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Controlled environment agriculture (CEA) is a rapidly growing sector that presents unique challenges and opportunities in ensuring food safety. This manuscript highlights critical gaps and needs to promote food safety in CEA systems as identified by stakeholders (n=47) at the Strategizing to Advance Future Extension and Research (S.A.F.E.R.) CEA conference held in April 2023 at The Ohio State University’s Ohio CEA Research Center. Feedback collected at the conference was analyzed using an emergent thematic analysis approach to determine key areas of focus. Research-based guidance is specific to the type of commodity, production system type, and size. Themes include the need for improved supply chain control, cleaning, and sanitization practices, pathogen preventive controls and mitigation methods and training and education. Discussions surrounding supply chain control underscored the significance of the need for approaches to mitigate foodborne pathogen contamination. Effective cleaning and sanitization practices are vital to maintaining a safe production environment, with considerations such as establishing standard operating procedures, accounting for hygienic equipment design, and managing the microbial communities within the system. Data analysis further highlights the need for risk assessments, validated pathogen detection methods, and evidence-based guidance in microbial reduction. In addition, training and education were identified as crucial in promoting a culture of food safety within CEA. The development of partnerships between industry, regulatory, and research institutions are needed to advance data-driven guidance and practices across the diverse range of CEA operations and deemed essential for addressing challenges and advancing food safety practices in CEA. Considering these factors, the CEA industry can enhance food safety practices, foster consumer trust, and support its long-term sustainability.

Indoor, soilless production—often referred to more broadly as controlled environment agriculture (CEA)—is increasingly used for the cultivation of leafy greens. Minimal information is currently available regarding food safety practices during production and distribution of leafy greens grown within indoor, soilless environments in the United States (U.S.). This study aimed to describe production challenges and implementation of good agricultural practices among CEA growers. Data collection methods included semi-structured interviews (N = 25) and a supplemental online survey completed by growers (N = 12) in the U.S. Out of 18 total responses (i.e., multiple responses allowed per completed survey), survey data indicated that lettuce (n = 5; 27.8%) was the most commonly grown leafy green, followed by culinary herbs (n = 3; 16.7%) and arugula (n = 3; 16.7%). Most growers (n = 7; 58.3%) grew other agricultural products, specifically other crops in addition to leafy greens. Revenue from sales ranged from US$500 000 per year. Meanwhile, nearly half (n = 5; 45.5%) of respondents (N = 11) were uncertain whether their produce was subject to the FSMA Produce Safety Rule. Most survey respondents used vertical farming techniques (5 out of 11; 45.5%) or some variety of greenhouse (4 out of 11; 36.4%). Based on 35 total responses, leafy greens were most commonly sold to “Commercial Restaurants” (n = 7; 20.0%), “Grocery Stores” (n = 7; 20.0%), “Institutional Foodservice Establishments (hospitals, schools, childcare, long-term care)” (n = 6; 17.1%), and “Wholesaler/Distributers” (n = 6; 17.1%). The 11 interview questions elucidated three major themes: contextual, barriers to risk management and regulatory compliance, and research needs. Thirteen subthemes were identified, and an example of a subtheme within each major theme, respectively, includes worker hygiene and training, regulatory and certification environment, and risk assessments of individual issues.

As of August 2023, the two U.S. Food and Drug Administration (FDA) official detection methods for C. cayetanensis are outlined in the FDA Bacteriological Analytical Manual (BAM) Chapters 19b (produce testing) and 19c (agricultural water testing). These newly developed detection methods have been shown to not always detect contamination when present at low levels. Yet, industry and regulators may choose to use these methods as part of their monitoring and verification activities while detection methods continue to be improved. This study uses simulation to better understand the performance of these methods for various produce and water sampling plans. To do so, we used published FDA test validation data to fit a logistic regression model that predicts the methods’ detection rate given the number of oocysts present in a 10-L agricultural water or 25 g produce sample. By doing so, we were able to determine contamination thresholds at which different numbers of samples (n = 1, 2, 4, 8, 16, and 32) would be adequate for detecting contamination. Furthermore, to evaluate sampling plans in use cases, a simulation was developed to represent C. cayetanensis contamination in agricultural water and on cilantro throughout a 45-day growth cycle. The model included uncertainty around the contamination sources, including scenarios of unintentionally contaminated irrigation water or in-field contamination. The results demonstrate that in cases where irrigation water was the contamination source, frequent water testing proved to be more powerful than produce testing. In scenarios where contamination occurred in-field, conducting frequent produce testing or testing produce toward the end of the season more reliably detected contamination. This study models the power of C. cayetanensis detection methods to understand the sampling plan performance and how these methods can be better used to monitor this emerging food safety hazard.

Cover crops are plants seeded before or after cash crops to improve soil health, reduce weed pressure, and prevent erosion. Cover crops also produce various antimicrobial secondary metabolites (i.e., glucosinolates, quercetin), yet the role of cover crops in moderating the population of human pathogens in the soil has rarely been investigated. This study aims to determine the antimicrobial capacity of three cover crop species to reduce the population of generic Escherichia coli (E. coli) in contaminated agricultural soil. Four-week-old mustard greens (Brassica juncea), sunn hemp (Crotalaria juncea), and buckwheat (Fagopyrum esculentum) were mixed into autoclaved soil and inoculated with rifampicin-resistant generic E. coli to achieve a starting concentration of 5 log CFU/g. The surviving microbial populations on days 0, 4, 10, 15, 20, 30, and 40 were enumerated. All three cover crops significantly reduced the population of generic E. coli compared to the control (p < 0.0001), particularly between days 10 and to 30. Buckwheat resulted in the highest reduction (3.92 log CFU/g). An inhibitory effect (p < 0.0001) on microbial growth was also observed in soils containing mustard greens and sunn hemp. This study provides evidence for the bacteriostatic and bactericidal effect of particular cover crops. More research regarding the secondary metabolites produced by certain cover crops and their potential as a bio mitigation strategy to improve on-farm produce safety is warranted.

In 2021, the U.S. Food and Drug Administration (FDA), the Centers for Disease Control and Prevention (CDC), and state partners investigated a multistate outbreak of Salmonella Typhimurium illnesses linked to packaged leafy greens from a controlled environment agriculture (CEA) operation in Illinois. Thirty-one illnesses and four hospitalizations were reported in four states, with a significant epidemiologic signal for packaged leafy greens from Farm A. A traceback investigation for leafy greens included seven points of service (POS) with food exposure data from eight ill people. Each POS was supplied leafy greens by Farm A. FDA investigators observed operations at Farm A and noted that 1) the firm did not consider their indoor hydroponic pond water as agricultural water, 2) condensate dripping from the chiller water supply line inside the building, and 3) unprotected outdoor storage of packaged soilless growth media and pallets used for finished product. FDA collected 25 product, water, and environmental samples from Farm A. The outbreak strain was recovered from a water sample collected from a stormwater drainage basin located on the property adjacent to Farm A. In addition, an isolate of Salmonella Liverpool was recovered from two indoor growing ponds within the same growing house, but no illnesses were linked to the isolate. Farm A voluntarily recalled all implicated products and provided their root cause analysis (RCA) and return-to-market plan to FDA. While the source and route of the contamination were not determined by the RCA, epidemiologic and traceback evidence confirmed the packaged salads consumed by ill persons were produced by Farm A. This was the first investigation of a multistate foodborne illness outbreak associated with leafy greens grown in a CEA operation. This outbreak demonstrated the need for growers using hydroponic methods to review their practices for potential sources and routes of contamination and to reduce food safety risks when identified.

Radiocesium dynamics data during food processing are required for the realistic estimation of internal radiation content in food. Radiocesium contamination of leafy vegetables can occur externally due to the adhesion of fallout and/or resuspension from the air, and internally from soil via the root transport. Information regarding the dynamics of both surface and internal radiocesium contamination during food processing is required; however, such information for leafy vegetables is limited compared to other major agricultural products. In this study, the effect of washing on the removal of surface radiocesium contamination by resuspended materials and that of cooking (grilling, boiling, and microwave heating) on internal radiocesium contamination were investigated using komatsuna (Brassica rapa var. perviridis), a leafy vegetable. The surface-contaminated samples were experimentally grown in a difficult-to-return area in Fukushima Prefecture, which has not yet been decontaminated. The internally contaminated komatsuna were obtained after experimental cultivation in a greenhouse with soil containing 137Cs and no surface contamination. The concentration of 137Cs in surface-contaminated komatsuna was reduced to approximately half (processing factor: 0.55) after washing with water. However, the annual processing factor ranged from 0.12 to 0.95, suggesting that the growing environment and climatic conditions may affect the removal rate of radiocesium by washing. Internal contamination of 137Cs was removed by 23% and 14% by boiling and grilling, respectively, but no effect was observed for microwaving. Moreover, the concentration of 137Cs decreased by 0.66-fold after boiling, while it increased by 1.19- and 1.20-fold after grilling and microwaving, respectively. Therefore, boiling was found to be preferable than grilling or microwaving for radiocesium removal.

Many food safety issues have occurred in Taiwan during the past decade. Therefore, in 2016, the Taiwan government proposed the "Five rings of food safety" policy to comprehensively protect consumer food supply. Among these policies, the "4-labels-1-Q" approach was adopted to ensure the selection of "retrospective foods" with traceable labels. Hence, this study investigated the association between the degree of recognizing the "4-label-1-Q" food traceability system and risk perceptions, in addition to whether a consumer's purchase intention of fresh foods with food labels changed after enlightenment using an educational film on food labels. In this study, the subjects were defined as the family's main food purchasers. Subsequently, 290 valid questionnaire interviews and film educational materials were administered in Tainan markets and stores. Results showed that risk perception for labeling was significantly affected by label knowledge. Alternatively, age, educational level, and the degree of risk perception influenced purchase intention. Results also showed that after administering the video intervention, the label knowledge and purchase intention increased significantly. However, film education after adjustment for age, educational level, income, and purchase places insignificantly affected risk perception, especially for those who had lower educational levels, including those over the age of 65. First, the public's trust can be boosted through label education among age groups using different channels and methods. Therefore, in the future, encouraging the sale of labeled foods in traditional markets would be a useful strategy. Second, the age, educational level, income, and risk perception of the participants significantly affected the purchase intention. Thus, in the future, this study can be a reference for designing risk communication strategies and promoting traceable agricultural products.

Throughout these past decades, climate change has featured among one of the most complex global issues. Characterized by worldwide alterations in weather patterns, along with a concomitant increase in the temperature of the Earth, climate change will undoubtedly have significant effects on food security and food safety. Climate change engenders climate variability, which are significant variations in weather variables and in their frequency. Both climate variability and climate change are thought to threaten the safety of the food supply chain through different pathways. One such pathway is their ability to exacerbate foodborne diseases by influencing the occurrence, persistence, virulence and, in some cases, toxicity of certain groups of disease-causing microorganisms. Food safety can also be compromised by various chemical hazards such as pesticides, mycotoxins and heavy metals. With changes in weather patterns such as lower rainfall, higher air temperature and higher frequency of extreme weather events amongst others, this translates to emerging food safety concerns. These include shortage of safe water for irrigation of agricultural produce, greater use of pesticides due to pest resistance, increased difficulty in achieving a well-controlled cold chain resulting in temperature abuse, or occurrence of flash floods which cause run-off of chemical contaminants in natural water courses. Together, these can result in foodborne infection, intoxication, antimicrobial resistance and long-term bioaccumulation of chemicals and heavy metals in the human body. Furthermore, severe climate variability can result in extreme weather events and natural calamities, which directly or indirectly impair food safety. This review discusses the causes and impacts of climate change and variability on existing as well as emerging food safety risks, and also considers mitigation and adaptation strategies to address the global warming and climate change problem.