Although many people know that washing poultry is not a good way of preventing foodborne illness, a recent study found that it might be more dangerous than most realize because it can lead to dangerous cross contamination.

The study from North Carolina State University on the impact of poultry washing on kitchen contamination found that 25 percent of participants contaminated salad with raw poultry.

The study, “Observational Study of the Impact of a Food Safety Intervention on Consumer Poultry Washing,” was published in the Journal of Food Protection. The corresponding author of the study and an extension associate at North Carolina State University, Ellen Shumaker, explained that they wanted to know the effect an educational intervention would have on getting people to stop washing poultry before cooking, and also what effect any resulting change in behavior might have on reducing contamination in the kitchen.

They also found that high levels of the bacteria were detected in the sink and on the salad lettuce. “We think the salad contamination stems from people doing a poor job of washing their hands after handling the raw chicken, and/or doing a poor job of sanitizing the sink and surrounding surfaces before rinsing or handling the salad,” Shumaker said.

The researchers suggest that messaging should focus on hand washing and cleaning and sanitizing surfaces.

“Regardless of whether people washed their chicken, the kitchen sinks became contaminated by the raw chicken, while there was relatively little contamination of nearby counters,” Shumaker said. “This was a little surprising, since the conventional wisdom had been that the risk associated with washing chicken was because water would splash off of the chicken and contaminate surrounding surfaces. Instead, the sink itself was becoming contaminated, even when the chicken wasn’t being washed.”

Shumaker says that this study demonstrates the need to focus on preventing contamination of sinks and emphasizing the importance of hand-washing and cleaning and sanitizing surfaces.

The Study’s Methods

  • Treatment group participants received three e-mail messages containing information that the U.S. Department of Agriculture has used on social media sites related to poultry preparation, including advising against washing raw chicken. 
  • Participants were observed cooking chicken thighs that has been inoculated with traceable nonpathogenic Escherichia coli strain DH5α and preparing a salad to determine whether they washed the chicken and the extent of cross-contamination to the salad and areas of the kitchen. 
  • After meal preparation, participants responded to an interview about food handling behaviors, including questions about the intervention for treatment group participants. Three hundred people participated in the study — 158 control and 142 treatment. 

Study’s Findings

  • The intervention effectively encouraged participants not to wash chicken before cooking; 93 percent of treatment group participants did not wash the chicken. Only 39 percent of control group participants did not wash the chicken.
  • The high levels of E. coli DH5α detected in the sink and on the salad lettuce suggest that microbes transferred to the sink from the chicken, packaging, or contaminated hands are a larger cause for concern than is splashing contaminated chicken fluids onto the counter. 
  • Among chicken washers, 26 percent and 30 percent of the lettuce from the prepared salad was contaminated for the control and treatment groups, respectively.
  • For non-washers, 31 percent  and 15 percent of the lettuce was contaminated for the control and treatment groups, respectively. Hand-facilitated cross-contamination is suspected to be a factor in explaining this resulting lettuce cross-contamination.

The full study can be found here.

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