Tom Karst of The Packer writes U.S. growers are using less risky irrigation sources and are sanitizing their equipment more often than 20 years ago.
Geez that’s about how long my group was doing on-farm food safety and looking at those exact questions.
Guess on-farm food safety is just a John Prine song.
Those observations are part of a new study called “Changes in U.S. Produce Grower Food Safety Practices from 1999 to 2016,” authored by economists Gregory Astill, Travis Minor and Suzanne Thornsbury.
“Since 1999, and before the implementation of U.S. Standards for the Growing, Harvesting, Packing, and Holding of Produce for Human Consumption, the share of growers who use practices that reduce the risk of microbial contamination increased,” the study concluded.
The study said fewer growers use flowing surface water for irrigation and more growers use well water. As organic production has increased over time, the study found that more growers use manure and compost. And while more growers’ fields are next to livestock, the authors said more growers use fencing around production areas.
“The most prominent example of change is the increase in frequency that growers and sanitize harvest tools,” the study said. “The decrease in growers who never wash harvest tools is drastic as is the decrease in those who never sanitize.”
Even with the increase in food safety practices, the study said more needs to be done.
“The data available for this article also demonstrates a real need to implement more frequent measures of food safety practices within this rapidly evolving industry,” the authors said.
The U.S. Food and Drug Administration, along with the Centers for Disease Control and Prevention (CDC) and state and local partners, are investigating a multistate outbreak of E. coli O157:H7 illnesses linked to romaine lettuce from the Yuma, Arizona, growing region.
The FDA, along with CDC and state partners, initiated an environmental assessment in the Yuma growing region to further investigate potential sources of contamination linked to this outbreak.
Samples have been collected from environmental sources in the region, including water, soil, and cow manure. Evaluation of these samples is ongoing.
To date, CDC analysis of samples taken from canal water in the region has identified the presence of E. coli O157:H7 with the same genetic finger print as the outbreak strain. We have identified additional strains of Shiga-toxin producing E. coli in water and soil samples, but at this time, the samples from the canal water are the only matches to the outbreak strain.
Analysis of additional samples is still ongoing, and any new matches to the outbreak strain will be communicated publicly and with industry in the region.
Identification of the outbreak strain in the environment should prove valuable in our analysis of potential routes of contamination, and we are continuing our investigation in an effort to learn more about how the outbreak strain could have entered the water and ways that this water could have come into contact with and contaminated romaine lettuce in the region.
As of June 27, the CDC reports that 218 people in 36 states and Canada have become ill. These people reported becoming ill in the time period of March 13, 2018 to June 6, 2018. There have been 96 hospitalizations and five deaths.
The traceback investigation indicates that the illnesses associated with this outbreak cannot be explained by a single grower, harvester, processor, or distributor. While traceback continues, the FDA will focus on trying to identify factors that contributed to contamination of romaine across multiple supply chains. The agency is examining all possibilities, including that contamination may have occurred at any point along the growing, harvesting, packaging, and distribution chain before reaching consumers.
The FDA, along with CDC and state partners, initiated an environmental assessment in the Yuma growing region to further investigate potential sources of contamination linked to this outbreak. To date, CDC analysis of samples taken from canal water in the region has identified the presence of E. coli O157:H7 with the same genetic finger print as the outbreak strain. We have identified additional strains of E. coli in water and soil samples, but at this time, the samples from the canal water are the only matches to the outbreak strain.
The FDA is continuing to investigate this outbreak and will share more information as it becomes available.
“More work needs to be done to determine just how and why this strain of E. coli O157:H7 could have gotten into this body of water and how that led to contamination of romaine lettuce from multiple farms,” said Dr. Scott Gottlieb, commissioner of the U.S. Food and Drug Administration, in a statement.
Bob Whitaker, Ph.D., chief science and technology officer for Produce Marketing Association (PMA), writes that because it provides inherently healthy, nutritious foods, the fresh produce industry is uniquely positioned to help solve the nation’s obesity epidemic. To do so, consumers must have confidence in the safety of the fresh fruits, vegetables, and nuts they eat and feed their families.
A green row celery field is watered and sprayed by irrigation equipment in the Salinas Valley, California USA
Following a large and deadly outbreak of foodborne illness linked to fresh spinach in 2006, the U.S. produce industry couldn’t wait for government or other direction. After finding significant knowledge gaps and a lack of data needed to build risk- and science-based produce safety programs, the industry created the Center for Produce Safety (CPS) in 2007.
CPS works to identify produce safety hazards, then funds research that develops that data as well as potential science-based solutions that the produce supply chain can use to manage those hazards. While two foodborne illness outbreaks in the first half of 2018 associated with leafy greens demonstrate the industry still has challenges to meet, CPS has grown into a unique public-private partnership that moves most of the research it funds from concept to real-world answers in about a year.
Each June, CPS hosts a symposium to report its latest research results to industry, policy makers, regulators, academia, and other produce safety stakeholders. Key learnings from the 2017 symposium have just been released on topics including water quality, cross-contamination, and prevention. A few highlights from those key learnings are summarized here, and for the full details, you can download the Key Learnings report from CPS’s website.
Know Your Water (we were doing that in 2002, long before youtube existed)
Irrigation water is a potentially significant contamination hazard for fresh produce while it is still in the field. While CPS research has revealed many learnings about agricultural water safety in its 10 years, many questions still remain. Meanwhile, the U.S. Food and Drug Administration (FDA)’s proposed Food Safety Modernization Act (FSMA) water testing requirements—which offers some challenges for producers in specific production regions—recently raised even more questions.
New CPS research illustrates the risks of irrigating with “tail water” from runoff collection ponds. With water becoming a precious resource in drought-stricken areas, the objective was to learn if tail water might be recovered and used for irrigation. We learned that differences among pond sites—for example, water sources, climate, ag management practices—can strongly influence the chemistry and microbiology of the water. Further, water pH can influence disinfection treatment strategies.[1]
CPS research continues to investigate tools for irrigation water testing, looking specifically at sample volumes,[2] and searching for better water quality indicators and indexing organisms including harnessing next-generation DNA sequencing.[3] Following a CPS-organized colloquium on ag water testing in late 2017, FDA subsequently announced it would revisit FSMA’s ag water requirements, and postponed compliance.
Bottom line, CPS research demonstrates that growers must thoroughly understand their irrigation water before they can accurately assess cross-contamination risk. CPS’s findings clearly point to the need to take a systems approach, to understand and control the entire water system to help achieve produce safety. Long term, this may mean prioritizing research into ag water disinfection systems to better manage contamination hazards that can also operate at rates needed for field production. Cross-Contamination Can Happen across the Supply Chain
While conceptually and anecdotally the fresh produce industry knows that food safety is a supply chain responsibility, research is needed that documents the role of the entire supply chain to keep fresh produce clean and safe from field to fork. At the 2017 CPS Research Symposium, research reports were presented focusing on cross-contamination risks from the packinghouse to retail store display.
In the packinghouse, CPS-funded research found that wash systems can effectively control cross-contamination on fruit, when proper system practices are implemented.[4] Post-wash, CPS research involving fresh-cut mangos also demonstrated that maintaining the cold chain is critical to controlling pathogen populations.[5] Across the cantaloupe supply chain, CPS studies show food contact surfaces—for example, foam padding—are potential points of cross-contamination.[6] See the full 2017 Key Learnings report for details, as these brief descriptions only scratch the surface of this research.
CPS studies clearly demonstrate that food safety is a supply chain responsibility—a message that must be internalized from growers and packers to transporters, storages, and retailers to commercial, institutional, and home kitchens. While translating this research into reality will present engineering and operational challenges, our new understanding of produce safety demands it. Verifying Preventive Controls
The produce industry must know that its preventive controls are in fact effective. That said, validation can be tricky. If validation research doesn’t mimic the real world, industry ends up fooling itself about whether its food safety processes work—and the human consequences are real.
Numerous scientists presented research at the 2017 CPS Research Symposium that validates various preventive controls, from heat treating poultry litter[7] to pasteurizing pistachios[8] to validating chlorine levels in wash water systems.[9] Some researchers effectively used nonpathogenic bacteria as a surrogate in their validation studies, while another is working to develop an avirulent salmonella surrogate, and another. Wang used actual Escherichia coliO157:H7 (albeit in a laboratory).
Importantly, CPS research finds that the physiological state of a pathogen or surrogate, and pathogen growth conditions themselves, are critically important to validation studies.[10] Meanwhile, suitable surrogates have been identified for some applications, the search continues for many others.
The research findings described here are just some of the real world-applicable results to emerge from CPS’s research program. To learn more, download the 2017 and other annual Key Learnings reports from the CPS website > Resources > Key Learnings page at www.centerforproducesafety.org.
We were doing these videos in the early 2000s, long before youtube.com existed, and weren’t quite sure what to do with them. But we had fun.
In Italy, monophasic S. Typhimurium represented the third most frequent Salmonella serovar isolated from human cases between 2004 and 2008. From June 2013 to October 2014, a total of 206 human cases of salmonellosis were identified in Abruzzo region (Central Italy).
Obtained clinical isolates characterised showed S. Typhimurium 1,4,[5],12:i:- with sole resistance to nalidixic acid, which had never been observed in Italy in monophasic S. Typhimurium, neither in humans nor in animals or foods.
Epidemiological, microbiological and environmental investigations were conducted to try to identify the outbreak source. Cases were interviewed using a standardised questionnaire and microbiological tests were performed on human as well as environmental samples, including samples from fruit and vegetables, pigs, and surface water. Investigation results did not identify the final vehicle of human infection, although a link between the human cases and the contamination of irrigation water channels was suggested.
Outbreak Of Unusual Salmonella Enterica Serovar Typhimurium Monophasic Variant 1,4 [5],12:I:-, Italy, June 2013 To September 2014
Eurosurveillance, Volume 21, Issue 15, 14 April 2016
F Cito, F Baldinelli, P Calistri, E Di Giannatale, G Scavia, M Orsini, S Iannetti, L Sacchini, I Mangone, L Candeloro, A Conte, C Ippoliti, D Morelli, G Migliorati, NB Barile, C Marfoglia, S Salucci, C Cammà, M Marcacci, M Ancora, AM Dionisi, S Owczartek, I Luzzi
Traceback studies mostly implicate contamination during production and/or processing. The microbiological quality of commercially produced tomatoes was thus investigated from the farm to market, focusing on the impact of contaminated irrigation and washing water, facility sanitation, and personal hygiene.
A total of 905 samples were collected from three large-scale commercial farms from 2012 through 2014. The farms differed in water sources used (surface versus well) and production methods (open field versus tunnel). Levels of total coliforms and Escherichia coli and prevalence of E. coli O157:H7 and Salmonella Typhimurium were determined. Dominant coliforms were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. No pathogens or E. coli were detected on any of the tomatoes tested throughout the study despite the high levels of coliforms (4.2 to 6.2 log CFU/g) present on the tomatoes at the market. The dominant species associated with tomatoes belonged to the genera Enterobacter, Klebsiella, and Citrobacter. Water used on the farm for irrigation considered not fit for purpose according to national agricultural irrigation standards, with high E. coli levels resulting from either a highly contaminated source water (river water at 3.19 log most probable number [MPN]/100 ml) or improper storage of source water (stored well water at 1.72 log MPN/100 ml). Salmonella Typhimurium was detected on two occasions on a contact surface in the processing facility of the first farm in 2012. Contact surface coliform counts were 2.9 to 4.8 log CFU/cm2.
Risk areas identified in this study were water used for irrigation and poor sanitation practices in the processing facility. Implementation of effective food safety management systems in the fresh produce industry is of the utmost importance to ensure product safety for consumers.
Microbiological food safety status of commercially produced tomatoes from production to marketing
Journal of Food Protection, Number 3, March 2016, Pages 392-406, DOI: http://dx.doi.org/10.4315/0362-028X.JFP-15-300
N. van Dyk, W. de Bruin, E. M. du Plessis, and L. Korsten
That research is being conducted at the Malheur Experiment Station by Joy Waite-Cusic, assistant professor of Food Safety Systems at Oregon State University.
Onions in the research plot have been irrigated with water inoculated with E. coli, some to extreme highs, Waite-Cusic said. The E. coli was applied during the last irrigation. In the sample of onions taken from the plots, the majority of them did not test positive for the bacteria, Waite-Cusic said.
In one of the latest samplings, onions were harvested one afternoon, put in bags and tested the next morning. Only 16 out of 150 onions tested positive for E. coli, Waite-Cusic said, and this from rows where the irrigation water had been artificially inoculated with 100,000 colony-forming units of generic E. coli for 100 milliliters of water.
“The soil does a good job of filtering,” experiment station superintendent Clint Shock said.
Testing showed that there was less E. coli as the water moved from the furrow or drop tape through the soil to the onion bulb.
Irrigation water has been implicated as a likely source of produce contamination by Salmonella enterica. Therefore, the distribution of S. enterica was surveyed monthly in irrigation ponds (n=10) located within a prime agricultural region in Southern Georgia and Northern Florida.
All ponds and 28.2% of all samples (n=635) were positive for Salmonella with an overall geometric mean concentration (0.26 MPN/L) that was relatively low compared to prior reports for rivers in this region. Salmonella peaks were seasonal; levels correlated with increased temperature and rainfall (p<0.05). Numbers and occurrence were significantly higher in water (0.32 MPN/L and 37%) compared to sediment (0.22 MPN/L and 17%) but did not vary with depth. Representative isolates (n=185) from different ponds, sample types, and seasons were examined for resistance to 15 different antibiotics; most strains were resistant to streptomycin (98.9%), while 20% were multidrug resistant (MDR) for 2-6 antibiotics.
DiversiLab rep-PCR revealed genetic diversity and showed 43 genotypes among 191 isolates, as defined by >95% similarity. Genotypes did not partition by pond, season, or sample type. Genetic similarity to known serotypes indicated Hadar, Montevideo, and Newport as the most prevalent. All ponds achieved the current safety standards for generic Escherichia coli in agricultural water, and regression modeling showed E. coli levels were a significant predictor for the probability of Salmonella occurrence. However, persistent populations of Salmonella were widely distributed in irrigation ponds, and associated risks for produce contamination and subsequent human exposure are unknown, supporting continued surveillance of this pathogen in agricultural settings.
Distribution and Characterization of Salmonella enterica Isolates from Irrigation Ponds in the Southeastern U.S.A.
Applied and Environmnetal Microbiology
Zhiyao Luo, Ganyu Gu, Amber Ginn, Mihai C. Giurcanu, Paige Adams, George Vellidis, Ariena H. C. van Bruggen, Michelle D. Danyluk, and Anita C. Wright
Strawberries are an important fruit in Belgium in both production and consumption, but little information is available about the presence of Salmonella and Shiga toxin-producing Escherichia coli (STEC) in these berries, the risk factors in agricultural production, and possible specific mitigation options.
In 2012, a survey was undertaken of three soil and three soilless cultivation systems in Belgium. No Salmonella spp. were isolated. No STEC was detected in the strawberry samples (0 of 72), but STEC was detected by PCR in 11 of 78 irrigation water and 2 of 24 substrate samples. Culture isolates were obtained for 2 of 11 PCR-positive irrigation water samples and 2 of 2 substrate samples.
Multivariable logistic regression analysis revealed elevated generic E. coli numbers (the odds ratio [OR] for a 1 log increase being 4.6) as the most important risk factor for STEC, together with the berry-picking season (elevated risk in summer).
The presence of generic E. coli in the irrigation water (≥1 CFU per 100 ml) was mainly influenced by the type of irrigation water (collected rainfall water stored in ponds was more often contaminated than groundwater pumped from boreholes [OR = 5.8]) and the lack of prior treatment (untreated water versus water subjected to sand filtration prior to use [OR = 19.2]).
The follow-up study in 2013 at one of the producer locations indicated cattle to be the most likely source of STEC contamination of the irrigation water.
Microbial Safety and Sanitary Quality of Strawberry Primary Production in Belgium: Risk Factors for Salmonella and Shiga Toxin-Producing Escherichia coli Contamination
The purpose of the current study was to evaluate fresh vegetables raised on the fecal contaminated water for the detection of Hepatitis A virus HAV by PCR method. Twenty nine samples were collected from 13 different locations of district Mardan and screened for the presence of HAV.
Village Bajowro near Takht Bhai was the most contaminated site having HAV in all vegetables grown over there. Water samples collected from this area proved to be contaminated with HAV. It may be concluded that fecal contaminated water is unsafe for irrigation because of the health risk associated with such practices.
The research began last year after the U.S. Food and Drug Administration released a proposed produce safety rule that would limit the amount of generic E. coli bacteria that can be present in irrigation water.
This year’s trial is much larger and researchers expect it will confirm last year’s findings, which showed bulb onions pose no risk of E. coli contamination, regardless of how they are irrigated and regardless of the water quality.
Researchers even enriched some of the water with extremely high levels of generic E. coli by using runoff water from a pasture. Still, there was no trace of bacteria when the onions were ready for packing.
“By the time we packed them out, the numbers were all zero,” said Clint Shock, director of the Malheur experiment station.
There were traces of E. coli present on the outside of some onion bulbs when they were pulled out of the soil and left on the ground to dry. But after they were cured in the field — all bulb onions in this area go through that process — and ready for packing, no E. coli was present on any of the onions.
“The results of last year showed that the bacteria died off really rapidly after they were lifted, and cured in the field,” Shock said. “And we didn’t have any generic E. coli at all on any of the onions when we packed them out.”
E. coli levels for soils and onions were recorded during growing, harvesting and processing conditions. At no time was E. coli ever detected inside of any of the onions.
Geez that’s about how long my group was doing on-farm food safety and looking at those exact questions.
