Guest Columns

Dairy Research

Raw milk consumption continues to pose serious food safety risks

John Lucey

John Lucey, director of the Wisconsin Center for Dairy Research at the University of Wisconsin-Madison, contributes this column for Cheese Market News®.

It’s very surprising to me that many states across the U.S. have, in recent years, passed legislation to allow for greater access and sales of raw fluid milk. Consumption of raw fluid milk is a food safety risk due to routine (unintended) contamination of milk with pathogens that are commonplace in the farm environment.

Better training of farmers and more frequent testing cannot guarantee that raw milk will be free from pathogens. Some raw milk groups have claimed that the use of their specific training and other approaches effectively makes raw milk a very low-risk product. Unfortunately, that is not accurate, and just wishful thinking.
One large raw milk producer in California that closely follows these trainings/approaches has had more than 11 outbreaks or recalls since 2006, including three recalls/outbreaks in 2023 alone. (That producer also recently was featured by Bill Marler in his blog on food safety under the title: “Raw Milk — A Sickening Elixir.”) I doubt that most food companies would survive with that track record.

It is also important to note that these raw milk recalls are mostly initiated when state regulatory groups conduct their infrequent testing of these milks and detect the presence of pathogens. It is unknown how many more recalls would have been initiated with more frequent, e.g., daily or weekly, testing of raw milk. The Center for Dairy Research (CDR) tracks all raw milk recalls and outbreaks in the U.S. and, so far in 2024, there already have been five.

In addition, raw fluid milk can’t be safely screened by testing. Pathogen testing can take several days for sampling and analysis, yet most raw milk already may be consumed since it is a short-shelf-life product.

Typically, it takes several days just to get a presumptive result in a sample, and then another couple of days are needed to confirm the presumptive result. It is also possible that the number of pathogens present in raw milk is too low to be detected by the testing method, but even small numbers of pathogens still may be sufficient to cause illness. Another limitation of testing raw milk is that it is impossible to test for every single type of human pathogen. Emerging, previously unknown or unusual pathogens also are a significant concern with raw milk. Pasteurization destroys them all.

To reduce risk, some have suggested testing raw milks for a couple of pathogens for a few weeks prior to onboarding a raw milk producer. However, this method would only tell us whether there were pathogens in those couple of samples. It is a flawed approach; it does not reflect the reality that most raw milk contamination is a sporadic issue.

Furthermore, even if testing doesn’t find pathogens in a raw milk sample, that doesn’t mean that the milk is necessarily safe going forward. Temperature abuse and/or an extended time from milking to human consumption can allow pathogen numbers to increase to levels sufficient to cause illnesses. There isn’t such a thing as a “safe” raw milk producer. In some studies/surveys, almost a third of all milk samples contained at least one type of pathogen. As consumers, we should assume that raw milk is likely to contain pathogens. The prevalence of pathogens in milk is influenced by numerous factors, including farm size, number of animals on the farm, hygiene, farm management practices, milking facilities, season and others. Raw milk can be contaminated with pathogens even when sourced from clinically healthy animals. Conversely, even if a farm is following good hygienic practices, cleaning udders, etc., the cow itself can carry and shed pathogens into the milk.

Sadly, the consumers that are most at risk of illness from raw fluid milk consumption are children, pregnant women and immunocompromised individuals. Data from the Centers for Disease Control and Prevention (CDC) shows that of the reported illnesses from drinking raw milk that occurred from 1998-2018, 48% were among people 19 years and younger. Children are more sensitive to pathogens because their immune systems are not as well developed.

A number of pathogens are commonly found in raw fluid milk like Listeria monocytogenes, Campylobacter
jejuni, toxigenic strains of E. coli and others. Exposure to these pathogens, even in very small bacterial counts, can result in serious illness or even death.

A major pathogen of concern in the dairy industry is Listeria monocytogenes, which can grow at refrigeration temperatures. This pathogen has been in the news recently as it has been associated with several recent raw milk recalls. For immunocompromised individuals, as well as children and pregnant women, Listeria monocytogenes has a low infective dose and in sensitive individuals can cause sepsis and has high mortality rates.

Campylobacter jejuni is another common pathogen found in raw milk. It can result in diarrhea in infected individuals. However, infection with Campylobacter jejuni is also recognized as a common cause of the serious neurological disease, Guillain-Barré syndrome.

E. coli, specifically toxigenic strains of E. coli, is another dangerous pathogen associated with raw milk recalls. It has a low infective dose and produces a Shiga toxin. In sensitive individuals, such as children, E. coli infections can cause potentially life-threatening complications, such as, hemolytic uremic syndrome (HUS).

Still, some consumers are attracted to raw milk because of some falsely claimed health or nutritional benefits. At least five major published reviews have reported that pasteurization of milk does not cause any significant change in the nutritional quality of milk. Pasteurization does not cause any change in protein quality.

Pasteurization may cause very minor losses (less than 10%) of vitamin C, folate (vitamin B9), vitamin B12, vitamin B6 and thiamine (vitamin B1). Of these vitamins, milk is an excellent source of only vitamin B12; milk has only low concentrations of most of the vitamins listed previously.

One of the most commonly claimed health benefits of raw milk consumption is that it reduces risk of developing allergies and asthma in young children. This suggestion came from findings that showed that there was a statistical correlation with traditional farming communities (which retain very high levels of raw fluid milk consumption) and lower risks for children developing asthma and allergies. However, correlation is not causation, and despite many investigations, no component in raw milk has been demonstrated to be protective for asthma/allergies. Recent work from the University of Wisconsin-Madison has compared children from two very traditional farming communities, the Amish and Old Order Mennonites. Both had very high levels of raw milk consumption, but the Amish had much lower prevalence of allergies likely due to their higher levels of contact with animals and barns. A farming lifestyle seems to be involved in providing a protective effect.

This year, we celebrate the 100-year anniversary of the introduction of the Pasteurized Milk Ordinance (PMO), which helped to dramatically reduce the incidence of milkborne outbreaks from over 25% of all outbreaks related to foods in 1938 to less than 1% today. The sale and consumption of raw fluid milk is a step backward for the dairy industry, and, unfortunately, raw milk is becoming a growing cause of illness in our children.
For more information, visit CDR’s Raw Milk Fact Sheet at


The views expressed by CMN’s guest columnists are their own opinions and do not necessarily reflect those of Cheese Market News®.

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