Colorado State University Extension
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Update on Produce Safety

Edited by: Mary Schroeder, M.S., R.D. & Pat Kendall, Ph.D., R.D., Colorado State - Summer 2004

Knowing what to eat these days can be confusing. Health experts expound on the benefits of eating fresh fruits and vegetables, yet along with these benefits come a degree of risk. According to the Centers for Disease Control and Prevention (CDC), in the U.S. the number of reported produce-related outbreaks per year doubled between the period 1973 - 1987 and 1988 - 1992. The CDC estimates that, in the 1990s, at least 12 percent of foodborne outbreak-associated illnesses were linked to fresh produce items.

Why is Produce becoming a "Risky" Food?

Several reasons play a role in the increasing incidence of produce-related foodborne outbreaks. For starters, American consumers are eating about 20 pounds more fresh produce annually than we did two decades ago. Importation of fresh produce has allowed us to enjoy a wider selection of fruits and vegetables year round. However, outbreaks of foodborne disease have been traced to areas having substandard sanitation conditions and practices in developing countries where the produce is grown.

Additionally, the emergence of pathogens not previously associated with raw produce has enhanced the potential for foodborne illness outbreaks associated with raw fruits and vegetables. Among the greatest concerns with human pathogens on fresh fruits and vegetables are enteric pathogens (e.g., Escherichia coli O157:H7 and Salmonella) that have the potential for rapid growth prior to consumption or have a low infectious dose.

Plant Pathology and Foodborne Disease

Complex plant ecosystems on the surface of raw fruits and vegetables can affect a plant's ability to support the growth of pathogenic bacteria. For example, bacteria grow well on the surface of vegetables, melons and some soft overripe fruits having a pH of 4.6 or higher; in comparison, firm tomatoes are generally acidic enough to retard growth of enteric pathogens such as Shigella or E. coli O157:H7. Differences among types of plants provide microorganisms the opportunity to infiltrate cracks, crevices, and intercellular spaces as well as the seeds themselves. Pathogenic bacteria can survive for prolonged periods in or on stored dried seed, making it difficult to find the optimum mode of treatment without compromising seed quality. Additionally, the formation of biofilms on plant surfaces can encapsulate and protect pathogenic organisms, thereby reducing the effectiveness of sanitizers and other inhibitory agents.

Actions Taken

Produce is vulnerable to numerous sources of potential microbial contamination both pre- and post-harvesting, including any point during production, packing and preparation. Extensive research is underway in the areas of seed treatment, seed testing and antimicrobial treatments for fresh produce. While these methods along with training on and enforcement of good agricultural practices certainly help minimize risk, no one treatment intervention can control or completely eliminate pathogenic microorganisms on fresh produce.

To help address this complex issue, the U.S. Food and Drug Administration (FDA) has had an advisory committee in place since 1995 to investigate the association between cases of foodborne illness and fresh produce and to provide recommendations to reduce the risk of foodborne outbreaks. As a further step, FDA this summer proposed a four-part action plan designed to minimize foodborne illness associated with the consumption of fresh produce. The plan is designed to extend to all parts of the food chain, from farm through retail to consumer preparation and consumption and has four objectives:

1. Prevent contamination of fresh produce with pathogens.
2. Minimize the public health impact when contamination of fresh produce occurs.
3. Improve communication with producers, preparers and consumers about fresh produce.
4. Facilitate and support research relevant to fresh produce.

The plan's success will require collaborative efforts among both U.S. and foreign governments, state and local agencies, the private sector and consumers.

Conclusion

It is likely that a multi-faceted approach that includes sound regulatory policies with adequate enforcement, good agricultural and manufacturing practices, proper harvesting and storage, seed testing and antimicrobial treatments will be most effective in reducing the incidence of foodborne illnesses associated with fresh produce. The take-home message to consumers still remains that no matter what precautionary measures have been taken prior to fresh produce reaching their hands, it is imperative to rinse all fruits and vegetables well prior to preparing or eating.

Sources:

1. Buck, J.W., et al. 2003. Recent trends in microbiological safety of fruits and vegetables. Online. Plant Health Progress doi. 10.1094/PHP-2003-0121-01-RV.
2. USDA Center for Food Safety and Applied Nutrition. Produce Safety From Production to Consumption: A Proposed Action Plan to Minimize Foodborne Illness Associated with Fresh Produce Consumption. June 18, 2004. available at: www.cfsan.fda.gov/~dms/prodplan.html

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