The Lingering Heat over Pasteurized Milk

milk bottles

Filling milk bottles, Briarcliff Farms, New York

All the fuss, as well as expense, did not go unnoticed by critics, who argued that the city had neither the money nor the infrastructure to institute mandatory pasteurization, as Straus and Jacobi advocated. Many complained that pasteurized milk featured an unpleasant “cooked” taste and grumbled over the diminishment of its “nutritive qualities.” Others contended that the real menace was lurking in dirty farms and distribution chains and urged a wholesale tightening of inspections. Still others accused the press of grossly exaggerating how often diphtheria and tuberculosis were really introduced into a household by the milkman.

These complaints bear an uncanny resemblance to those still voiced today: pasteurization may kill harmful germs, but it also destroys the properties of milk that resist them. The natural souring of raw milk by harmless bacteria is an important warning about its advancing age. And contamination can easily occur after pasteurization, creating a false sense of security and reducing the attention to cleanliness, rendering the milk all the more dangerous. Most residents agreed that pasteurized milk should be made available to poor children, for safety’s sake, and that excessive sterilization stripped milk of its nutritional value. But by the time The Outlook posed its milk-cooking question in 1907, little other common ground remained.

Nonetheless, the pasteurization movement was gaining steam. In 1909 Chicago became the first American city to enforce a compulsory milk pasteurization law, despite strong opposition at the state level. After vehement back-and-forth editorials, prolonged political maneuvering, and a typhoid epidemic blamed on raw milk, New York’s commissioner of health followed suit in 1914 with the enforcement of a previously adopted ordinance.

Seven years later the city’s infant mortality rate dropped to 71 deaths per every 1,000 births—less than one-third of the rate in 1891. Arguably, other improvements in health and hygiene also played a role in the decline. But the modernization of milk production ultimately settled the matter in favor of pasteurization. By 1938 bulk tanks on farms had begun replacing the ubiquitous milk cans. Pooling milk from multiple sources was becoming increasingly routine, a necessary step to keep pace with rapidly growing demand. But it also greatly increased the risk of contamination and furthered the call—and need—for pasteurization. By the end of 2007 only 4 states still permitted raw milk in their grocery coolers, though another 24 allowed on-the-farm sales.

Today milk-borne diseases are rarely fatal in most developed countries, though many remain on watch lists. Ailments like Brainerd diarrhea and Crohn’s disease have been tentatively linked to raw-milk consumption. Regarding the continuing risk from bacteria in cow’s milk contaminated by urine and especially feces, Cornell University’s Kathryn Boor notes dryly, “What we haven’t been able to do is to get cows to stop defecating.”

The ongoing pasteurization debate, often framed in terms of David versus Goliath, has pitted the Centers for Disease Control and Prevention, the U. S. Food and Drug Administration, the dairy industry, public-health officials, and most scientists against a looser grassroots alliance of farmers, organic-food enthusiasts, and non-profit advocacy organizations like the Weston A. Price Foundation. At its core the battle is all about weighing the potential of heat to kill disease-causing germs against its potential to kill milk’s health benefits and unique taste. Despite their differences, both sides largely agree that pasteurization is no substitute for clean, high-quality milk and that pooling milk from many sources requires heating to thwart the higher risk of contamination. From a 1997 survey of bulk milk tanks in Ontario, researchers calculated a one-in-three chance of finding pathogenic bacteria in raw milk randomly pooled from 10 farms. Nearly 3% of 1,720 samples tested were contaminated with Listeria. A smaller 2006 study found similarly high pathogen counts in bulk milk tanks from Pennsylvania. “I can understand how some people would understand it’s possible to make pathogen-free milk on a very small and very clean farm,” says H. Douglas Goff, a professor of food science at Ontario’s University of Guelph. “But scaling that up, that’s where it falls apart.”

The long-running standard of pasteurizing milk at 145 degrees or more for 30 minutes was set in 1957 to thwart its most heat-resistant pathogen, a highly infectious microbe named Coxiella burnetii that causes Q fever in humans. The dairy industry agreed to tweak the pasteurization process again when, in the aftermath of the 2001 anthrax attacks, a study envisioned the ease with which bioterrorists could taint a portion of the nation’s milk supply with the deadly botulinum toxin. Nonetheless, researchers concede that pasteurization may not kill all pathogenic microorganisms or fully inactivate every toxin.