Milk pasteurization and dairy safety (United States, 1890s to 2012 and after)

American cities and then states moved from voluntary to mandatory pasteurization between 1908 and the 1950s, milk-borne outbreaks fell sharply, and the record still leaves open how much of the decline came from pasteurization versus refrigeration, inspection and cleaner water, while a raw-milk market remains legal in many states.

The record

What was at stake

• Before pasteurization became common, milk carried bovine tuberculosis and typhoid, scarlet fever and other infections. A 1924 Public Health Service article called milk "second only to water as a vehicle for transmitting disease" (as quoted by the FDA). (FDA, "Keeping Your Milk Safe: From the Grass to the Glass"; opened)
• Pasteurization means heating milk to kill pathogens. The current federal definition lists 145 F (63 C) for 30 minutes, 161 F (72 C) for 15 seconds, and several shorter, hotter pairs. (21 CFR 1240.61, via Cornell LII; opened)
• Pasteurization was not the only tool. Cities also tried tuberculin testing of cattle (introduced 1890), "certified" milk from inspected dairies (1892), inspection against watering and skimming, bulk tanks (1938) and tank trucks (1914). (International Dairy Foods Association, milestones; opened. An industry trade page.)

Timeline

Sources for the table: Wikipedia, Pasteurization (opened); American Heritage, "Saint Straus" (opened); Czaplicki, Social Science History 31(3), 2007 (abstract only opened).

The Chicago decision was slow and not a single vote

• Chicago's 1908 ordinance (pushed by Health Commissioner W. A. Evans) required tuberculin testing of cows within city limits, which covered few animals, and the pasteurization requirement was meant to apply only until testing was in place. The ordinance did not define pasteurization. (Wolf, Don't Kill Your Baby, 2001, as summarized by a Slovenian sanitation wiki; weak secondary, opened)
• Historian Alan Czaplicki's abstract says pasteurization had "few outspoken political supporters" in Chicago yet became the main purification strategy, and that eight years passed between its entry into law and full mandatory pasteurization. The full text was paywalled and not read. (Czaplicki 2007)

The reformers and the numbers they cited

• Nathan Straus, a New York merchant and philanthropist, paid for 297 milk stations in 36 cities, per an American Heritage article. The article says Straus was arrested for "adulterating" milk and that milk distributors resisted. It says 6 of 20,111 children fed from his program died over four years, and that Straus's work saved 445,800 children. The article cites no primary source for these figures, and we treat them as claims, not findings.
• The same article says Chicago's voluntary pasteurization "cut the infant death rate in half." We did not verify this.

The federal tally of outbreaks, 1938 to 1951

The Public Health Service's own count (Table 2 of its 1952 summary) of milk and milk-product outbreaks:

The report says milk-borne typhoid epidemics fell from about 12 a year (1938 to 1940) to about one a year (1949 to 1951), and that outbreaks fell by about two-thirds between 1939 to 1941 and 1949 to 1951. In 1951, raw milk was the vehicle in three of four described outbreaks; the fourth involved pasteurized milk likely contaminated afterward. The report notes more localities were requiring pasteurization and the authors believed this helped. It gives no figure for the share of milk pasteurized, and the narrative (four outbreaks, 36 people) does not fully reconcile with the table (12 outbreaks). (Dauer, "1951 Summary: Food and Water Borne Disease Outbreaks," Public Health Reports 67(11), Nov. 1952; opened. A primary agency report.)

Recent outbreaks and legal patchwork

• CDC's study of 1993 to 2006 found 122 dairy-associated outbreaks in 30 states. Of 121 with known pasteurization status, 73 (60%) involved unpasteurized products: 1,571 illnesses, 202 hospitalizations, 2 deaths. The 48 pasteurized-product outbreaks caused 37 hospitalizations and 1 death. Total illnesses across all 121 outbreaks were 4,413. Hospitalization was 13% in nonpasteurized outbreaks versus 1% in pasteurized. Sixty percent of ill people in nonpasteurized outbreaks were under 20. (Langer et al., Emerging Infectious Diseases 18(3), March 2012; opened. A peer-reviewed CDC study.)
• Twenty-one states then allowed in-state sale of unpasteurized dairy products. Of 71 analyzable nonpasteurized outbreaks, 55 occurred in states where such sale was legal (the abstract rounds this to 75%; the text gives 77%). The outbreak-rate ratio for fluid milk was 2.20 (95% CI 1.14 to 4.25) and for cheese 5.70 (1.71 to 19.05); illness-rate ratios were not statistically significant. (Langer et al.)
• The study's "about 150 times" figure for outbreaks per unit consumed rests on a hypothetical assumption that 1% of products are consumed unpasteurized. (Langer et al.)
• A 2025 magazine profile reports raw milk is legal to sell in some form in 43 states. We could not verify this against a state-by-state primary list. (Mother Jones; opened)
• FDA says about one person in every 2 billion servings of pasteurized milk gets sick. (FDA, opened)

Disputed numbers and findings

| Item | Figure A | Figure B | Notes | |---|---|---| | First compulsory pasteurization | Chicago, 1908 (IDFA; American Heritage) | New York City, 1910 (Wikipedia) or 1914 (American Heritage) | Chicago first in two of three sources; New York dates differ | | First state pasteurization law | 1947 (Wikipedia) | Alabama adopts model ordinance 1924 (FDA) | Different things: a state mandate vs a model code | | Nonpasteurized outbreak share in legal states | 75% (Langer abstract) | 77% (Langer text) | Same paper, rounding | | Total outbreaks 1951 | 12 (PHR table) | 4 described (PHR narrative, 36 cases) | Not reconciled | | Straus effects | 6 deaths among 20,111 children (American Heritage) | none independent | Unsourced; treat as claim |

What this case shows

1. A hidden risk became a public rule through local politics. A parent could not see tuberculosis or typhoid in a milk bottle. City councils, health commissioners and reformers such as Nathan Straus put the risk on the public agenda, and Chicago's ordinance (1908) and New York's (1910 or 1914) were local decisions that voters and officials could see and contest. (American Heritage; Czaplicki)
2. The rule came from many hands, not one vote. Czaplicki's finding that the Chicago decision "did not occur at a clearly defined point" shows how a large public choice can be assembled by agencies, courts and interest groups. Ordinary people had little direct say in the details, such as the missing definition of pasteurization in the 1908 text. (Czaplicki abstract; Wolf via wiki)
3. A model ordinance let states copy a tested rule. The 1924 Standard Milk Ordinance, now the Pasteurized Milk Ordinance, gave states a ready text, with FDA and states formalizing the program in 1977. Eventually all states adopted it. That is a form of shared record anyone can read. (FDA)
4. The outcome data are public. Federal outbreak tallies from 1938 to 1951 and CDC's 1993 to 2006 review let any resident compare risk. (Public Health Reports 1952; Langer et al.)
5. Who was left out. The 1908 Chicago law reached only cows inside the city, so milk from outside herds depended on other rules. Poorer families, who bought the cheapest milk, are the ones the reformers say were most exposed, though we did not find a quantified breakdown. Raw milk today is a choice mostly made by adults for children, so the people at risk (60% under 20 in the CDC study) are not the people who decide. (Wolf via wiki; Langer et al.)

The strongest objections, and our answers

1. Objection: Illness fell because of refrigeration, inspection, cleaner water and better living conditions, not pasteurization. Mitigation: We say this plainly. Economists Anderson, Charles, McKelligott and Rees, using city data for 1880 to 1910, found milk inspections against adulteration had small and statistically insignificant effects on infant and child mortality, and a companion study of 25 to 26 cities from 1900 to 1940 found no appreciable effect of bacteriological milk standards or tuberculin-test rules on infant mortality. They suggest home heating of milk, mechanical ice and water purification may have mattered more, but did not test those. Komisarow (2017, as cited in that paper) found dairy farm inspections linked to a 14 to 20% fall in diarrhea and enteritis deaths among one-year-olds. (IZA DP 14975, Dec. 2021; Cato Research Brief 150, 2019; both opened) These studies measure city ordinances in the early 1900s and do not test pasteurization of a defined bottle. The 1938 to 1951 federal count of outbreaks, taken during a period of wider pasteurization, is consistent with a pasteurization effect but also with refrigeration and rising standards. We do not assign shares.
2. Objection: Raw milk advocates say modern raw milk is safe with good farm testing and that choice belongs to consumers. Mitigation: We report their position (raw dairy producer Mark McAfee cites on-farm pathogen testing, and the movement frames the issue as "health freedom"; the Farm-to-Consumer Legal Defense Fund, founded 2007, seeks legal raw sales in every state). We also report the CDC finding that raw products cause far more outbreaks per unit consumed, with the 1% assumption disclosed, and that most raw outbreaks occurred in states where sales were legal. Both sides cite real data and a value difference about risk and freedom remains. (Mother Jones, an advocacy-adjacent magazine profile of the advocates; Langer et al.)
3. Objection: Pasteurization is not a perfect guarantee. Mitigation: Agreed. Pasteurized products caused 48 outbreaks, 37 hospitalizations and 1 death in the CDC 1993 to 2006 count, and a 1951 outbreak involved post-pasteurization contamination. (Langer et al.; PHR 1952)
4. Objection: Mandates raised costs and hurt small dairies. Mitigation: We did not find a verified cost study for early pasteurization requirements. We flag this as an open question. One article notes raw milk selling at almost $9 a gallon, about three times local regular milk, in one Pennsylvania example. (WFAE/NPR, 2020, opened; one anecdote)
5. Objection: Straus-era mortality claims are overstated. Mitigation: We agree they are unsourced in the article we read and do not use them as findings.

Open questions: what would change our minds

• Czaplicki's full text was paywalled. Everything beyond the abstract about the Chicago process is unverified.
• The 1908 Chicago ordinance text was not opened. Claims about its scope (cows in city limits only, no definition of pasteurization) come from a secondary wiki summary of one book.
• The 1910 and 1914 New York dates come from two secondary sources that disagree. A primary city record is needed.
• The 1947 first-state and 1973 federal claims come from Wikipedia only. The 1987 FDA rule was verified in the CFR; the statute behind earlier federal action was not.
• The 1924 Standard Milk Ordinance text and the Alabama adoption were not opened beyond the FDA summary.
• The share of milk pasteurized over time (needed to link the 1938 to 1951 decline to pasteurization) was not found. The 1952 report gives none.
• Costs to dairies and consumers, and any quantified difference by income or race, were not found. Unverified.
• Straus-era mortality figures have no primary source in our reading.
• The "43 states" raw milk legal figure and the "21 states" figure (as of the CDC study) are from different dates and sources, and we did not obtain a current state-by-state primary listing.
• The Anderson et al. studies were read as an IZA discussion paper and a Cato brief of an NBER paper, not the final journal versions. The companion 1900 to 1940 study was not opened directly.
• Would change our minds: city-level data linking pasteurization adoption dates to infant diarrhea deaths; a primary record of Chicago's 1908 vote.

Sources

Found an error or a better source? We keep every correction on the record with its date and reason. Nothing here is quietly rewritten.