Foodborne illness generally isn't thought of as an environmental issue. Water quality, yes. But foodborne illness? ×Ö´®2

A look at the past 20 years suggests that viewing this public health problem from a broader environmental perspective may be the only way to achieve a lasting reduction in the number of human illnesses caused by Salmonella and other invisible, disease-causing organisms in food and water, whether in the United States or the world at large.

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This aspect of food safety is an environmental issue in several ways. First, the bacteria and other microorganisms that can cause foodborne illness-pathogens-are often a "natural" part of the environment. ×Ö´®7

• Dormant and harmless Clostridium botulinum spores are found virtually everywhere, including in soil from farms, in forests, and in the bottoms of streams, lakes, and coastal waters.
• Campylobacter jejuni bacteria, which many experts believe constitute the number one foodborne threat despite their fragility, can be found in water, soil and sewage sludge, as well as in the intestinal tracts of domestic and wild animals and birds.
• Listeria monocytogenes bacteria are often excreted by asymptomatic humans and animals and can often be found in raw cow and human milk, improperly fermented silage, leafy vegetables, soil, and food-processing environments.
• Salmonella bacteria may be shed in poultry or livestock feces, spreading from animal to animal.

Foodborne illness may also be considered an environmental problem because an action—say, a mistake—at one point in the environment can have effects that ripple far beyond that point. For example, Clostridium botulinum spores in soil don't normally cause botulism. But under certain conditions—including the absence of oxygen—the dormant spores can transform into the vegetative bacterial cells that form the botulism toxin.

An environmental approach to solving foodborne illness problems does not necessarily mean eliminating an organism at its source point. Often, that is not possible. For example, pure-looking mountain streams can carry Campylobacter bacteria from the feces of undomesticated animals and birds, and trichina parasites may well be present in game animals shot in the wild. ×Ö´®1

However, an environmental approach does mean attacking the problem at many different points in the environmental cycle of the pathogen. This approach has seen some success. ×Ö´®1

Listeriosis. After one particularly serious U.S. outbreak in 1985, public health authorities and the food industry united to attack the problem on all fronts. The Food and Drug Administration (FDA) conducted a massive examination of the production processes for soft cheese and other dairy products. The trade associations for the food industry conducted their own troubleshooting and research to determine guidelines for preventing growth of the organism in the favorable climate of food processing plants. ×Ö´®1

FSIS, despite the lack of any listeriosis cases associated with meat or poultry products, began a monitoring and regulatory program to reduce the likelihood of Listeria-contaminated processed products reaching consumers. FSIS made its program stricter after such an illness occurred, and recalls are still occasionally necessary when Listeria bacteria are detected in ready-to-eat products. Today, public health authorities continue their vigilance against this disease, which causes an estimated 1,600 cases and 400 deaths annually in the United States alone.

Salmonella and the Environmental Approach

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Salmonellosis. Salmonella has become a household word. Reducing human salmonellosis, the disease caused by Salmonella bacteria, has challenged the public health community for decades. Some strains of Salmonella cause human illness without affecting animals at all; others cause illness in animals but not humans; still others affect both. Ten strains of the bacteria cause most human illness. Foodborne Salmonella infections are caused when humans ingest "too many" Salmonella bacteria in their food. There is no minimum or maximum safe number, although usually "the dose makes the poison." That means, the more Salmonella bacteria consumed, the greater the risk of illness. The number of bacteria that will cause illness varies with the strain of Salmonella and the victim's age, immune status, and individual genetic makeup. Healthy adult volunteers have consumed millions of Salmonella without becoming ill; in actual outbreaks, as few as 10 bacteria have caused illness.

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A 1969 National Academy of Sciences Report on Salmonella recommended intervening in the Salmonella contamination cycle at various points, including animal feed production, to reduce the potential for human illness. Yet, a 1984 international symposium on Salmonella concluded, "It should be candidly recognized that raw foods of animal origin are frequently contaminated by Salmonella and that such contamination levels cannot be expected to change greatly in the near future." ×Ö´®2

Today, such a statement would be greeted with outrage—and often is, because some are still saying it. USDA takes a much more aggressive approach. In 1981, USDA made its number one food safety research priority the control and reduction of Salmonella—both at the animal producer level and in the plant. ×Ö´®2

Despite their misgivings about the possibilities for reducing Salmonella on raw products, the 1984 expert meeting made research recommendations for the production of animal feed. USDA's Agricultural Research Service has since developed and pilot-tested an experimental steam conditioner for use in making animal feed pellets. This device shows great promise in reducing the potential for recontamination of animals through Salmonella-contaminated feed, if it proves to be practical and economical for the animal feed industry.

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As a result of research it has performed over the past 2 years, FSIS has tentatively concluded that any inplant improvements to modestly reduce the spread of Salmonella from carcass to carcass will probably not have much effect on final consumer-ready products unless Salmonella on incoming poultry can also be reduced. Such research continues and there are hopeful signs, such as the finding that a certain complex sugar appears to reduce Salmonella growth in young chickens. However, a number of other promising research avenues have been inconclusive or are still being studied. One ARS researcher has said that controlling Salmonella is as difficult as finding a cure for the common cold. Today, almost no one expects to find a "silver bullet" that will solve the Salmonella problem once and for all. ×Ö´®2

Nevertheless, today the majority of scientists and public health officials believe it is possible—and imperative—to reduce microbial contamination levels as much as possible at many different points in the food chain, including the domestic animal population. What has happened to change the collective scientific mind? ×Ö´®2

One factor has been the emergence of "new" foodborne pathogens. The foodborne illness problem is no longer only a Salmonella problem. In the past 15 years, scientists have learned that:

• A toxin of the bacteria Escherichia coli 0157:H7 can cause colon and urinary infections, especially in children. Outbreaks have been traced to contaminated meat and/or water.
• The bacterium Listeria monocytogenes, formerly known to cause animal disease and occasional infections in people working with animals or drinking raw milk, can survive in many foods to cause human illness, particularly in those with compromised immune systems.
• Yersinia enterocolitica bacteria in foods as diverse as chocolate milk, mussels, and tofu can cause the disease yersiniosis. Children are most at risk for contracting the illness. In pediatric cases, the disease symptoms mimic those of appendicitis. (1972, Japan; 1976, USA)

The pathogens described above have something in common—they can all grow at refrigerated temperatures—unlike most other foodborne bacteria, which merely survive at low temperatures.

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In addition to the new pathogens, a dramatic increase in reports of foodborne illness has highlighted the importance of foodborne illness to public health. Finally, public concerns about food safety and nutrition that had steadily grown since the 1970's reached critical mass in the mid-1980's. ×Ö´®4

The controversy that has accompanied this heightened public concern about food safety has generated many positive results, among them an informal consensus among scientists, regulators, food industry associations, and consumer groups that one particular approach to food safety offers the most hope for resolving today's food safety concerns. ×Ö´®6

An ideal approach would apply to the whole food environment, from farm to table. The National Academy of Sciences, in its 1985 and 1987 reports on meat and poultry inspection, recommended just such an approach, endorsing the incorporation of the Hazard Analysis and Critical Control Point (HACCP) system at various points in the food production, processing, distribution, storage, and handling cycle.

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HACCP is a preventive, "total systems" approach to food production. It is a process control system that recognizes the compounding effect that changes in the environment may cause. However, HACCP differs from other process control systems. It seeks to determine the major problems, assess their significance and the likelihood of their occurrence, in order to prevent them.

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A HACCP system not only determines what could go wrong at different steps in a process; it also determines the critical control points in the process. These are the points at which a mistake would have the most negative effect on the safety of the final product. Thorough cooking is an obvious critical control point in almost all food-processing systems. However, depending on the product and the plant, there could be several others. Under a HACCP system, the food processor would monitor critical control points the most closely, in order to prevent safety problems in the finished product. The regulator would monitor the plant's effectiveness, including verification testing.

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Some of the risks—such as undercooking and slow, uneven cooling—are well understood. Others are not. The National Advisory Committee on Microbiological Criteria for Foods is examining some of these issues for USDA and FDA.

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For several years, FSIS officials have been encouraging the meat and poultry industry to use this risk-based, "total systems" approach to food production. The problem, however, has been that few understood what HACCP meant in practice.

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In 1991, FSIS began holding workshops at which industry and government actually determine what HACCP is, in practice. They develop model HACCP plans for several products and processes, which will then be pilot-tested and evaluated. If successful, the plans will provide the meat and poultry industry with a better way to comply with inspection requirements and at the same time to ensure uniform, consistently safe and wholesome meat and poultry products. FSIS is also working with USDA's Extension Service on increasing Extension agent and public understanding of HACCP as it applies to all aspects of agriculture. ×Ö´®1

International interest in HACCP and other environmental approaches is growing, and that is where such approaches hold perhaps the most hope of significantly reducing human suffering. The United States has one of the safest food supplies in the world, and HACCP will make it even safer.

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Yet, around the world, millions of people die each year from foodborne illness, water contamination, and simple starvation. Sometimes these deaths are related to natural disasters, and the United Nations has in fact designated the 1990's as the Decade on Natural Disasters. Foodborne illness, like other environmental problems, is ultimately a global issue. In our concern for the consumers of the United States, let us remember our responsibility to the citizens of the world. ×Ö´®5

Salmonella Enteritidis and the Environmental Approach ×Ö´®5

The egg. In recent years, many home cooks have become concerned about poached eggs, homemade mayonnaise, and other dishes using raw or lightly cooked eggs. Hospitals, nursing homes, and other institutions are using pasteurized eggs or heat processing in these recipes. ×Ö´®5

These home and institutional foodhandlers are protecting their families and their clients from possible illness caused by Salmonella enteritidis—SE for short—which could be present in some table eggs. ×Ö´®2

Until a few years ago, salmonella in eggs was not suspected, as no one knew that uncracked eggs could be a source of these bacteria. Over the last 10 years, the Centers for Disease Control observed a dramatic increase in human illness caused by SE. Epidemiologists—who might be described as public health detectives—were able to determine that people who became ill often lived in the Northeastern part of the country, and they had often eaten foods containing raw or lightly cooked eggs.

The chicken. Thoroughly cooking eggs is one effective way to prevent illness, but it doesn't attack the roots of the SE problem. In 1988, USDA's Animal and Plant Health Inspection Service (APHIS), working with other public health agencies, began researching to learn about those roots. APHIS was also concerned about solving the problem in a way that would encourage maximum cooperation from the poultry and egg industry, as well as educate consumers on the risks of mishandling eggs and foods containing eggs. ×Ö´®9

Studies have subsequently shown that certain invasive strains of SE may infect the internal organs of laying hens, passing the bacteria into the interior of eggs before they are laid. Testing under the voluntary National Poultry Improvement Plan uncovered SE in the internal organs of birds from 3 breeding flocks in 1990. These flocks have been restricted from interstate commerce. ×Ö´®1

In February 1990, USDA intensified its efforts against SE by forming the Salmonella Enteritidis task force. During its first year, the task force made significant progress. It reported that in response to reports of human SE outbreaks, testing for SE involved some 5 million chickens, 2 million of which were voluntarily destroyed. The task force identified only 12 table-egg laying flocks affected with the disease in 5 States: Maryland, Pennsylvania, Alabama, Indiana, and Delaware. Some 300 million table eggs from SE-positive farms were diverted away from the table-egg market to processing plants for pasteurization, a process that kills Salmonella. ×Ö´®6

John Mason, APHIS veterinarian and director of the Task Force, believes that only a limited number of egg-laying poultry flocks may be affected with the new invasive strains of SE. The hope is that by systematically locating those flocks and replacing them with birds free of SE, the incidence of the bacteria may be reduced and eventually eliminated. ×Ö´®4

In 1991, the task force began considering use of a more extensive environmental approach—the HACCP system. The task force believes use of the HACCP approach may be more effective in solving the SE problem sooner, because it would involve concerted efforts to reduce contamination at many different points in the food chain. SE-free feed, SE-free laying hens, good sanitation, biosecurity (a collection of good housekeeping measures designed to keep disease organisms from entering or spreading), careful refrigeration of table eggs, use of pasteurized eggs, and food-handling education programs could all help reduce SE contamination. The HACCP approach may also be fairer, the task force believes, because it does not place the burden of SE control only at the henhouse door--or the food handler's. "We've all got a stake in solving the problem," said Mason. "So we've all got to take on some of the responsibility." ×Ö´®6

?by Sharin Sachs, FSIS; and Margaret Webb, Public Affairs Specialist, Animal and Plant Health Inspection service, USDA, Beltsville, MD ×Ö´®4