition to using pasteurized milk, soft-cheese-making facilities need to ensure strict sanitation and microbiologic monitoring. Labeling of cheese should include whether the milk used to make it was pasteurized or unpasteurized, whether the cheese was aged and for how long, and the license number of the production facility.” The report adds that, “Efforts to reduce production and sale of illegally manufactured cheeses as well as continued binational collaborations are needed to address the issue of illegal cheese importation.”
“This is where the real risk lies” stated Donnelly.