Food Safety Magazine

Produce | April/May 2007

Lessons from the Food Safety Front Line

By James Gorny, Ph.D.

Lessons from the Food Safety Front Line

The spinach outbreak last fall was a tragic occurrence, and one that struck hard. We, the produce industry, can never forget the real human impact when something goes wrong in our food safety system. That is what drives food safety to be a process of continuous improvement, not a static achievement. The produce industry is on a continuum, constantly striving toward perfection, while understanding scientifically that perfection—or zero risk—is not possible. Our overall safety record is good in providing American consumers more than a billion servings of fresh produce every day. But, industry cannot rest when even rare breakdowns in food safety systems can cause such human impact as that felt last fall.

The produce industry has long been working to address food safety. In fact, the first Food Safety Guidelines for the Fresh-Cut Produce Industry was published 15 years ago in 1992, and we are now on our fourth edition. The first industry guidelines to minimize on-farm microbiological food safety risks for fruit and vegetables were developed in the mid-1990s. Put simply, food safety has been at the forefront of the produce industry’s mission to serve the American public for many years. When a tragedy such as the E. coli O157:H7 spinach outbreak occurs, we are committed to learning all lessons possible and incorporating that knowledge into continuous process improvement.

So, what has the industry done to address this outbreak, and what are we doing now to improve food safety practices from field to table? When the spinach outbreak occurred, the entire industry immediately pulled all spinach from shelves nationwide, and cooperated fully with the U.S. Food and Drug Administration (FDA) in tracking this problem back to its source. The industry also immediately began a comprehensive reevaluation of spinach production, handling and processing to make sure we were taking all appropriate steps to assure safety. This included not only the company directly involved in the outbreak, but companies throughout the spinach growing and processing sectors. While the source of the outbreak itself proved to be narrow, the entire industry joined together to make sure we collectively are addressing all the common risk factors that can be associated with fresh leafy greens grown outside in nature and consumed without cooking.

During the past several months, all stakeholders in fresh produce safety have refocused efforts through various initiatives to improve existing measures and systems and to identify the next steps to best assure food protection and quality throughout the supply chain. At the forefront of these activities are joint efforts by regulators, industry and researchers to develop more practical guidelines for farmers, processors, distributors and foodservice/retail establishments and to strengthen the regulatory framework.

Prevention is Key to Safety Assurance
Many of the most important learnings for industry as a result of the spinach contamination issue have been reminders of what we already know—and what we don’t. Fruits and vegetables that have been minimally processed and altered in form—via peeling, slicing, chopping, shredding, coring or trimming, with or without washing or other treatment, prior to being packaged for distribution, sale and consumption—have not undergone steps designed to kill pathogens that may be present. The foodborne illness outbreak associated with E. coli O157:H7 in fresh packaged spinach reminds all stakeholders that there is no “silver bullet” technology or testing program that will eliminate microbial contamination of fresh produce. Although studies have shown that intervention methods utilizing technologies such as antimicrobial and ozone treatments, high pressure processing and flash pasteurization can mitigate the transfer, survival and growth of microorganisms on produce, no single intervention can eradicate human pathogens from these products. Thus, one of the most significant lessons we’ve learned is that prevention is the single most powerful tool in our food safety toolbox.

As the fresh and fresh-cut produce industry proceeds to develop targeted prevention measures, we will need continue to push the application of these tools back to the farm and field as far as possible and change our thinking about what measures will be most effective in reducing risk factors at each link in the supply chain. At the same time, we must be able to direct limited food safety dollars toward the areas of the highest priority so that any investment made provides a real return in produce safety improvement. Some of the more recent discussions by industry and regulatory stakeholders have centered on this challenge: With so many possible sources and methods of transmission of human pathogens to produce in the field, it is difficult to pinpoint where to focus prevention efforts to mitigate or eliminate these organisms. We can leave no stone unturned and yet by focusing on every possible vector or input our efforts will be diluted and thus ineffective. As we’ve seen in the FDA investigation report, there are many dots begging to be connected. As food safety professionals, we’ve got to connect the right ones to draw the right picture.

Of course, there are established prevention strategies that we can build upon. Good Agricultural Practices (GAPs), Good Manufacturing Practices (GMPs) and Hazard Analysis and Critical Control Points (HACCP) are all examples of established science-based prevention programs that are part of most food safety systems today. Recent events also remind us that although microbiological testing has an important role to play as an investigative tool in an outbreak situation, at the front end of a process, or to provide verification and/or validation that science-based preventive measures applied through an operation’s GAP, GMP, and HACCP programs are working, it is the weakest tool in our toolbox. Even so, this has become a major issue in the industry, particularly with regard to the trend for downstream customers to require such testing from suppliers due to legal or due diligence concerns.

However, raw agricultural commodity and finished product testing is not a preventive measure. For example, the International Commission on Microbiological Specifications for Foods (ICMSF) has published a table shows statistics that illustrate the limitations such testing. In Table 7 (name of document), if an operator takes 30 samples from a product lot that is 0.5% contaminated, there is an 86% probability that the operator will find no positives for human pathogens and accept that lot even though it is contaminated in about one out of every 200 pieces.

Further, if the goal is to achieve a 90-95% confidence level that there are no human pathogens present in a particular lot and based on trending you know the microbial contamination level is approximately 0.7%, you would have to take in in excess of 400 samples to meet that confidence level. In other words, the absence of evidence isn’t evidence of absence, as Carl Sagan said. The power of microbiological testing is that it provides us with a tool to verify or validate that our processes are in place and allows us to evaluate food safety measure efficiencies and react quickly if we see that a process has gone awry.

New Initiatives to Reduce Risk
In April 2006, the United Fresh Produce Association, the Western Growers Association and other industry groups published the Lettuce and Leafy Greens Commodity Specific Guidance, a document based on the 1998 FDA GAPs documents and customized for leafy greens. These have just been republished with a useful update to the GAPs section. The guideline identifies the most important risk factors for microbial contamination of produce commodities in the field, including water, workers, soil amendments and wildlife, and provides science-based numerical ranges that can be used for a general evaluation of the efficacy of the operation’s food safety system. A recommendation such as “Irrigate with water of quality for its intended purpose,” for example, is now supplemented with a numerical range of microbial acceptability using generic indicator organisms. These numbers can assist the grower in assessing whether the irrigation water falls within the general range considered “of quality for its intended purpose.” And importantly, the numbers can serve as “tripwires,” so that if the upper limit of that range is exceeded the operator has the opportunity earlier in the process to determine if something in the process has gone awry and thus take the appropriate measure to correct the problem.

As these metrics were written it became clear that there exist areas in which there is a significant lack of science to guide us as we develop the food safety measures we require to efficiently address microbial contamination of fresh and fresh-cut produce items. As a result, United Fresh Association identified four overarching research objectives that span the farm-to-fork continuum, applicable not only to the farm but to the processor, the distributor, the foodservice and retailer:

1. What are the sources of these human pathogenic contaminants? Are they coming from domestic animals, wild animals or people? There is a lot of good work being done by researchers, including a study being conducted at the U.S. Department of Agriculture’s Agricultural Research Service in Albany, CA, on source tracking to try to determine where these contaminants are originating. If we know the source we can more clearly focus our limited food safety resources on prevention measures that address the root of the problem. Even in the FDA’s spinach investigation report, there is no definitive identification of the source of the outbreak. A careful review of the report shows that there was a long distance of many feet between the location of the field and where the E. coli O157:H7 samples were found. This leads us to the second research question: How did the E. coli get transferred?

2. What are the most probable vectors or mechanisms of transferrence? Another research question that needs to be investigated is how human pathogens get transferred from water, air and soil onto the produce. All of the regulatory investigations into the spinach outbreak provided us with valuable information about likely vehicles of transfer but no definitive answer. The fact that FDA reports that the exact same strain of E. coli was found on land adjacent to where the positive samples were found leads to many sub-questions: Was it wind, soil or water transmission, did field workers provide the means for its movement, or did animals track it from field to field?

3. What is the microbial ecology of these organisms? We know a lot about about human pathogens such as Listeria monocytogenes in a food processing environment, but we don’t know as much about the microbial ecology of pathogens such as E. coli O157:H7 or Salmonella in the farming environment. Understanding the microbial ecology of target pathogens is key since only by gaining knowledge about their niches, harborages and lifecycles will we be able to develop better mechanisms and means to control, reduce or eliminate them. This is true particularly on the farm where we know nothing about EHECs in the environment or even the point at which the pathogen should be considered a fecal contaminant versus an environmental contaminant.

4. Once these human pathogens have been transferred onto an agricultural commodity or fresh-cut produce item, what is their potential to survive, persist and/or grow? Understanding how temperature, humidity or other factors increase a potentially hazardous microorganism’s ability to thrive and multiply is valuable information that will help us strengthen our prevention tools and mitigation strategies or technologies.

In addition to a renewed focus on supporting appropriate research, the effort to investigate and address the spinach outbreak led to an important initiative spearheaded by the leafy greens industry to adopt stringent food safety measurement criteria which can be implemented and verified across this sector of the industry. The California Department of Food and Agriculture (CDFA) has recently adopted a Leafy Greens Marketing Agreement which will serve as a means of setting rigorous measurements of safety for leafy greens from this major production region. These science-based standards include careful attention to site selection for growing fields based on farm history and proximity to animal operations, appropriate standards for irrigation water and other water sources that can come in contact with crops, prohibition of raw manure with use of only certified safe fertilizers, good employee hygiene in fields and handling, and of course, strong food safety controls in all processing plants.

Under the Leafy Greens Agreement, growers will be audited by the CFDFA to ensure that they are complying with these standards. And, they will face penalties if found to be out of compliance, with the ultimate consequence of not being allowed to sell product if they cannot do so safely. Taking a step like this toward self-regulation is a critical step in continuing to assure the public that our industry is doing everything we can to make our products safe.

In fact, many other sectors of our industry are pursuing similar efforts to define, implement and verify best practices from field to table. For example, the Florida tomato industry is at the forefront of developing good agricultural practices for their sector of the industry, and exploring various means to assure compliance across multiple growing regions outside of the state as well. Just last month, the tomato industry convened a meeting of some 50 scientists in government, academia and industry to discuss new tomato research initiatives to further reduce risk. And, of course, other regional groups are implementing similar efforts. In New Jersey, a new food safety task force put together by the state Department of Agriculture is looking at specific GAPs and training programs for their growers. Another good example is the Georgia Fruit and Vegetable Growers Association, which has its own GAPs training program to help small growers in that state better understand and apply best practices. All these efforts represent industry led initiatives to further reduce risk and ensure the safest possible produce for the public.

A Framework for Effective Regulation
It is within the context of all of these industry-driven efforts that an appropriate regulatory framework for fresh produce safety should be established. While there is much our industry can and must do, we also have to recognize the important role of the federal government. It is simply unacceptable for Americans to fear consuming those very fresh fruits and vegetables that are essential to their good health. Consumers must be able to shop in any grocery store, or order fresh produce in any restaurant, with complete confidence that their produce selection is a safe and healthy choice. Whatever low risk that might be present must be viewed as an acceptable risk, based on strong government assurance that proper food safety systems are in place, and that the benefits of consumption far outweigh the low risk.

No matter how hard our industry works, public confidence ultimately depends upon government as the final health and regulatory authority to determine proper food safety standards and ensure that they are being met. The most appropriate produce safety regulatory framework to protect public health should include three key principles:

1. Consistent Produce Food Safety Standards. Produce safety standards must be consistent for an individual produce commodity grown anywhere in the United States, or imported into this country. Consumers must have the confidence that safety standards are met no matter where the commodity is grown or processed. Because of the variation in our industry’s growing and harvesting practices in different climates and regions, flexibility is very appropriate and necessary. For example, some production areas use deep wells for irrigation while others use river water supplied from dams. Some farms use sprinkler irrigation, others use a drip system laid along the ground, and still others use water in the furrows between rows of produce. But the common factor must be that all uses of water for irrigation must meet safety standards that protect the product. That must be true whether the produce is grown in California, Florida, Wisconsin or Mexico.

2. Federal Oversight and Responsibility. Achieving consistent produce safety standards across the industry requires strong federal government oversight and responsibility in order to be most credible to consumers and equitable to producers. The FDA, which is the public health agency charged by law with ensuring the safety of the nation’s produce supply, must determine appropriate nationwide safety standards in an open and transparent process, with full input from the states, industry, academia, consumers and all stakeholders. FDA must have the ultimate responsibility to ensure that industry is complying with these standards. In the future, the produce industry must be able to stand side-by-side with government to reassure the public that together, we have done everything necessary to implement and comply with strong mandatory government standards to protect public health.

3. Commodity-Specific Scientific Approach. Finally, produce safety standards must allow for commodity-specific food safety practices based on the best available science. In a highly diverse industry that is more aptly described as hundreds of different commodity industries, one size clearly does not fit all. For example, the food safety requirements of products grown close to the ground in contact with soil are far different from those grown on trees. And, the large majority of produce commodities have never been linked to a foodborne disease. Every produce commodity is different, and the food safety regulatory approach must contain needed scientific flexibility to address specific commodities differently based on their unique production and handling practices. Government and industry alike must be careful that broad strokes do not result in requirements that should not apply to specific commodities, and do nothing to enhance safety.

Together, these three principles define a food safety regulatory policy that will most help our industry enhance produce safety, concurrent with establishing the highest level of public trust in fresh produce. Of course, any reasonable person in the food industry would want to produce only the safest possible product. But for the produce industry, somehow it seems even more important because of the healthfulness of fresh produce. With that public health imperative, we simply cannot allow fears of food safety to become linked with fresh produce. We as an industry must do all we can to prevent illnesses from ever occurring, and we will. A strong food safety regulatory framework that assures the public that appropriate safety standards are in place and are being met by the industry will help consumers enjoy an ever-increasing array of safe, healthy and nutritious fresh fruits and vegetables.

Read the sidebar "FDA Finalizes Report on 2006 Spinach Outbreak"

James R. Gorny, Ph.D., currently serves as Senior Vice President of Food Safety and Technology for the United Fresh Produce Association where he leads the association’s food safety, quality assurance, supply chain technology and food security programs on behalf of the association’s members. As United’s chief food safety officer, he advocates the membership’s interests before all relevant health and safety regulatory officials, the Bush Administration, and the Congress. He is the author and editor of numerous scientific and technical publications pertaining to the quality and safety of fresh produce. Gorny is most recently a contributor and co-editor of a book entitled The Microbiology of Fruits and Vegetables, published in August 2005 by CRC Press. He is also the 2005 recipient of the International Fresh-cut Produce Association Technical Award. He is also an adjunct professor at the University of California, where he serves as an extension educator.




FDA Finalizes Report on 2006 Spinach Outbreak

The U.S. Food and Drug Administration (FDA) and California’s Department of Health Services (CDHS) released on March 23 a joint report on an extensive investigation into the causes of an E. coli O157:H7 outbreak last fall that was associated with contaminated Dole brand Baby Spinach and resulted in 205 confirmed illnesses and three deaths. The inquiry was conducted by the California Food Emergency Response Team (CalFERT), a team of experts from FDA’s district office in San Francisco and CDHS. They were assisted by experts from the Centers for Disease Control and Prevention (CDC) and Animal and Plant Health Inspection Service of the U.S. Department of Agriculture (USDA).

The investigators successfully identified the environmental risk factors and the areas that were most likely involved in the outbreak, but they were unable to definitely determine how the contamination originated.

“The probe was a notable effort by federal, state and local officials,” said Robert E. Brackett, Ph.D., director of FDA’s Center for Food Safety and Applied Nutrition. “It yielded valuable information we can use to determine how best to reduce the likelihood of similar outbreaks.”

The report describes the painstaking detective work of the investigators following the first reports from CDC in September 2006 of an apparent outbreak of E. coli O157:H7 linked to the consumption of bagged spinach. The probe initially focused on the processing and packaging plant of Natural Selection Foods, LLC in San Juan Bautista, CA, where the contaminated products had been processed.

The next focus of the inquiry was the source of the spinach in 13 bags containing E. coli O157:H7 isolates that had been collected nationwide from sick customers. Using the product codes on the bags, and employing DNA fingerprinting on the bacteria from the bags, the investigators were able to match environmental samples of E. coli O157:H7 from one field to the strain that had caused the outbreak. Potential environmental risk factors for E. coli O157:H7 contamination at or near the field included the presence of wild pigs, the proximity of irrigation wells used to grow produce for ready-to-eat (RTE) packaging, and surface waterways exposed to feces from cattle and wildlife.

Because the contamination occurred before the start of the investigation, and because of the many ways that E. coli O157:H7 can be transferred—including animals, humans, and water—the precise means by which the bacteria spread to the spinach remain unknown.

FDA continues to work closely with its federal, state and local partners to keep produce safe from bacterial contamination.Recently, FDA recently issued a draft final guidance, “Guide to Minimize Microbial Food Safety Hazards of Fresh-cut Fruits and Vegetables,” which recommends measures to prevent microbial contamination during the processing of fresh-cut produce.

Categories: Food Types: Produce