Food Safety Considerations for Nutrition Science

Public awareness of food safety is also at an all-time high, according to Yiannas. More sensitive tests for microbes, better tracking of food purchases, and a 24-hour news cycle have made foodborne diseases a hot topic. Yiannas cited an outbreak of Salmonella typhimurium in 2008. DNA fingerprinting of the outbreak strain allowed epidemiologists to link the widely scattered cases to a single peanut butter processing company. The resulting scandal prompted Congress to develop the Food Safety Modernization Act (FSMA), overhauling the nation's food monitoring system.

Globalization is also reshaping the food landscape, with ingredients for a single meal often coming from dozens of countries; but eating local food is not necessarily safer. "The world's largest E. coli outbreak, in Germany, [was] traced back to local food—a small local organic sprout farmer," Yiannas said, adding that "outbreaks are becoming larger and the world is becoming smaller." With the rise of social media, outbreaks of fear are also gaining momentum. He cited the "pink slime" controversy, in which sales of a beef product with no safety problems plummeted because a groundswell of consumers suddenly found it disgusting.

A tangled food web

Robert E. Brackett, a professor of food science and nutrition at Illinois Institute of Technology, gave the second keynote presentation, which also examined the disjunction between real and perceived food safety risks. Many types of risk arise in food processing, and Brackett reviewed the thorny problem of balancing them. Even testing for pathogens in food carries a danger of false positive and false negative results. "This [particular problem] is something that troubles the industry, because consumers want more testing, but when it comes up negative they're assuming there's nothing there, and that may not be the case," Brackett explained.

While consumers often find acute food safety problems such as Salmonella infection alarming, chronic risks from normally occurring substances such as saturated fats take a larger toll on public health. Worse, a major scare focusing on a particular food can lead to poor dietary choices. Brackett described a recent outbreak of pathogenic Escherichia coli traced to fresh spinach, which led many people to give up all leafy green vegetables. "On one hand you had the regulatory agencies saying you'd better not eat spinach right now, on the other hand you had nutritionists saying we need to have more fresh produce," he said.

A general backlash against the food industry also leads some consumers to see risks where none have been found; genetically modified crops, irradiated foods, and pasteurized juices have all run afoul of such fears. But rejecting technologies that make food safer and more affordable also carries economic risks, such as rising prices and company bankruptcies. Government interventions do not necessarily help; consumers and industry groups may consider the government's reaction to a food scare inadequate or inappropriate and react accordingly at election time.

Untangling this knot of interlocking risks now falls to government regulators and industry managers. The FSMA directs the U.S. Food and Drug Administration (FDA) to conduct "science-based risk analysis" of foods. For food companies, a credible risk management strategy is an essential part of the business plan. "When there's an outbreak or when there's a food safety problem, the brand is sometimes very badly harmed, irreparably in some cases, and the shareholders don't like that," Brackett explained.

To assess risks, Brackett recommends the approach outlined in a 1994 National Academy of Sciences report, which argued for broad risk analyses rather than narrow, strictly technical discussions. Major components of this strategy include questioning underlying assumptions about a perceived risk and getting input from parties that might be affected. As an example, Brackett presented data on Listeria monocytogenes, a bacterium commonly associated with processed meats. Deli meats are indeed the top source of L. monocytogenes infection, but the second most common source is pasteurized milk, a food most experts consider safe. Meanwhile, the world's largest and deadliest outbreak occurred in 2012 as a result of contaminated cantaloupe, a source nobody in the industry had expected. "It's important to include a much broader consideration of the other risks that you may not have thought about," Brackett concluded.

Companies may respond more rationally to food scares, at least in an economic sense. After a recall of one brand of peanut butter, other brands increased their prices despite stable production costs. Economists predict exactly that outcome when fewer companies compete in a market. "When food safety regulation affects and increases consolidation of the industry, I think that's something that we have to watch out for, because consumer welfare is [affected] when the cost of food goes up," Salin said.

Houston, we have a pathogen

William H. Sperber of The Friendly Microbiologist argued that regulators should also take a rational approach to food safety, employing rigorous science as a basis for regulations. He began by describing a central principle in modern food safety, the hazard analysis and critical control points (HACCP) system, which he and his colleagues developed 40 years ago. At the time, Pillsbury, NASA, and the U.S. Army were collaborating to prepare safe foods for the military and astronauts. It was Sperber's job to analyze foodborne hazards for the program. His HACCP approach became the standard for the food industry in 1975, and is now part of the Codex Alimentarius, which sets food standards internationally.

A HACCP analysis begins with careful documentation of a product, its production process, and its intended uses. A multidisciplinary team then finds potential hazards in the production process, identifies critical control points where manufacturers can reduce those hazards, and develops detailed specifications and plans for managing each control point. Critical control points include such steps as pasteurization, canning, and acidification of foods.

HACCP does not work for foods that lack critical control points, a fact Sperber says regulators have ignored in recent years. "[HACCP's] early success unexpectedly created the false expectation that all foods could be produced and marketed free of pathogens," he said. That expectation led the FDA and USDA (U.S. Department of Agriculture) to create "HACCP" rules for products such as raw seafood and unpasteurized juice, whose production lacks critical control points. Instead of misusing the term, Sperber argues that the agencies should have acknowledged that such foods are inherently unsafe, and that consumers are responsible for avoiding them or cooking them properly to destroy pathogens.

User error

Dane Bernard of Bold Bear Food Safety gave the session's final talk, reviewing the roles of government regulators, industry leaders, consumers, and public figures in food safety. Each group views the problem differently. "My perception of what is an acceptable level of protection that I'm going to provide with a raw chicken product that I'm going to sell is probably different than your perception of what that level of protection should be," Bernard said. The difference is important: current regulations frequently use the term "acceptable level of protection" without rigorously defining it.

Regulators are clearer about the responsibility for food safety, placing most of the burden on industry. That pattern holds not only at the federal level but also in state and local food handling rules. Within the food industry, most of the regulations focus on food processors and retailers rather than on farmers. "The manufacturing sector ... is the neck in the hourglass, everything has to flow through there; that's where raw materials are transformed into something somebody can eat," Bernard said.

The weakest link in the food chain, however, may be at the end. Bernard described a 2006 outbreak of Salmonella that was traced to a particular brand of uncooked packaged chicken Kiev. In accordance with regulations, the manufacturer included cooking directions and warning labels saying to bake the meat until it reached a 165° Fahrenheit internal temperature. Nonetheless, some consumers apparently failed to follow the instructions, and got sick.

Public figures can also be part of the problem. Bernard pointed to the new phenomenon of food "influencers" on social media, some of whom have achieved tremendous commercial success while routinely making unproven and dangerous claims. "I wish [influencers] would provide balanced information," Bernard said, but there is little incentive for them to do so.

The scope and size of a foodborne outbreak tends to decrease as the point of contamination gets closer to the consumer. Foods contaminated in a restaurant or home may infect a handful of people, but produce that picks up a pathogen on a farm can sicken thousands across wide geographical areas. An outbreak of E. coli strain O157:H7 in 2006, for example, stemmed from spinach contaminated on a farm, and caused an estimated 4000 infections across 26 states and parts of Canada.

Sprouts can be particularly dangerous because their manufacturing process entails soaking soil-contaminated seeds in water, an ideal environment for culturing pathogens. Since 1988, there have been at least 55 outbreaks of foodborne pathogens linked to sprouts. "There's one product that I would say almost universally ... food microbiologists don't eat, and that is sprouts," Harris said.

Keeping pathogens down on the farm

Manpreet Singh of Purdue University talked about strategies for combating pathogens on foods from animals, not only meat but also eggs, milk, and seafood. These foods can harbor a range of dangerous microbes, including such newsmakers as Salmonella, Clostridium, and pathogenic strains of E. coli. As Americans increasingly get their meals to go, Listeria monocytogenes, long associated with processed meats, is also becoming more common.

Pathogens can reach animal products from several sources, including through horizontal transmission from one animal to the next and in contaminated feed or water, unsanitary living environments, and unclean slaughterhouse and dairy processing facilities.

In response to outbreaks, food producers have tried to limit some of those sources of transmission, starting at the farm. "There used to be a time when anybody could walk up to a farm and check the animals out ... I don't think that's true anymore," Singh said. He added that large modern farms now require visitors to sign in and out and wear protective coveralls to limit the risk of bringing in new pathogens. Farmers also test animals and carcasses for a wide range of microbes, quarantine new arrivals to prevent animal-to-animal disease introductions, and use feed additives to reduce pathogen loads in animals' guts.

Slaughtering and processing facilities are also subject to scrutiny, but some industry practices are inherently risky. "The majority of the poultry in the U.S. is chilled by immersion chilling," Singh said, explaining that 20 000 chicken carcasses may be submerged at a time in one large pool of cold water for cooling. A single dirty bird can then contaminate the entire batch. The alternative air-chilling method cools the poultry as it hangs in the air on individual hooks, reducing the risk of cross-contamination considerably. This technique is mandatory in Europe but not popular in the U.S.

Echoing Bernard's presentation, Singh agreed that consumers and food preparers carry considerable responsibility for food safety, especially with animal products. Maintaining correct storage temperatures, cooking foods properly, and cleaning the preparation area are all critical but poorly monitored risk-reduction measures. "At each and every step we need to have effective control measures so that the hazard is controlled," he said.

Chia pets

Jeffrey Farber of the Bureau of Microbial Hazards at Health Canada finished the session with a talk about low-moisture foods, a category traditionally considered safe; drying food is one of the oldest methods of preserving it. Paradoxically, the same low moisture that prevents microbes from growing can also help preserve them, allowing pathogens to survive for months or years.

Even time-tested preparation methods do not guarantee safety. Farber described an outbreak of Salmonella traced to contaminated chia seeds. "It's actually one of the oldest cultivated crops, and it goes back centuries, basically back to the Aztec tribes in Mexico," he said. Farmers harvest the seeds, moisten them with water, leave them overnight to sprout, and then dry them on trays in the sun before grinding them into a powder. The resulting food is high in protein, dietary fiber, and antioxidants. However, the processing does not reliably kill bacteria, so seeds that are contaminated initially will yield contaminated chia powder. Contaminated chia caused 63 cases of disease in Canada during one outbreak, with many patients hospitalized.

Other dry foods, such as milk powder, spices, and tea, have had similar problems. Twenty outbreaks have been linked to tree nuts, and 44 to confections and chocolate.

Pathogens can contaminate low-moisture foods in several ways. Soil left on crops, inadequately cleaned equipment in a processing facility, and raw material added to a product after processing can all result in foodborne illnesses. Heat treatment can kill pathogens very rapidly, but only if the food is heated while wet. "Microorganisms in the moist state are very susceptible to heating; however ... the heat resistance of microorganisms goes up dramatically in the dried state," Farber said.

That resistance can also make it hard to decontaminate manufacturing facilities. Farber cited a 1998 outbreak of Salmonella agona linked to toasted oat cereal, which prompted the manufacturer to disinfect an entire plant. In 2008, the same strain contaminated cereal from the same plant, possibly as a result of construction workers removing an old wall that had harbored the bacteria for a decade. Farber advocates including a robust inactivation step like moist heat treatment in low-moisture food processes, and using indicator strains of bacteria, common contaminating strains that are difficult to destroy but easy to test for, to monitor facility hygiene.

To correct those deficits, the investigators convened focus groups and developed a marketing campaign, using a combination of social media, table tents in dining halls, posters, online videos, and special on-campus events. "If somehow you blocked out the table tents, you blocked out the posters, whatever, we were there in your face having these fun events," Byrd-Bredbenner said. Follow-up surveys showed that the advertising blitz caused a 10%–15% improvement in students' food safety knowledge and increased the likelihood of hand washing. The team also did a similar project to improve food safety knowledge in middle school children.

A game of risk

Benjamin Chapman of North Carolina State University also emphasized the need for tailored messages for different audiences, particularly when talking about the nebulous concept of risk. He began with a story about a colleague who approached him to confess that he drinks unpasteurized milk illegally imported into the state. "We engaged in this conversation about why does he drink raw milk? He talked about really distrusting the food industry and really looking at science poorly," Chapman said.

The complexity and contradictions in people's views, and the probabilistic nature of risk, make food safety risks hard to discuss. Chapman advocates being open and frank about the uncertainties. That is not the approach the food industry has taken traditionally. "We don't often talk about the risks associated with certain types of foods," he said. The trend, he added, is to communicate, "Everything is safe ... but there are risks associated with it."

The rise of the "food evangelists." (Image courtesy of Benjamin Chapman)

To get this seemingly contradictory message across, food safety advocates need to start by understanding the audience, especially identifying whom people trust. Chapman cited the Abuela Project, in which researchers focused on queso fresco, a popular Hispanic-style cheese frequently contaminated with Listeria. Instead of using generic advertising messages, the researchers educated older women in the Hispanic community about the risks of preparing the cheese, as those women were viewed as authorities on food. Chapman argued that a similar approach could work with online "influencers" who create or amplify misinformation. "We in this room are not trusted by the people we're really trying to communicate to, so ... how do we find the people that are trusted to get the messages out?"

Condiment crush

Marjorie Nolan Cohn and her colleagues at the Academy of Nutrition and Dietetics tackled the food safety communication problem with a website and an accompanying smart phone application called "Is My Food Safe?" The website offers recipes as well as videos on home food safety, the importance of hand washing, and tips for finding a dietician. The app focuses on questions people have as they work in the kitchen.

The "Is it Done?" section of the app covers cooking temperatures, a longstanding problem in food safety. "The challenge for us is that consumers are not using food thermometers," Cohn explained. In surveys, only 20% of Americans say that they regularly use a food thermometer, but even that is likely an overestimate. Respondents could be using the thermometer incorrectly or lying about their compliance with safety recommendations. The developers hope that the app will improve survey results by providing consumers with an easy reference for safe cooking temperatures.

The "Is My Food Safe?" app answers consumers' cooking and food handling questions. (Image courtesy of Marjorie Nolan Cohn)

By looking at the "Time to Toss" section, cooks can answer the age-old question of when to throw away leftovers. Some of the answers might be surprising. "There is that perception that certain foods are always safe, like condiments. How many people open condiments and then they are in your refrigerator, on the door probably, for years?" Cohn asked. Most condiments have recommended shelf lives of only a few months after opening.

The final section of the app provides an interactive quiz on kitchen safety and food handling, including such seldom-checked items as refrigerator temperatures. To date, the app has had 70 000 downloads, "which honestly isn't too bad considering it's a food safety app and not ... Candy Crush," Cohn said.

Panel discussion

The meeting concluded with a panel discussion, in which speakers from the final session tackled questions and comments from the audience. One question about the difficulty of discussing food safety with the media prompted several suggestions for better press communication. Chapman noted that he participates in over a hundred media interviews in a year, and tries to emphasize both the importance of food safety and the uncertainties surrounding foodborne pathogen risks. Byrd-Bredbenner agreed that media outreach is essential: "I think a lot of the responsible media folks really would like to have some information, but they often don't know where to go to get it," she said.

In a reply to Cohn's presentation, an audience member pointed out that recommended food shelf lives are sometimes arbitrary, especially for acidic condiments. Cohn conceded the point but argued that consumers need clear answers rather than vague qualitative guidelines. "I'll eat a yogurt if it's two days expired and it smells okay, but I'm not going to tell [the public that]," Cohn said. A more insidious problem is that the USDA and FDA often disagree on shelf lives, creating two conflicting standards.

Panelists also delved further into the problem of social media influencers and manufactured controversies. Chapman argued that the food industry's tradition of concealing information will not work in the new media world. "There are things that we know about that are not the most appetizing, and the influencers want to know that stuff," he said, adding that "those influencers want the sciencey stuff."