Raw Milk Risks from a Microbiologist’s Perspective

By Peg Coleman, MS

The late Dr. Theodore (Ted) Fairbank Beals, MD, made significant contributions to bringing more science into dialogues about raw milk benefits and risks.

Dr. Beals was instrumental in obtaining data through the Freedom of Information Act (FOIA) from U.S. states that monitor microbes in raw milk from farms licensed at the state level. Dr. Beals introduced these FOIA data to readers of this journal before his death last year in 2021.¹

My collaborators and I share the belief articulated by Dr. Beals that policies without a sound basis in scientific evidence cannot promote health and well-being in the populations subject to those policies. Yet, policies around pasteurizing raw milk, both human donor breastmilk and milk from ruminants, are not based on 21st-century scientific evidence. This article will introduce readers to highlights from the FOIA data project report and provide information about its application in Microbial Risk Assessment (MRA) (See below).

HIGHLIGHTS OF THE FOIA DATA AND EXPOSURE ASSESSMENT

The objective of our project was to summarize the data from routine testing for microbial pathogens in fresh unprocessed milk from licensed farms obtained by FOIA through Dr. Beals as mentioned above. Results from the Microsoft Access database project are summarized in Table 1 below.²

A more extensive table on pathogen testing results for raw milk was developed from multiple documents, which summarized the data from FOIA as well as data from multiple countries (Canada, Finland, Germany, Poland, U.S., and U.K.). The overall results are shown in Table 2 below.³ Note that pathogens were detected in 0.01 percent or fewer of all samples.

Although just knowing data on the occurrence (frequency or rates of pathogen positives) in foods is insufficient to estimate risk, it is reasonable to ask how a food with such extensive recent data from around the world documenting that more than 99 percent of routine samples were undetectable for major foodborne pathogens is an “inherently dangerous food.” From my experience, experts with pro-pasteurization biases provide no recent evidence or analysis that supports this opinion.

TABLE 1. Results Reported under FOIA on Detection of the Presence of Major Microbial Pathogens in Raw Milk from Licensed Dairy Farms in Four State Sampling Plans.²

TABLE 2. Recent Results on Pathogen-Positive Rates in Raw Milk Reported in Peer-Reviewed Studies and Recent FOIA Data.³

MICROBIAL RISK ASSESSMENT

Microbial or Microbiological Risk Assessment (MRA) is a rigorous interdisciplinary process organized around a consensus framework ratified in 1999 by the one hundred sixty-three member countries of the Codex Alimentarius Commission.^11,20 MRAs may apply qualitative methods and report categories of risk levels (such as negligible, low, moderate, high risk) or quantitative methods (QMRAs) and report risk estimates per year or per serving.

Foodborne risk is estimated by conducting a series of discrete and interconnected technical analyses illustrated in Figure 1.²¹ These involve:

• Hazard Identification
• Exposure Assessment
• Dose-Response Assessment
• Risk Characterization

This article emphasizes Exposure Assessment because the data received through the Freedom of Information Act (FOIA)1 and the growth study are useful for estimating and assessing the likelihood and magnitude of pathogen exposures to consumers in servings of contaminated foods.

It’s important to understand one basic principle of Dose-Response Assessment: as the number of pathogens ingested increases, the frequency (likelihood) and severity of illness increases. “Low levels equal low risk.”²²

Some key general principles of the eleven listed in the 1999 consensus document on principles and guidelines for Microbiological (Microbial) Risk Assessment11 are as follows:

1=Microbiological Risk Assessment should be soundly based upon science.
5=The conduct of a Microbiological Risk Assessment should be transparent.
11=A Microbiological Risk Assessment may need reevaluation, as new relevant information becomes available.

GROWTH AND SURVIVAL OF PATHOGENS

Regarding growth and survival of pathogens for exposure assessment, analysts may select growth models that intentionally over-estimate risk, such as using data for optimal growth of pathogens in pure culture broth.

However, a recent pilot study conducted by a certified laboratory4 and funded by the Raw Milk Institute (RAWMI) documented the inability of the major bacterial pathogens to grow in raw milk for a week of storage at the temperature that U.S. regulatory agencies recommend for refrigerated foods: 4.4 °C (40°F).⁵

20TH vs 21ST-CENTURY SCIENCE

Many 21st-century studies of the microbiota of milk^3,6 are inconsistent with beliefs based on 20th century science. Certainly, 20th-century science, opinions and beliefs selected by Food Standards Australia New Zealand (FSANZ)7 in 2009 swayed the Toronto judge in the recent decision maintaining Canada’s prohibition on access to raw milk.⁸ The judge apparently believed the pro-pasteurization argument that milk should be sterile and the microbes present are the result of fecal contamination.

Apparently, the Toronto judge relied on an outdated quantitative method whose models simulated not data from sound scientific studies, but a series of worst-case assumptions, extrapolations and opinions that intentionally overestimated risk and underestimated uncertainty. Further, the judge and others mistakenly assumed that evidence from outbreaks was sufficient to estimate risk, while evidence from predictive microbiology was excluded, dismissed or ignored.

Contrary to FSANZ’s view, pathogens in feces are not predictive of pathogen presence or levels in raw milk. My recommendations to FSANZ from a technical review⁹ included abandoning its outdated views on fecal contamination for raw milk and conducting a reassessment of their 2009 simulations using recent evidence for benefits and risks.

I am not the only scientist to question the assumptions and outputs of the 2009 FSANZ simulations. The European Food Safety Authority (EFSA)¹⁰ also considered the FSANZ 2009 report and peer-reviewed publications on more recent risk assessments for raw milk. EFSA concluded that risks for raw milk consumers can be mitigated and reduced significantly by controlling temperature, limiting shelf life and engaging consumer compliance with controls (that is, maintaining proper refrigeration temperatures for raw milk).

Further, EFSA concluded that many potential pathogens are not main hazards to consumers in the European Union including Listeria monocytogenes and Staphylococcus aureus.

Those familiar with New York state regulations for raw milk monitoring may be puzzled about the EFSA determination that these two pathogens are not considered main hazards to raw milk consumers. In fact, farmers who pay the licensing fee in New York state are paying for routine testing for two pathogens never linked to an outbreak associated with raw milk in the state, based on data obtained from the Centers for Disease Control (CDC).

The FSANZ modeled or simulated potential risk based on a series of intentionally conservative (biased) assumptions and indirect or extrapolated data that have not been validated then or since. FSANZ seems to have selected assumptions, opinions and extrapolations that exaggerated risks and underestimated uncertainties, consistent with their pre-conceived pro-pasteurization bias articulated throughout the report.

The FSANZ simulations were not soundly based on science, nor were alternative assumptions tested to increase transparency. In short, FSANZ did not comply with principles and guidelines stipulated from international consensus.¹¹ My peer review of the FSANZ report,⁹ undertaken twelve years after its release, identified many relevant studies available before release of the report that were intentionally or inadvertently excluded by FSANZ. I strongly recommended that FSANZ update the assessment and incorporate scientific data from technological advances of the last decade to improve the credibility of the assessment.⁹

Fear and dread of many (or all) microbes as “germs” that will kill us (germophobia) appear to factor strongly into policies requiring pasteurization and regulations on the presence of potential pathogens, not their levels or their risk for causing illness. The fear of microbes as “germs” appears to be entrenched even among well-meaning scientists and regulators in misconceptions of 20th-century science, and wall them off from any consideration of the tremendous advances in knowledge about the microbiota of milk, particularly the rich body of evidence for both benefits and risks of raw milk from both humans6 and cows.³ At present, the pasteurization and zero-tolerance policies for potential pathogens in raw milk appear inconsistent with the available evidence and the state of the science in the 21st century.

FUTURE FOR EVIDENCE-BASED POLICIES ON RAW AND PASTEURIZED MILK

Readers of Wise Traditions may be aware that many factors influence what is published and what is rejected about science and its applications in risk assessment. According to a recent report by the National Science and Technology Council,¹² novel scientific discoveries that challenge established dogmas may be suppressed, manipulated and inappropriately influenced by political pressures and interference to distort outcomes to maintain the status quo or meet preferred policy objectives or decisions. To quote from this report, scientific integrity can be impeded by “mischaracterizing, fabricating, removing, or disregarding relevant scientific information.” Undoubtedly, there is great need for developing or improving evidence-based decisions guided by the best available science and data, recognizing that scientific and technological information and data are central to the development and iterative improvement of sound policies. The report further describes political interference as “inappropriate, scientifically unjustified intervention in the conduct, management, communication, or use of science.”

Just as scientists are not unbiased or immune to economic, political and social pressures, neither are editors and reviewers for scientific journals. A recent New York Times article by Gina Kolata and Benjamin Mueller13 mentioned an innovative scientific paper “summarily rejected” by two prestigious journals (Nature and Science) before its eventual acceptance in a “niche publication called Immunity.” Similarly, our work on bovine milk was rejected by two scientific journals before acceptance by the Open Access journal Applied Microbiology. Certainly, my co-authors and I improved the publication and its communication of the evidence map work in responding to reviewers in three separate peer-review processes. However, I have no doubt that pro-pasteurization biases delayed publication of a comprehensive and simultaneous analysis of benefits and risks for raw milk for more than two years.

If you followed the Toronto case involving raw milk farmer Michael Schmidt, you may have realized that the U.S. government is on record for attempting to interfere with an independent scientific journal that published the 2018 Whitehead and Lake analysis of CDC data on raw and pasteurized milk outbreaks (see Table 3).¹⁴ The U.S. government expert (Mr. John Sheehan, FDA) testified that U.S. government analysts were working to repeat both the Whitehead and Lake analysis (2018) and a subsequent analysis of the same data by statistician Dr. Nick Azzolina¹⁵ who submitted an affidavit with his analysis of the same CDC dataset. The important point is that for the years 2005-2017, the CDC recorded more illnesses from campylobacter and listeria in pasteurized milk compared to raw. I am collaborating with Nick Azzolina, Joanne Whitehead, Bryony Lake and Michele Stephenson to extend the analysis for more recent outbreak data from the CDC for 2005 to 2019.

In cross-examination, Toronto attorney Ian Blue asked the government official whether the results of their reanalyses would be published if consistent with prior analyses. To date, I am aware of no subsequent publication that either refutes or confirms the findings of Whitehead and Lake or Azzolina. Yet the Toronto judge appears to have succumbed to blatant political intrusion and aligned her decision with the unsupported opinions of the government official over independent statistical analysis of U.S. outbreaks by an accomplished statistician.

Clearly, processes for scientific peer review are subject to political and other pressures. Yet, peer-reviewed studies are crucial to providing credible evidence about raw milk benefits and risks to courts, legislatures and regulatory agencies around the world. Even when some opinions and claims are made that pasteurization is a silver bullet that decreases risk and increases benefits to consumers, peer-reviewed studies with robust statistical analysis are crucial to helping judges, legislators and regulators to properly acknowledge and weigh the evidence.

TABLE 3. CDC Outbreak Data for Two Pathogens.¹⁴

RECOMMENDED DAILY ALLOWANCES FOR MICROBES?

A question that may be of interest to WAPF members concerns the concept of expanding Recommended Daily Allowances (RDAs) for vitamins to RDAs for microbes.^16,17 These studies were the subject of my Society for Risk Analysis webinar last year entitled “Resilience and the Human Superorganism: Give Us this Day Our Daily Microbes.”¹⁸ Foods naturally enriched in microbes, including raw milk¹⁹ and fermented foods (such as cheese, kefir, kimchi and kombucha), certainly could contribute to RDAs for microbes.

I strongly believe that questions from raw milk stakeholders are essential for consideration of the evidence (or lack thereof) behind pasteurization policies and monitoring requirements for farms licensed to sell raw milk. Consumers deserve to have a voice in decisions about pasteurizing donor breastmilk and cow milk, particularly to maintain and extend freedom of choice to consumers around the world.

In summary, recent research on the benefits and risks of raw milk³ does not support the outdated assumptions that raw milk is inherently dangerous, and that existing hygiene management programs, including Hazard Analysis and Critical Control Points, and Test-and-Hold Programs, cannot ensure a safe, low-risk product for raw milk consumers.

This article was first published in the Spring 2023 issue of Wise Traditions in Food, Farming, and the Healing Arts, the quarterly journal of the Weston A. Price Foundation.

ABOUT THE AUTHOR

Peg Coleman, MS, is a medical microbiologist, a microbial risk assessor and a fellow of the Society for Risk Analysis (SRA). Her long career as a microbial risk assessor began with the U.S. federal government (USDA/FSIS) and continues as a consultant. Her primary interests are benefit-risk analysis and resilience of human superorganisms, Homo sapiens complete with microbial partners in health.

ACKNOWLEDGMENTS

I am deeply grateful for contributions from WAPF, the Raw Milk Institute (RAWMI) and others through a 2018 crowdfunding campaign (Whole Truth, Whole Milk) through the Society for Risk Analysis (SRA) that provided partial support for preparing the two evidence map publications.^3,6 I appreciate ongoing support from Mark McAfee of RAWMI and Sally Fallon Morell of WAPF. I strongly value the opportunity to serve on the advisory board of RAWMI. I acknowledge support from Mark McAfee of RAWMI and Abby Rockefeller of Churchtown Dairy on the pathogen growth study project.

REFERENCES

1. Beals T. Observations on the collection of fresh unprocessed milk samples from states regulating dairies: There are two kinds of milk. Wise Traditions. Summer 2021;22(2):97-100. https://www.westonaprice.org/wp-content/uploads/Summer2021.pdf
2. Stephenson M, Coleman ME. Final report: Database of primary microbial testing program data for raw milk stored in Microsoft Access®. Coleman Scientific Consulting, Aug. 27, 2021. Available at https://www.realmilk.com/database-of-primarymicrobial-testing-program-data-for-raw-milk-storedin-microsoft-access/.
3. Dietert RR, Coleman ME, North DW, Stephenson MM. Nourishing the human holobiont to reduce the risk of non-communicable diseases: A cow’s milk evidence map example. Appl Microbiol. 2022;2(1):25-52.
4. Brandt AL. Determination of Growth Rate of Salmonella enterica spp., E. coli O157:H7, Campylobacter spp., and Listeria monocytogenes in Raw Milk. Food Safety Net Services, Mar. 15, 2022. Available for download at https://www.rawmilkinstitute.org/updates/pathogen-growth-in-raw-milk?rq=determination%20of%20growth%20rate%20of%20salmonella.
5. Smith S. How well do pathogens grow in raw milk? Raw Milk Institute, Mar. 16, 2022.
6. Coleman ME, North DW, Dietert RR, Stephenson MM. (Examining evidence of benefits and risks for pasteurizing donor breastmilk. Appl Microbiol. 2021;1(3):408-425.
7. Food Standards Australia New Zealand. Microbiological Risk Assessment of Raw Cow Milk. Risk Assessment Microbiology Section, Dec. 2009. https://www.foodstandards.gov.au/code/proposals/documents/P1007%20PPPS%20for%20raw%20milk%201AR%20SD1%20Cow%20milk%20Risk%20Assessment.pdf
8. Affleck v. The Attorney General of Ontario, 2021 ONSC 1108 (CanLII). https://www.canlii.org/en/on/onsc/doc/2021/2021onsc1108/2021onsc1108.html
9. Coleman ME. Improving the Credibility of the Food Standards Australia New Zealand Report Entitled Microbiological Risk Assessment of Raw Cow Milk (2009) Considering New Evidence. Report submitted to Australian Raw Milk Movement, July 26, 2021. Available at https://www.ausrawmilk.org/.
10. European Food Safety Authority (EFSA) Panel on Biological Hazards. Scientific opinion on the public health risks related to the consumption of raw drinking milk. EFSA Journal. 2015;13(1):3940.
11. Codex Alimentarius Commission (CAC). Principles and Guidelines for the Conduct of Microbiological Risk Assessment. 1999. Accessed Mar. 8, 2021 at https://www.fao.org/3/y1579e/y1579e05.htm.
12. National Science and Technology Council. Protecting the Integrity of Government Science. Scientific Integrity Fast-Track Action Committee, Jan. 2022. https://www.whitehouse.gov/wp-content/uploads/2022/01/01-22-Protecting_the_Integrity_of_Government_Science.pdf
13. Kolata G, Mueller B. Halting progress and happy accidents: how mRNA vaccines were made. The New York Times, Jan. 15, 2022.
14. Whitehead J, Lake B. Recent trends in unpasteurized fluid milk outbreaks, legalization, and consumption in the United States. PLoS Curr. 2018;10:ecurrents.outbreaks.bae5a0fd685616839c9cf857792730d1.
15. Azzolina NA. Summary Report: Statistical Analysis of Raw Milk-Related Outbreaks, 2005-2016, 2019, as reported in Supplemental Table 1 from Whitehead and Lake, 2018. Analysis funded by RAWMI and submitted subsequently as an affidavit for the Toronto case.
16. Hill C. RDA for microbes—are you getting your daily dose? Biochem (Lond).2018;40(4):22-25.
17. Marco ML, Hill C, Hutkins R, et al. Should there be a recommended daily intake of microbes? J Nutr. 2020;150(12):3061-3067.
18. Society for Risk Analysis. Resilience and the human superorganism: Give us this day our daily microbes. June 2, 2021. https://www.sra.org/webinar/resilience-andthe-human-superorganism-give-us-this-day-our-daily-microbes/
19. Oikonomou G, Addis MF, Chassard C, et al. Milk microbiota: What are we exactly talking about? Front Microbiol. 2020;11:60.
20. LeJeune JT, Zhou K, Kopko C, Igarashi H. FAO/WHO joint expert meeting on microbiological risk assessment (JEMRA): Twenty years of international microbiological risk assessment. Foods. 2021;10(8):1873.
21. Coleman ME, Dietert RR, North DW, Stephenson MM. (2021). Enhancing human superorganism ecosystem resilience by holistically “managing our microbes.” Appl Microbiol. 2021;1(3)471-497.
22. Chen Y, Ross WH, Scott VN, Gombas DE. Listeria monocytogenes: low levels equal low risk. J Food Prot. 2003;66(4):570-577.