Cross-contamination is an important concept to understand in the field of Food Safety management. It can be loosely defined as “the physical movement or transfer of harmful pathogens [or allergens, sometimes further defined as cross contact] from one person, object or place to another.” 1 While this definition is broad, it illustrates the variety of ways pathogenic bacteria, viruses, and even allergens can move around within a retail and foodservice establishment and onto ready-to-eat foods. One frequent way is through cross-contamination of surfaces. In this article, we discuss how surfaces can become contaminated with pathogens in an establishment; the risks this type of cross-contamination can pose to guests, consumers, and businesses; and offer best practices and advice for minimizing the risk of surface cross-contamination in a food handling setting. Hands play an important role in the cross-contamination of foods as well, and even when employees wear gloves, gloved hands can lead to cross-contamination of surfaces and foods when gloves are not used properly. 2
Contaminated Surfaces – Understanding the Risks
According to the CDC, 3 five major risk factors in the retail and foodservice industries contribute to foodborne illnesses:
- Poor personal hygiene
- Improper food holding/time and temperature
- Protecting equipment from contamination
- Inadequate cooking
- Food obtained from unsafe sources
While all five risk factors can play a role in contamination of surfaces, contaminated equipment is the most obvious risk factor linked to contaminated surfaces. Just how often are contaminated surfaces and equipment observed in food establishments? According to the FDA, in a multi-year study of 821 restaurants, the percentage of full-service restaurants with out of compliance violations for having contaminated equipment was over 82%! 4 Clearly, the entire food industry has room to improve with regards to controlling this foodborne illness risk factor.
So far, we have seen just how prevalent an issue contaminated surfaces are in food handling settings, but what pathogens can contaminate these surfaces? Short answer – pretty much all of the known foodborne disease-causing pathogens. Norovirus, a virus that causes the majority of foodborne illness from foodservice establishments, can spread from restroom door handles to a food employee via touching, especially if the handle is not disinfected properly. Listeria monocytogenes, one of the most severe bacterial foodborne illnesses, can find its way into grocery deli floor drains through contaminated incoming food and on cleaning tools and processing equipment. Below are just a few examples that highlight the broad diversity of pathogens associated with surface cross-contamination.
Minimizing the Risks
There is no denying it – contaminated surfaces and equipment can serve as sources of foodborne illness outbreaks by cross-contaminating food. Therefore, how can we best minimize the risk of this happening? The best practices for controlling surface contaminants generally fall under two categories: how to keep contaminants out of a facility and how to minimize contaminants from spreading once they are within a facility. Here are several best practices for reducing the risk of surfaces becoming contaminated with dangerous pathogens
Supplier Verification – Controlling foodborne pathogen risks within an establishment begins with having a supplier food safety management program in place, either by developing your own or by sourcing food and ingredients from trusted distributors. Many raw ingredients (e.g., raw ground meats, fish, poultry, produce) can harbor most of the foodborne pathogens that cause foodborne disease outbreaks, and once they enter the food establishment, the risk of cross-contamination increases as employees handle these ingredients (during the multiple food preparation processes). When a business can work with its suppliers to reduce the numbers of these pathogens on raw foods (e.g., checking to ensure ground beef does not have E. coli O157 and other STEC pathogens before it is received), it reduces the likelihood that employees will contaminate food contact and non-food contact surfaces with these pathogens.
Employee and Guest Controls – Raw ingredients and food are not the only potential source of incoming pathogens. People can be a source of pathogen spread, especially foodborne viruses like norovirus and hepatitis A virus. For food employees, it is critical to have policies in place that prevent sick individuals from reporting to work. Not only is this required by the FDA Food Code, 5 but it has been shown to be extremely effective in preventing foodborne disease outbreaks. A study by FDA researchers showed that keeping employees ill with norovirus out of work was the most effective control measure for reducing the risk of a norovirus outbreak in a foodservice establishment. 5 For norovirus infections, food handlers should be excluded from work until they are symptom-free for 24 (minimum) to 48 (preferred) hours.
In addition to employees, guests can also be a source of incoming pathogens. Obviously, it is difficult to completely prevent sick guests from coming into your establishment (just as it is difficult to exclude all sick employees if they don’t report illness during screening), but there are best practices you can adopt to help control this risk. One way is to perform frequent restroom and high touchpoint disinfection, preferably multiple times per shift. Sick guests and employees may shed high amounts of pathogens in their vomit and stool, making the restroom a high-risk area for pathogen spread via surface contamination. In fact, the previously mentioned FDA study also found that keeping restroom touchpoints free from norovirus (door handles, faucet knobs, etc.) was a highly effective way of controlling norovirus outbreaks in a restaurant. 6 Keeping restrooms clean and well stocked with hand hygiene supplies such as soap and paper towels will also encourage guests and patrons to wash hands after visiting the restroom, which can minimize spread of pathogens via touch. Alcohol-based hand sanitizers placed at either the entrance or in the lobby have also become more prevalent during the COVID-19 pandemic and help bring an extra hand hygiene opportunity for guests as they enter an establishment.
Assess your Chemical Program – The chemical management program in your establishment is an important part of your food safety management program. It is important to periodically assess your program to ensure its meeting your needs. Reviewing sanitizer and disinfectant kill claims and required contact times is a good first step. Are your products effective for the pathogens of risk in your establishment? (Tip: most food contact surface sanitizers are not effective against norovirus). Is it realistically easy for employees to comply with the contact times indicated? Are there hazards associated with the use of the chemical (i.e., mixing)? Is dilution required? The answers to these questions (and others) can be found by reviewing the product’s federally registered EPA accepted label. 7
Maintain Separation Between Raw and Ready-to-Eat Foods – As mentioned before, raw food and ingredients can be an incoming source of pathogens in an establishment. Because of this, it is important to prevent surfaces and utensils used to prepare raw foods from contacting ready-to-eat foods, at least not until they have been properly washed, rinsed, and sanitized. One well-known example of a raw food at risk for cross-contamination is raw chicken, which is known to carry many bacterial pathogens, including Salmonella and Campylobacter. In one study, observations of restaurants handling raw poultry showed that 40% of managers did not separate raw vs. ready-to-eat cutting boards for chicken preparation. A best practice would be to keep dedicated surfaces (including cutting boards), equipment, and utensils for handling raw poultry only. Better yet, a color-coding system to make this separation easier for employees to execute would be even more ideal (see: https://www.food-safety.com/articles/6258-the-need-for-a-glove-use-management-system-in-retail-foodservice ). The CDC study also showed that 30% of managers were not observed washing and rinsing prior to sanitizing the cutting boards. 8 Without a proper wash and rinsing step prior to sanitizing, harmful pathogens can remain on the surface, as food debris left over from lack of washing can negatively impact the sanitizer efficacy.
Touchpoint Disinfection (Restrooms and Atypical Surfaces) – As mentioned previously, touchpoint disinfection in restrooms is a known way to reduce risk of norovirus within an establishment. In addition, there are other surfaces that should require, at minimum, daily disinfection. Tables, menu items, condiment stands, and touch screen ordering kiosks are just a few additional examples of surfaces that require attention during the day, as they may become contaminated with pathogens that spread disease. 9
Closing Thoughts
Because of multiple risk variables it is important to remember that there’s no “silver bullet” for controlling cross-contamination of food via surfaces. The best way to reduce risk is to ensure every aspect of your food safety management program is being executed and can be observed via monitoring. If one element of the program breaks down, it can substantially increase the risk of cross-contamination. Therefore, it is imperative to periodically assess every aspect of your food safety management program and always strive for continuous improvement. By following the above best practices, building the best food safety management program you possibly can, and placing food safety at top of mind for all employees via training and monitoring, cross-contamination risks associated with surfaces can be effectively controlled.
For more information, be sure to check out our upcoming webinar “On the Surface? Deep Links Between Cross-Contamination and Surfaces,” as part of the PURELL Table Talks series.