Over the years, the meat industry has faced substantial challenges in food safety. From E. coli O157:H7 in the 1990s associated with ground beef to Listeria in ready-to-eat meats and the Salmonella challenges with poultry, the industry has had its fair share of outbreaks. Fortunately, scientists and the industry have stepped up in order to mitigate pathogens and improve public health. While all illnesses haven’t been eliminated, we have made substantial strides in reducing them. Outbreaks associated with produce came on the scene later than major ones in meat, and the leafy green industry continues to be plagued with pathogens.

I began my career studying pre-harvest food safety and developing strategies to monitor and/or control pathogens in beef cattle. I continued on this path for several years until the funding was gone and, thankfully, STECs were under control in ground beef. However, this area is emerging again as a hot topic. In June, the FDA released the results of a longitudinal microbiological study conducted in Arizona evaluating the environmental impact on contamination of leafy greens. More data on the study were presented last week at the International Association for Food Protection meetings. The report can be found at this link. Generally, environmental samples were taken in areas surrounding crops. The study reports that STEC were recovered in air samples and suggest that a nearby CAFO operation contributed to the pathogens in the air. They also found positive water and wildlife fecal samples in the study. More than 40 different STECs were identified through WGS in 500 samples.

NCBA responded to this study and emphasized some key points and data gaps. First of all, the STEC strains were not isolated from the nearby cattle operation. Additionally, no routes of contamination were identified in this study. The longitudinal study was conducted in response to a major outbreak that occurred in 2018 to better understand routes of contamination. However, in the end, we are still left with assumptions and not hard evidence. FDA outbreak reports about leafy green-associated illnesses as well as this study “suggest” that cattle are responsible for contamination, even though there is no direct evidence.

Last year, our team published a paper, “Understanding potential cattle contribution to leafy green outbreaks: A scoping review of the literature and public health reports”. In this scoping review we analyzed every study investigation from the FDA as well as scientific studies and found no direct evidence that livestock were contaminating the leafy greens in these reports. The terms “assumed,” “potential” and “suspected” were common, but nothing was confirmed. I agree that there is “potential,” but without direct evidence or routes of contamination, little action can be taken. Additionally, there is a big danger in finger pointing because without direct, empirical evidence, we can’t form a strategy to prevent future outbreaks. Also, focusing on one source only can lead an investigation team to the wrong source or can even focus on research into the wrong areas.

What are the next steps that can result in impactful change? FDA has published the Leafy Green Action Plan with “suggestions,” but there are tremendous data gaps in this document. It is critical to have a better understanding of the issues. I have been engaged in One Health discussions with the leafy green and livestock industries in collaboration with the FDA, USDA, AFDO and CDC and we are working to identify data gaps. Our next steps are to assemble a think tank of scientists from across the industries with representation from commodity groups to solve this problem. We are championing for a data-driven and science-based approach to identify routes of contamination and all potential sources of the pathogen.

Speculation and assumptions get us nowhere, but science and data can reveal the gaps and progress can be made. We have seen it happen in the past and can make a difference. Our industry has set a road map and I hope the produce industry can follow.

Crossing commodities

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