By Sarabeth Lowe, MPH

Ms. Lowe is a Communication Specialist at the University of Delaware Disaster Research Center.

The Revival of Raw Milk is a two-part series focusing on a growing movement in the US: the consumption of raw milk. Part I describes the historical and cultural context around raw milk and explains how pasteurization, a groundbreaking scientific discovery that revolutionized food safety, works to protect public health. Part II will delve into the current ethos surrounding raw milk, addressing common misconceptions and myths, the latest trends in epidemiological data, and its impact on both personal and public health.

While milk has long been a staple in the American diet, the US’s relationship with it has been a turbulent one. It has been a public health menace, a symbol of patriotism, and a nutritional, ethical, and environmental conundrum.¹ Now, its entering a new chapter. The US is experiencing a blast from the past as raw milk—that of cows, sheep, or goats that has not been pasteurized—returns to the scene. Estimates from Circana, a market research firm, report that sales of raw milk spiked by 17.6 percent in 2024, and, according to the latest available data, about 11 million Americans drink raw milk.^1–3 This trend persists in spite of consensus from numerous agricultural, food safety, and public health experts, who agree that the risks of consuming raw milk significantly outweigh any of its potential health benefits.^3–9 

Decades of research and discovery have yet to yield substantiated evidence of the benefits of raw milk.¹ It has found just the opposite. This is supported by the historical record. Until the 20th century, milk was a perpetual threat to public health.^1,3,10–12 In 1858, The New York Times went as far as proclaiming that milk was a danger, “becoming intolerable to civilized society.”^1,13 As late as 1938, milk-borne diseases were responsible for 25 percent of all foodborne illness outbreaks.¹⁴ By 2016, however, milk and dairy products were responsible for less than one percent of these outbreaks. Its actually one of the safest foods we consume in the US today.¹ This is the story of how we got here.

The Dark Side of Dairy

Humans have been domesticating milk-producing animals and consuming dairy products for roughly 10,000 years.^3,11,16 This moment, when humans inserted themselves into the ancient relationship between milk-producing animals and their offspring, may have changed the course of human history. By diverting this source of nutrition into their own bodies, humans found a way to nourish themselves with grass and other tough plant material that they themselves could not digest directly.^17,18 This seemingly humble transition also profoundly impacted the human diet, as milk is a nutrient-dense food that was reliable and widely available. 

Milk remained a dietary staple even as humans transitioned from living in low-density, rural settings to more established agricultural communities. As people moved, their cows, sheep, and goats moved with them. To keep up with the demand for milk in cities, the dairy industry also brought small herds with them.³ Living closely with animals, however, presents several risks. Some of humanity’s nastiest scourges, including smallpox, tuberculosis, and measles, likely originated from domesticated animals.^17–19 In the 18th and 19th centuries, the Industrial Revolution spurred urbanization and mass migration, which required many perishable food products, including milk, to be shipped long distances. Milk spoilage quickly became a major vector of disease and a demanding public health issue.^{1,3,10–12–14,17}

From Pasture to Pasteur

Foodborne disease has been a global public health issue throughout human history. In 1856, an alcohol manufacturer commissioned a young microbiologist, Louis Pasteur, to determine the cause of souring in beet root alcohol.²⁰ Pasteur’s experiments established a direct cause-and-effect relationship between bacteria and the souring of wine into vinegar. This groundbreaking finding led him to recognize that microorganisms functioned as the agents of fermentation, and Pasteur later discovered that heating wine and beer killed the organisms that caused spoilage.^21,22 On April 20, 1862, he completed the first successful test of this heating and cooling process, eventually patenting this method that we now know as pasteurization.²² This procedure went on to be applied to other perishable food products, including juice, eggs, and, most famously, milk.

What Is Pasteurization?

In broad terms, pasteurization is the process of applying a certain amount of heat for a certain amount of time to kill harmful bacteria. More specifically, it involves heating every particle of a food to a specific temperature for a continuous length of time in order to kill the most heat-resistant pathogen associated with that product.²³ The temperature and time of pasteurization processes are determined by the food’s acidity. This is why controlled scientific studies are necessary to determine the optimal length of time at a given temperature that will kill a specific type of bacteria.²⁴ When timed and heated properly, pasteurization can also greatly extend a product’s shelf life, especially when combined with refrigeration.

Several methods of pasteurization have emerged over the years, but they all lead to the same result: safe and pathogen-free milk. These are some of the traditional methods:^22,24,25

Vat pasteurization. This is the original method of pasteurization. Now, it is mainly used for making starter cultures in the processing of cheese, yogurt, and buttermilk. It involves heating liquid milk in a large tank for at least 30 minutes before cooling.

High-temperature short-time (HTST) pasteurization. HTST is currently the most common method in the US. It uses metal plates and hot water to raise temperatures to at least 161°F for at least 15 seconds, followed by a short period of rapid cooling. This process is often used to sterilize dairy products, but it can also be used to pasteurize more viscous foods, such as soups and sauces. These pasteurized products have a refrigerated shelf life of approximately two weeks.

Higher heat shorter time (HHST). HHST has a process similar to that of HTST but uses slightly different equipment and higher temperature for a shorter amount of time.

Ultra-pasteurization (UP). Also similar to HTST, UP involves heating a liquid to at least 280°F for one to two seconds. This method of pasteurization is most commonly used in milk, but it is also applied to fruit juices, cream, soy milk, yogurt, wine, soups, honey, and stews. UP products provide a refrigerated shelf life of approximately three months.

From Raw Milk to Regulation

In the last 160 years, pasteurization practices have been adopted worldwide. According to a 1924 US Public Health Service article, milk was second only to water as a vehicle for transmitting disease in the US.^15,26 Since then, several laws and programs have been created to make pasteurization an innate part of dairy processing. In the years leading up to the 1924 Standard Milk Ordinance, pasteurization and other milk safety measures were not consistently applied on farms, in dairy plants, or during transportation. This law was two-pronged; it standardized dairy safety practices into a single model milk regulation program with uniform requirements and assisted states and cities in the voluntary adoption of programs designed to control milk-borne disease.^9,15,26–28 

This reform continued for several decades. In 1910, Ernst Lederle, the New York City Commissioner of Health and a chemist, introduced mandatory pasteurization of milk.^22,23,29 After observing a marked decrease in milk-borne illnesses and deaths, other cities and states also began requiring pasteurization. The National Conference on Interstate Milk Shipments (NCIMS) was formed in 1946 to maintain an effective and efficient system of regulating the interstate shipment of milk products.^15,30–33 Thirty years later, the federal government required the pasteurization of milk used in any interstate commerce, and the US Food and Drug Administration and NCIMS established the State Cooperative Milk Safety Cooperative Program, which still exists today.^22,27,28,33

The 1924 Standard Milk Ordinance has evolved into the current Grade “A” Pasteurized Milk Ordinance (PMO).^28,32–35 This updated policy is much more comprehensive and thorough than its original form. It is also highly collaborative, requiring the FDA, states, and the dairy industry to work together.¹⁵ The PMO is revised every two years, in odd-numbered years, by the US Department of Health and Human Services, Public Health Service, and the FDA to reflect the latest science and pasteurization technology.^27,34 Thanks to the PMO, milk and dairy products produced in the United States are among the safest in the world.^15,27,33 

However, not all milk in the US is required to be pasteurized. At the federal level, only milk sold through interstate commerce is required to meet this standard. In other words, any milk bought, sold, and transported across state lines must be pasteurized.^5,36 However, the FDA does not prohibit an individual from purchasing raw milk and personally transporting it across state lines for their own use. States are left to determine how to regulate the sales of raw milk in intrastate commerce. This patchwork of laws is why regulation varies from state to state. According to the National Agricultural Law Center, 18 states outright ban the sale of raw milk, wh ile 32 allow its sale under certain conditions.³⁶ In 2025, three states—Arkansas, Utah, and North Dakota—passed laws that expand access to raw milk.^36–40

Lingering Heat Over Pasteurization

Its difficult to overstate the profound impact Pasteur’s discovery has had on food safety and human health. Pasteurization has reduced the proportion of milk-borne illnesses attributable to raw dairy products from approximately 25 percent before pasteurization to approximately two percent in the twenty-first century.³⁵

According to an FDA evaluation, only one person gets sick per every two billion servings of pasteurized milk or milk products consumed in the US.^15,41 At the same time, a growing body of research continues to point toward the risks of raw milk. A 2018 study found that it was responsible for nearly three times as many hospitalizations as any other food-borne illness.⁴² Another study found that unpasteurized dairy products cause 840 times more illnesses and 45 times more hospitalizations than pasteurized products.⁴³

Despite these advancements, jaw-dropping statistics, and numerous foodborne outbreaks, controversy still simmers over the perceived benefits of raw milk. The science is clear on its risks, but the public’s perception of these risks is not.^3,6,44 Although only a fraction of Americans consume raw milk, researchers estimate that roughly 11 million Americans, or 4.4 percent of the US population, do so—and its implications for personal and public health remain the same.^2,44 If the popularity of raw milk continues to rise, Americans may need to consider that a public health crisis once thought to be a thing of the past may be looming in the future.

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