A new in-depth study of raw milk illnesses in the U.S. by a university researcher concludes that “the outbreak rate has effectively decreased by 74% since 2005.” 

The 38-page study, which includes 138 footnotes and was published in the refereed PLOS Current Outbreaks, also concludes that the risk of illnesses has actually declined in the face of increased consumption: “The potential for foodborne illness continues to be a small but real risk from consuming unpasteurized fluid milk, but analysis of data over a twelve year period demonstrates that increased access to this product within the United States has not led to increased outbreak rates. On the contrary, total reported unpasteurized milk-associated outbreaks have declined since 2011, despite increased production, and outbreak rates proportional to estimated consumption rates have declined by 74% over the twelve year period.”  

The study’s authors—Joanne Whitehead, a researcher at the University of Victoria in Canada; and Bryony Lake, a professional researcher and policy analyst in Canada— suggest broader implications beyond providing insights into the long-running debate over raw milk safety by arguing that “given the potential for significant public health benefits which could be gained from a reduction in immunological disorders, a re-evaluation of the risk/benefit profile of unpasteurized milk is in order.” 

This new study is significantly at odds with two studies from the U.S. Centers for Disease Control, which conclude that risk from raw milk is much more serious than from pasteurized milk, and that the risk is rising. 

The new study allows that data used to analyze dairy safety, no matter who is doing the assessment, is incomplete and even confusing because of varying reporting by states and because of the highly variable legal situation with regard to raw milk among the states. The authors clearly explain in the study their challenges in obtaining and evaluating data from individual states about such matters as the number of new raw dairy permits issued and the number of illnesses recorded. Among their specific research findings: 

  • Beginning in 2005, the trend for several years was of rising illness rates, followed by a declining rate, as shown in the graphic at the top of this post. “Excluding data for 2009 (indications of a data integrity problem), annual reported outbreaks related to unpasteurized fluid milk started at a low of 10 in both 2005 and 2006 and rose to peak at 18 in both 2010 and 2011. After this peak, outbreaks then saw a general decrease: 14 in 2012, 16 in 2013 and 2014, 11 in 2015, and 13 in 2016. This results in an annual average of 14 outbreaks for the most recent 5 year span, from 2012 to 2016 inclusive.” 
  • Fears that broadening legalization of raw milk would lead to higher illness rates appear unfounded. “To further examine the hypothesis that legalization leads to higher outbreak rates, one can examine whether a change in legal status within a specific jurisdiction affects the outbreak rate within that jurisdiction……There was no change in absolute number of outbreaks (6 outbreaks in each 4 year period) and a slight reduction in relative outbreak rates due to population growth during this time.” 
  • Safety education makes a difference in reducing raw milk illnesses. “Regarding education, a challenge for dairies has been a lack of on-farm food safety programs. This changed in 2010 when the Farm-to-Consumer Legal Defense Fund made training materials available and the Raw Milk Institute began developing a HACCP-based on-farm food safety program. The decline in frequency of outbreaks coincides with the introduction of these targeted education programs. The tentative conclusion can be drawn that, similar to what was seen in the meat processing industry, the implementation of on-farm food safety systems for unpasteurized milk production may be related to the observed reduction in outbreak rates. Data from Pennsylvania supports this connection….outbreaks occurred each year from 2006 to 2014, then no outbreaks were reported for 2015 or 2016, then one outbreak occurred in 2017. An interesting correlation is that in November 2014, Pennsylvania State University’s College of Agricultural Sciences hosted a workshop on unpasteurized milk safety in collaboration with the Raw Milk Institute. In addition, in 2014 the proprietor of the largest Pennsylvania unpasteurized milk farm was trained and listed with the Raw Milk Institute. This farm had been responsible for outbreaks in 2012 and 2013 (CDCIDs 15533 and 15482) including one associated with 148 out of 258 (57%) unpasteurized milk related illnesses reported nationwide in 2012. No outbreaks have been associated with this farm’s products since training and listing. While it is impossible to show causation, this correlation of fewer outbreaks with the implementation of a HACCP-based on-farm food safety training program has implications for further studies of the role which education and extension programs may play in the safe production and handling of unpasteurized milk.”
  • Raw milk production continues to increase. “It is apparent from licensing statistics and consumer websites that unpasteurized milk is currently being produced on a larger scale than in past decades…. Compiling license and permit numbers for (just) nine states shows an increase over twelve years from 76 to 347 licensed unpasteurized milk dairies (+357%). Assuming that license and permit numbers are a reasonable proxy for consumption, and factoring in U.S. population growth (9.3% over the twelve year period), the ratio between outbreak rate and consumption rate shows a pronounced decline, with the 2016 outbreak-to-consumption ratio only 26% that of 2005.”
  • The U.S. might want to consider having the federal government regulate raw milk, to gain more consistency around the country. “The federal ban on interstate trade  in unpasteurized fluid milk has not eliminated either multi-state outbreaks or the emergence of unregulated interstate buying clubs. As 43 states representing 92.6% of the U.S. population currently (March 2018) permit legal access to unpasteurized milk, and legalization does not correlate with increased outbreak rates, expanded legalization along with the development of a federal regulatory framework could be considered, similar to national systems already in effect in other nations such as England, France, Germany, and New Zealand.”  

This is an impressive study—impressive in significant measure because it takes on this complicated subject, with all its inconsistencies and nuances, and covers it much more adroitly than any of the CDC assessments. The only area not covered, raw milk opponents might argue, is a breakout of the kinds of illnesses that are occurring from tainted raw milk. The CDC and others have argued that there a growing percentage of the raw milk illnesses that are occurring are from E.coliO157:H7, which can lead to complications in children. 

That may be a topic for a follow-on study, because failure to agree on the overall scope of the problem at hand invariably leads to confused, and confusing, arguments. Hopefully this study will lead to some meeting of the minds on where we’ve been and where we are heading in terms of raw milk risk. The signs, from a public health perspective, look much more positive than we’ve been lead to believe.