Leafy greens investigation report 

The FDA has released a report summarizing its investigation into the Fall 2020 outbreak of E. coli O157:H7 illnesses linked to the consumption of leafy greens. The outbreak was linked via whole genome sequencing (WGS) and geography to outbreaks traced back to the California growing region in the fall of 2019 and 2018 that also were associated with the consumption of leafy greens. In the report, the FDA identifies three key findings among the past outbreaks: a recurring outbreak strain, a recurring growing region, and recurring concerns with the potential impacts of adjacent lands. In addition to other potential contributing factors identified, the E. coli O157:H7 outbreak strain was identified in a cattle feces composite sample taken approximately 1.3 miles upslope from a produce farm with fields tied to the outbreaks. As a result of its investigation, the FDA’s leading hypothesis is that cattle are most likely the sources of the outbreak strains of E. coli O157:H7 associated with the 2019 and 2020 leafy greens outbreaks. Accordingly, the report states that “Growers should be aware of and consider adjacent land use practices, especially as it relates to the presence of livestock, and the interface between farmland, rangeland, and other agricultural areas, and conduct appropriate risk assessments and implement risk mitigation strategies, where appropriate.”

In the report, the FDA states that due to the recurring nature of the pathogenic strain of E. coli O157:H7 identified, the persistence of the strain “appears to be a reasonably foreseeable hazard in this area.” The agency also reiterates that farms covered by the Produce Safety Rule are required to implement science- and risk-based preventive measures under the rule, including practices to prevent the introduction of known or reasonably foreseeable hazards into or onto produce. Accordingly, the FDA recommends that the agricultural community in the south Monterey County area of the Salinas Valley and Santa Maria Valley growing regions work to identify where the recurring strain of pathogenic E. coli is persisting and the likely routes to contamination of leafy greens with Shiga-toxin producing E. Coli (STECs).  

The report includes recommendations for both leafy green growers in the California Central Coast Growing Region, as well as all producers of leafy greens.  FDA recommends that growers of leafy greens in the California Central Coast Growing Region do the following:

• Consider the recurring strain of E. coli O157:H7 a reasonably foreseeable hazard. Under the Produce Safety Rule (21 C.F.R. §§ 112.112 and 112.113), farms must: 
  • take all measures reasonably necessary to identify, and not harvest, covered produce that is reasonably likely to be contaminated with a known or reasonably foreseeable hazard; and 
  • handle harvested covered produce during covered activities in a manner that protects against contamination with known or reasonably foreseeable hazards;
• When pathogens are identified through microbiological surveys, pre-harvest, or post-harvest testing of leafy greens, implement industry-led root cause analyses to determine how the contamination likely occurred and then implement appropriate prevention and verification measures; 
• Actively engage in the California Agricultural Neighbors (CAN) workgroup led by the California Department of Food and Agriculture (CDFA) and Monterey County Farm Bureau to identify what actions can be taken to reduce the risk of STEC contamination of leafy greens in this specific growing region; 
• Actively seek participation in the California Longitudinal Study (CALS) to better understand the ecology of human pathogens in the growing region; and
• Actively encourage participation by adjacent and nearby livestock owners and other agricultural producers in the region to participate in CALS as well. 

In light of its findings, FDA also recommends that all producers of leafy greens take the following actions:

• Be aware of and consider risk that may be posed by adjacent land use, especially as it relates to the presence of livestock and the interface between farmland, rangeland, and other agricultural areas; 
• Emphasize efforts around prevention by assessing growing operations to ensure implementation of appropriate science- and risk-based preventive measures, including applicable provisions of the Produce Safety Rule and good agricultural practices. 
• Improve traceability by increasing digitization, interoperability, and standardization of traceability records along the entire leafy green farm to store continuum, which would expedite traceback and prevent further illnesses. The FDA states this measure is important at not only the grower level, but also for shippers, manufacturers, and retailers to improve overall traceability throughout the supply chain; 
• Improve industry-led provenance labeling, including considering adoption of improved (with more detailed specificity beyond the current region designations) and expanded (to leafy greens products beyond just romaine lettuce) labeling to further protect consumers in the event of a product recall and minimize the amount of discarded product; and
• Conduct a root cause analysis when a foodborne pathogen is identified in the growing environment, in agricultural inputs (e.g., agricultural water or soil amendments), in raw agricultural commodities, or in fresh-cut ready-to-eat produce to identify how this contamination occurred.

Updated leafy greens action plan

The FDA also has released an updated version of its Leafy Green Shiga-Toxin Producing E. coli (STEC) Action Plan to reflect the work the agency accomplished in 2020 and its focus areas for the upcoming year. The FDA first released the Action Plan in March 2020 to support an integrated food safety system and help foster coordination between the FDA and public and private stakeholders. The agency’s work over the past year led to the identification of additional steps to help further advance the safety of leafy greens. The updated Action Plan includes a significant number of new planned activities, many of which are in the areas of livestock and adjacent and nearby land use. Other additional action items address: agricultural water safety; traceability throughout the food supply chain; new sampling assignments of romaine in Arizona and California; and biological soil amendments of animal origin, including sampling of compost and biological soil amendments of animal origin.  

Next steps    

The FDA’s investigation report and updated Action Plan signal the agency’s continued focus on the safety of leafy greens and a renewed emphasis on the importance of implementing measures to reduce the potential for E. coli contamination. We will continue to monitor issues related to the safety of leafy greens  and keep you apprised of any developments.  

References

1    Factors Potentially Contributing to the Contamination of Leafy Greens Implicated in the Fall 2020 Outbreak of E. coli O157:H7 (Apr. 2021), available at https://www.fda.gov/media/147349/download.

2    Leafy Greens STEC Action Plan (6 Apr. 2021), available at https://www.fda.gov/food/foodborne-pathogens/leafy-greens-stec-action-plan.