Much of the romaine lettuce grown in the Yuma, AZ, area comes from fields adjacent to or very near feedlots. These fields were still flush with fresh produce before and during the 2018 outbreak. Many growers irrigate leafy greens and other produce in the area with water from some of the hundreds of miles of open canals, some of which run alongside animal feeding operations such the one shown in the background here.

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In response to FDA’s “Southwest Agricultural Region Environmental Microbiology Study (2019 – 2024)” the National Cattlemen’s Beef Association wrote, “Clearly, more scientific data is needed…” (1) . I disagree, there is a plethora of scientific data in the FDA study plus the considerable body of scientific data published in the past two decades. Those data demonstrate that the carriage of enteric zoonotic pathogens by cattle swine and poultry is an environmental and public health hazard. More delay means more illnesses, costs, and deaths. 
*https://www.fda.gov/food/environmental-studies/southwest-agricultural-region-environmental-microbiology-study-2019-2024

A recent review (2) also concluded more research is needed. The authors wrote, “Although the collected information regarding the proximity of cattle is a concern, data gaps indicate that more studies should be conducted to determine the relative contribution of different mechanisms of contamination and generate quantitative data to inform food safety risk analyses, regarding leafy greens produced nearby livestock areas.” This and the Cattlemen’s statement is a classic example of rather than make a decision on current information, “Let’s wait until we have more information, and more, …”.

There are interventions for runoff from CAFOs (3) but they don’t inhibit airborne and other vectors (4). For more information read the references in (4), copy the title into Google Scholar, and peruse the 104 scientific articles that cite it or just the seven this year. 

The scientific publications demonstrate that fecal borne zoonoses contaminate the environment via manure, air, water, and feral animals. In addition to the environment, FSIS wrote that it was unable to eliminate the pathogens entering establishments on pork. Science shows that the enteric pathogen hazard on beef and poultry is similar. For example in beef processing, the dust from hides (dried feces) is a primary source of enteric pathogens (5). “Hide has been established as the main source of carcass contamination during cattle processing; therefore, it is crucial to minimize the amount of Escherichia coli O157:H7 on cattle hides before slaughter.” While walking through a beef slaughter establishment, look up at a light or window and you will see an aerosol of dust. Washing hides before pulling them reduces that hazard. There is still the hazard of fecal contamination from dropping the bung (that has improved over the past three decades), the Salmonella in lymph nodes and the STEC coming from the buccal cavity. Thus, the slaughter interventions are similar to slapping mosquitoes and ignoring their source, stagnant water.

Beef is the easy product to solve. The mechanical defeathering and dehairing processes for poultry and swine spread “Non-visible fecal material” over the carcasses and into empty follicles wher interventions cannot reach (6)(7). 

Another paper promoting the need for preharvest interventions, “The purpose of this paper is to propose a more integrated and more aggressive system approach to food safety rather than focusing on one segment of the industry, or on one approach as described by or constrained by one set of regulations. We focus on the prevalence and control measures for Salmonella and Escherichia coli, particularly, Shiga toxin-producing E. coli (STEC) in live cattle on the farm and in the final raw beef product at retail…” and “Little emphasis is put on the conditions on the farm or at the feedyard wher pathogen control can begin.” (8)

The research and reviews on preharvest interventions are numerous. What is lacking are incentives and regulation to provide a level playing field. CDC, EPA, FDA, or FSIS cannot sample CAFOs to determine the source of zoonoses. APHIS can sample but it can only act on animal pathogens not human pathogens (remember egg inspection?). Congress should act to enable sampling of CAFOs, including beef, poultry, and swine production operations. 
Tracing a zoonotic pathogen to it’s source will then enable regulatory action to prevent or reduce the public health hazard and protect operators implementing interventions from an economic disadvantage.

1. Cattlemen contest research that shows dust from feedlots can contaminate irrigation water
By Coral Beach on June 16, 2024
https://www.foodsafetynews.com/2024/06/cattlemen-contest-research-that-shows-dust-from-feedlots-can-contaminate-irrigation-water/

2. Dogan, O.B., Flach, M.G., Miller, M.F. and Brashears, M.M., 2023. Understanding potential cattle contribution to leafy green outbreaks: A scoping review of the literature and public health reports. Comprehensive Reviews in Food Science and Food Safety, 22:3506-3530

3. Glaize, A., Young, M., Harden, L., Gutierrez-Rodriguez, E. and Thakur, S. 2021. The effect of vegetation barriers at reducing the transmission of Salmonella and Escherichia coli from animal operations to fresh produce. International J Food Microbiol. 347:109196. 

4. Berry, E.D., Wells, J.E., Bono, J.L., Woodbury, B.L., Kalchayanand, N., Norman, K.N., Suslow, T.V., López-Velasco, G. and Millner, P.D., 2015. Effect of proximity to a cattle feedlot on Escherichia coli O157: H7 contamination of leafy greens and evaluation of the potential for airborne transmission. Appl. Environ. Microbiol. 81:1101-1110.

5. Arthur, T.M., Bosilevac, J.M., Brichta-Harhay, D.M., Guerini, M.N., Kalchayanand, N., Shackelford, S.D., Wheeler, T.L. and Koohmaraie, M., 2007. Transportation and lairage environment effects on prevalence, numbers, and diversity of Escherichia coli O157: H7 on hides and carcasses of beef cattle at processing. Journal of Food Protection, 70:280-286.

7. Zeng, H., Rasschaert, G., De Zutter, L., Mattheus, W., & De Reu, K. (2021). Identification of the Source for Salmonella Contamination of Carcasses in a Large Pig Slaughterhouse. Pathogens, 10:77.

7. Berrang, M. E., Meinersmann, R. J., & Adams, E. S. 2018. Shredded sponge or paper as a cloacal plug to limit broiler carcass Campylobacter contamination during automated defeathering. Journal of Applied Poultry Research, 27:483-487.
8. Brashears, M.M., Chaves B.D.. 2017, The diversity of beef safety: A global reason to strengthen our current systems. Meat Science 132: 59-71.