If you work in the area of food and health, you already know that foodborne illness (FBI) is a major public health issue.
It affects 1 in 6 Americans annually, according to the Centers for Disease Control and Prevention (CDC). You may also know that at least two out of three FBI outbreaks trace back to food prepared outside the home—as in a restaurant, an institution, or a retail establishment.
Why? We can talk about causes, and you can probably name culprits straight out of media headlines: STEC, Salmonella, Clostridium, Listeria, Norovirus, and many other pathogens. These pathogens are everywhere, yet not every meal leads to illness (thankfully). In analyzing FBI outbreaks, the CDC identifies contributing factors. These are not the pathogens. Rather, they are the factors that allow pathogens to thrive and persist through the flow of food, ultimately causing an outbreak.
According to the CDC, the top five contributing factors to FBI in foodservice and retail food establishments are:
The FDA has conducted on-site research regarding compliance with specific FDA Food Code guidance related to these five factors. In its Report on the Occurrence of Foodborne Illness Risk Factors in Selected Institutional Foodservice, Restaurant, and Retail Food Store Facility Types, FDA analysts cited personal hygiene, time and temperature control, and protection from contamination (#2, #4, and #5) as areas most in need of improvement.
They noted, "Foodservice and retail food store operators must ensure that their management systems are designed to achieve active managerial control over the risk factors." In this short CE program, you will learn more about contributing factor #5.
Upon completion of this CE program, you will be able to:
Cross contamination is the transfer of pathogens to food.
The word "cross" sometimes confuses people. Why "cross"? It's the idea that something dangerous crosses from any item to food. For example, when your hands are unclean and you touch a slice of bread, bacteria cross from your hands over to the bread.
In food safety, most people use "cross contamination" to describe pathogens passing to a food. Technically, contamination can be anything that makes the food unsafe—even a cleanser or a food allergen.
Consider the flow of food. As each food ingredient and recipe moves through the process defined in your organization, it has multiple opportunities to become contaminated. The job of a foodservice manager is to anticipate and control each of these opportunities, or "risks". A typical flow of food begins with food being received and checked in, then transferred to storage. Later, it may be retrieved from storage and used in a recipe. Later still, the food may undergo transportation and/or holding in a service area. Finally, it may be stored again for future use.
Even a home kitchen has a flow of food. Someone brings home groceries, places them in storage, and uses foods to make meals.
While a food is following its flow in any kitchen, contamination can occur at any point. (Remember, it can even enter your doors contaminated.) Once contamination occurs, pathogens in food pose a food safety risk.
One of today's most respected food safety models, the Hazard Analysis and Critical Control Point (HACCP) system, targets controls where risks are highest and interventions can have the greatest impact. For example, foods that risk being contaminated undergo cooking to defined time and temperature standards. This mitigates the food safety risk.
However, other foods are ready-to-eat. This means they will undergo no cooking (or further cooking). An example is a sliced turkey and avocado deli sandwich. If it becomes contaminated with Staphylococcus bacteria from a foodservice worker's skin, the bacteria are likely to live on. Upon cross contamination, odds of causing an illness are higher when the food involved is ready-to-eat. Typically, there are no further controls to mitigate this hazard.
There are two typical ways that cross contamination occurs
Let's look more closely. First, Pathogens cross from one food to another food. Here are some examples:
Now we'll look more closely at the second kind of cross contamination:
Pathogens pass from food-contact surfaces of equipment or utensils to food. Here are some examples:
Cutting boards are often a focus of equipment contamination, simply because they are used so extensively in pre-preparation procedures. This is why some managers choose color-coded cutting boards. At a minimum, if a cutting board is reserved only for meat or only for fresh produce, the risk is reduced. However, all food contact surfaces are at play. This includes cutting boards, knives, countertops, blenders, mixers, utensils, storage containers, serving pans, and even potholders and aprons. Needless to say, proper cleaning and sanitizing between processes are the key weapon against this kind of cross contamination.
It's important to focus on entire work areas, not just a bowl or a utensil. British researchers demonstrated that simple food preparation tasks like cracking an egg can contaminate work surfaces as far away as 40 cm (about 16 inches) with Salmonella. When eggs are mixed or whisked as part of a recipe, they said, "contamination of surfaces around the mixing bowl was a common occurrence." They also noted, "Once present on formica work surfaces, S. enteritidis survived well." Bacteria were still present after 24 hours.
Some systems also describe a third kind of contamination—from people to food. In the CDC and FDA research cited previously, this is the contributing factor named as personal hygiene. And this factor does indeed contribute to foodborne illness.
The facts are alarming. The FDA study on FBI risk factors indicates that "proper, adequate handwashing" was the food safety control most "out of compliance" with FDA Food Code standards. Only 36% of the items that related to handwashing passed the audit. Among retail meat departments, the number dipped to 18%.
According to the FDA, "Handwashing reduces the spread of pathogenic microorganisms that are transmitted through food." The hands of food employees can be colonized with microorganisms such as Staphylococcus aureus or contaminated with organisms from human fecal material, such as Norovirus, Shigella spp., hepatitis A virus, E. coli O157:H7, or Salmonella Typhi, or contaminated from raw animal foods, with E. coli O157:H7 and Salmonella spp. These and other pathogenic microorganisms can get on the hands from a number of sources and then move from hands to food during preparation and service.
"An infected food employee and/or food employees with unclean hands, and exposed portions of arms or fingernails, can contaminate food. If a consumer eats contaminated food, foodborne illness may result."
While reasons, triggers, and procedures for handwashing are well known, compliance is an ongoing concern in both foodservice and healthcare industries. As reported in Cracking Edge newsletter, compliance with handwashing protocols in hospitals stands at less than 50 percent. Typical handwashing messages tell healthcare workers to wash their hands to avoid illness. But many healthcare workers are better motivated by messages that focus on patients, according to recent research, They suggest that routinely refreshing messages may improve compliance, too. Example: "Did you wash your hands? What if your mother was the next patient you saw?"
The 2009 FDA Report provides highly actionable information for any foodservice manager.
Using the targeted contributing factors and Food Code standards as a guide, researchers actually inspected 850 foodservice operations around the nation and directly measured compliance with best practices. They included a range of foodservice segments—hospitals, nursing homes, elementary schools, fast food restaurants, full service restaurants, and departments of retail food stores.
The study was designed to:
Researchers concluded, "Improper cleaning and sanitizing of food-contact surfaces before use was the item most commonly observed to be Out of Compliance in eight out of the nine facility types. Percent Out of Compliance values for this data item ranged from 18% in seafood departments to 64% in full service restaurants." Take a look at the FDA summary graphs below to see details for hospitals, nursing homes, fast food, and full-service restaurants.
The FDA researchers used five audit points derived from the FDA Food Code. These are targeted takeaway points for foodservice operators as well.
According to Colin Caywood, writing in Food Safety News, the self-service model of buffet dining "practically invites… cross contamination issues." This is because patrons are now practicing food service, but without the requisite training in foodservice sanitation.
Caywood cites examples of FBI outbreaks that traced back to buffet dining. One involved E. coli bacteria in Minnesota, linked to a Chinese buffet. Victims suffered severe infection and had to be hospitalized.
Another involved Salmonella Heidelberg at a buffet restaurant in North Carolina. Not one, but three meat entrees tested positive for the bacteria. Two employees were infected as well. Researchers could not determine whether the employees were sources or victims of a pathogen spread through the buffet.
Yet another case Caywood cites involved the breakfast buffet of a hotel in Colorado. Multiple groups of guests (and staff) became ill with Shigellosis.
Caywood emphasizes controlling risk factors such as temperature control and protecting food from contamination.
A study conducted by Benjamin Chapman and colleagues at North Carolina State University collected actual video footage of employees' foodservice sanitation practices in eight commercial kitchens.
As reported by the University, "Chapman's study found approximately one cross-contamination event per food handler per hour. In other words, the average kitchen worker committed eight cross-contamination errors, which have the potential to lead to illnesses, in the course of the typical eight-hour shift."
Chapman also found that the rate of error in personal hygiene and cross contamination increased dramatically during peak meal times.
"The prevalence of cross contamination is a hidden problem for food service, as food handlers acting in a multi-user environment may not see themselves as part of a team. Many of the recorded indirect cross contamination events occurred when multiple food handlers used common food contact surfaces, utensils, or equipment."
Chapman and colleagues have been testing interventions for improving food-safe practices.
The concept of cross contamination has taken on new meaning in light of the Food Allergen Labeling and Consumer Protection Act of 2004, which took effect in 2006.
It's estimated that more than 15 million Americans (4% of the population) have one or more food allergies, which are responsible for 30,000 emergency room visits and 150 deaths in the US each year.
Accordingly, the 2017 FDA Food Code offers guidance regarding food allergies. The "person in charge" at a foodservice establishment is now accountable for being able to identify common food allergens and recognize symptoms of an allergic response to food. Common food allergens, those most frequently involved in serious allergic reactions, are: milk, eggs, fish (e.g. bass, flounder, cod), shellfish (e.g. crab, lobster, shrimp), tree nuts (e.g. almonds, walnuts, pecans), peanuts, wheat, and soybeans. Find out more about food allergens in our free program, Allergy Awareness.
For individuals who are highly susceptible to allergic reactions, cross contamination is a critical issue. Controls extend beyond simply choosing (or avoiding) foods on a menu. Cross contamination of foods and/or work surfaces with allergens from other foods can trigger a life-or-death response. Says the FDA in its Food Code Annex, "The person in charge establishes an important barrier to food contamination."
The Wisconsin Department of Public Instruction provides these guidelines for preventing cross contamination with food allergens:
Food storage is one of the steps in the flow of food where food is subject to cross contamination. Here are some tips for preventing cross contamination from the National Food Service Management Institute.
One of the most crucial food-safe procedures in a foodservice operation is to begin each process with clean, sanitized work surfaces and equipment.
It takes more time to thoroughly sanitize work surfaces and equipment adequately than it does to use one item to wipe down everything. It is up to the foodservice manager to practice what the FDA Food Code calls "active managerial control" to implement practices, train team members, monitor compliance, and coach employees in actions that protect customers from FBI.
The National Food Service Management Institute offers these additional tips for preventing cross contamination during preparation.
NSF International identifies restaurant trays as one of the four "germiest items in public places." (The other three are: public park sandbox, school musical instrument, and theater video controller.) This research highlights the attention required for controlling the transfer of pathogens.
Besides routinely washing and sanitizing trays, try these tips for preventing contamination during transportation and service:
The principle of preventing cross contamination applies in home kitchens, too.
Consumer education can include messages that closely parallel those of foodservice. The USDA, in its fact sheet, "Be Smart. Keep Food Apart," offers tips for consumers that address all steps in the flow of food.
David L. Williams and colleagues, reporting in Food Protection Trends, determined that a growing consumer trend—reusable grocery bags—presents a cross contamination risk. The researchers found that about half of bags were contaminated with coliform bacteria. Coliform bacteria, a general category identifying bacteria that are common in feces, are used as a marker of biological contamination. E. coli is one example of a coliform bacteria, and in fact, 8% of the bags were contaminated with E. coli. Fortunately, there is a simple solution: washing the bags on a regular basis.
NSF has documented a number of studies about where pathogens collect in both public and home environments. In their most recent study of home kitchens, they flagged the six “germiest” items containing foodborne pathogens as follows:
They also said that 100% of home kitchen items tested contained yeast and mold “at concerning levels.”
After the first NSF "Germiest Places" report, microbiology expert, Charles Gerba, PhD of the University of Arizona, was quoted by Philly.com as saying, "You'd be better off eating a carrot stick that fell in your toilet than one that fell in your sink." He has also pointed out that cutting boards used for raw meat can carry 200 times more bacteria than a toilet seat. (Consumer Reports, March 2012).
Consumer advice offered by NSF includes:
Researchers at Kansas State University revealed that cloth towels are also a source of cross contamination. Even for towels that had been washed, pathogens such as Salmonella grew on them overnight. Cell phones, too, proved to be reservoirs of bacteria. This is important because many consumers use a mobile device in the kitchen when preparing food.
Researchers find towels to be a top source of cross contamination within the kitchen.
Here are some key points to keep in mind:
We invite you to explore the food safety resources listed on slide 18 to learn more about food safety.
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Michael Foods, Inc.