(This is the introduction to a five-part series on produce safety by Roy E. Costa, R.S., M.S., a registered professional sanitarian and founder/owner of Environ Health Associates Inc. )
Many nutritional experts consider fresh fruits and vegetables to be a vital part of a healthy diet, and the American public shares this perception. As a result, there has been a significant increase in production of these healthful products, with the total value of fresh market vegetables now worth an estimated $25 billion in 2013 (up from $15 billion in 2001). With this growth has also come the realization that, in spite of the health benefits, fresh produce carries a risk of causing foodborne illness. CDC recently estimated that perhaps 5 million cases of foodborne illness each year in the U.S. are attributed to fresh fruits and vegetables.
At least some of the vast produce industry has been operating under a voluntary set of FDA food-safety guidelines since 1998 when the agency published its Guide to Minimize Microbial Food Safety Hazards for Fresh Fruits and Vegetables, but the actual rate of compliance is not known. Although there has been little enforcement of these FDA guidance documents, they have become the basis for industry best practices. Adherence of suppliers to these standards is a requirement of buyers, and virtually all major suppliers carry certification of their conformance to some accepted standard. The Food Safety Modernization Act of 2011 promises sweeping changes to food safety in the produce industry, but concerns still remain about FDA’s ability to meet its mandates.
Flaws in the voluntary model
While voluntary standards are in place for a sizable portion of the industry and likely are producing a beneficial effect, recent events have revealed problems in the voluntary system. High-profile outbreaks in previously certified establishments have resulted in questions about the value of audits as a means of assuring the safety of suppliers and the role of third-party auditors. One of the major issues is that the third-party standards for the fresh produce industry may lack scientific validity. Similarly, there is also a lack of comprehensive requirements for the construction of facilities and the required utilities. At the grower level, auditors could benefit from better information about the application of manure; safety standards for irrigation water, well construction and land use; and setbacks to sources of pollution in growing areas, just to name a few of the unresolved issues.
The distribution chain of fresh produce is complex. Growers may sell directly to consumers through farmer’s markets, or ship directly from farms to distribution centers; typically, however, the industry relies upon packinghouses to package and preserve these perishable goods and ready them for further distribution and marketing. Repacking operations may recondition and repackage products and further redistribute them. Finally, processing and fresh-cut operations provide “value added” services; fresh cut produce is now the second fastest selling item in grocery stores.
Process water in packing and processing facilities can be a source of pathogens, especially when water is reused and products are commingled in a common water application. While water-process controls are quite well understood, the science is lacking as to the value of antimicrobial applications to assure the safety of fruits and vegetables. Currently, no antimicrobial formulation has a USDA or FDA registration for use on whole fruits and vegetables to destroy human pathogens, and the agencies have not exercised legal authority to set such standards.
Our ability to effectively apply basic sanitation principles to farming methods may also be limited by ever-present sources of environmental contamination. Farming has co-existed with wild animals and domestic animal production for millennia, but only in recent times has this relationship been recognized as a vector for disease transmission. The feces of cattle and wild animals, including birds, are significant risk factors for the spread of “zoonotic” pathogens. However, completely excluding animals in farming environments is fraught with difficulty. There are two primary reasons for this: The first is that wild animals, especially deer, feral pigs, small ground animals such as mice, and birds easily invade growing areas. The second is that animal husbandry is traditionally located within crop-growing regions, often coexisting with them. The potential for irrigation water to become contaminated with the feces of animals and to further spread pathogens makes the situation even more complex.
Infectious agents such as Salmonella and pathogenic strains of Listeria and E. coli picked up on the farm can easily survive on plant material and later contaminate packing and processing environments. Whereas certain whole fruits and vegetables may be protected from microbial invasion by an outer skin or rind, processing removes these natural barriers. Once the nutrient-rich tissues are exposed, pathogens can colonize them and multiply. These factors make sanitation controls for all produce, and especially processed fruits and vegetables, highly critical for safety.
The points in the supply chain where produce can become contaminated are numerous, requiring preventive measures anytime these products are handled. There are several well-recognized commodities with a high risk of spreading foodborne pathogens, e.g., leafy greens, most sprouts, and cantaloupe, but all produce can become vehicles for disease transmission when exposed to contamination. This was brought home in late 2014, when caramel apples were associated with the deaths of six persons infected with Listeriosis.
One could argue that given the high volume of production, the incidence of foodborne illness attributed to produce is still relatively low. However, produce-associated outbreaks can be very widespread and the results devastating for all concerned. Food-safety professionals are becoming more familiar with applying the concepts of food hygiene in agriculture, but the art and practice of environmental sanitation in this challenging sphere is relatively new and still evolving.
(“Current Issues in Produce Safety” is a five-part series written for produce professionals and food-safety practitioners to further explore the factors that give rise to contamination in the produce supply chain and to identify the areas of food protection that need improvement. Please check back on Food Safety News for “The Packinghouse,” the first installment in the series.)© Food Safety News