Imported Foods: Microbiological Issues and Challenges

This chapter focuses on regulatory oversight of imported foods. Despite the long history, recent changes to bolster the authority of the agencies responsible for regulating imported food have been proposed. Hence, it is important to recognize that information presented in the chapter pertains to food safety regulations that were in effect as of October 2007. The Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA) Food Safety Inspection Service (FSIS) share primary responsibility for ensuring the safety of food imported into the United States. To gain an understanding of the food safety regulatory system for imported foods, first one must sort through the alphabet soup of agencies that enforce the regulations. Customs notifies FSIS and FDA of imported foods for the agencies’ review. The chapter describes the import process. Although FDA’s statutory authority is largely limited to inspections and tests of imported foods at the U.S. port of entry, with low-acid and acidified canned foods and infant formula, FDA may request that foreign exporting firms grant FDA inspectors access to their plants. The FDA must rely on inspections at the U.S. ports of entry to determine the safety of the imported foods. While the law requires that all imported foods meet the same food safety standards as foods produced in the United States do, recent events have raised questions about the adequacy of the regulation of imported foods.

This chapter focuses on animal and human wastes as potential sources of contamination of imported foods. The amount of animal and human feces generated on a worldwide basis is enormous. The use of human wastes or wastewater for produce production in developed countries is not allowed or is strictly regulated because of the potential for transmission of enteric pathogens. Although use of highly treated domestic wastewater for food crops to be eaten raw is allowed in some states in the United States, it is seldom practiced because of potential health hazards. Of the enteric bacteria, Salmonella, Campylobacter, and Escherichia coli O157:H7 present the greatest problem because they infect a wide variety of animals besides humans. The occurrence of enteric pathogens in the environment is a reflection of the incidence of infection by the pathogen in a population. For example, various studies have indicated that E. coli O157:H7 is commonly present in animal and human wastewaters at levels of 10 to 100/100 ml of municipal sewage and 100 to 1,000/100 ml of animal wastewaters and wastewaters from slaughterhouses. The concentrations of pathogens detected in raw sewage are provided in the chapter. Animal wastes and effluents from farming operations, including manures and slurries, are frequently applied to increase the soil fertility of cropland. Multiple contamination sources and pathways pose risks to food safety, with solid and liquid waste handling and irrigation of produce and shellfish production representing major risk factors.

As background to the relevance of antimicrobial-resistant food-borne pathogens in imported food, this chapter first provides a brief explanation of the mechanisms by which antimicrobial resistance develops in microorganisms. The chapter then focuses on the prevalence of antimicrobial-resistant pathogens both in infections in humans and in food items, followed by a discussion on the Food and Drug Administration’s (FDA’s) surveillance of imported foods for this group of pathogens. The magnitude of the public health burden due to infections caused by antimicrobial-resistant food-borne pathogens differs by region and country. Foreign travel and the consumption of imported foods contaminated with drug-resistant strains were suggested as causative factors in the increased incidence of antibiotic-resistant strains of Salmonella enterica serotype Enteritidis between 2000 and 2004, with resistance to nalidixic acid coupled with decreased susceptibility to ciprofloxacin associated with infections in England and Wales. The chapter focuses on antimicrobial-resistant Salmonella isolated from FDA-regulated imported products, in particular, seafood and fresh produce. Imported foods, especially aquatic food products, can be contaminated with antimicrobial-resistant food-borne pathogens. Global trade of foods is expected to increase in dramatic proportion in the future; hence, efforts to provide greater public health protection to foods should address antimicrobial-resistant food-borne pathogens in imported food products. Global surveillance of food-borne pathogens and sharing of antimicrobial susceptibility data among developed and developing countries are also needed to monitor trends and emerging resistance phenotypes.

Conflicting issues often emerge and must be resolved in order to implement an effective strategy to improve the microbiological safety of imported food, as illustrated in the two boxed examples that follow: (i) BSE and the risk of variant Creutzfeld-Jakob Disease (vCJD) from eating beef, and (ii) Salmonella in eggs and broilers. This chapter describes the range of tools adopted to improve the microbiological safety of imported food. The proliferation of private standards and related certification raises important questions regarding their roles in ensuring the microbiological safety of imported food. International organizations play important leadership roles in efforts to improve the microbiological safety of foods. Among these organizations, the Codex Alimentarius Commission (Codex) is particularly important. The Codex standard-setting process and the standards themselves play an influential role in microbiological food safety for imported foods on several levels. In assessing the potential value of risk-based programs to improving the microbiological safety of imported foods, it is also necessary to consider how economics may challenge their value. Risk management is the identification and selection of appropriate food safety controls based on risk assessment and other factors that may be important to the risk management decision. The Hazard Analysis Critical Control Points (HACCP) approach is a prime example of the application of risk management principles in a systematic manner. Government is responsible for introducing or strengthening existing emergency response systems to respond to food bioterrorism by identifying necessary components of an emergency response program.