The role of hands in cross-contamination of kitchen surfaces during meal preparation

Background: Foodborne pathogen transmission during food preparation is a common occurrence, and cross-contamination can be a contributing factor. Behaviors that lead to cross-contamination during meal preparation have not been well characterized. The study objective was to determine how hands and food handling behaviors (with a focus on handwashing and touch-based events) affect the risk of cross-contamination of kitchen surfaces and foods during meal preparation. Methods: Data from a prior study in which participants were observed preparing turkey burgers inoculated with bacteriophage MS2 and a salad provided the data for analysis. Cross-contamination was assessed using environmental sampling data. Behavioral coding was performed for handwashing and touch-based behaviors. Cross-contamination risk was defined as the likelihood (number of contaminated surfaces) and degree (contaminant concentration) of MS2 on surfaces. Statistical analyses were performed in R, SPSS, and SigmaPlot. Results: The significantly reduced risk of cross-contamination (P.ß<.ß.0001) was observed for participants who attempted handwashing or completed more handwashing steps. Scrubbing hands for 5.ßseconds, on average, reduced the risk of cross-contamination (P.ß<.ß.05). Cross-contamination regression models created using the most significant predictor variables showed that increased handwashing attempts, completion of more handwashing steps, and average scrub times>5.ßseconds all decreased the risk of cross-contamination (P.ß<.ß.05). Conclusions: This analysis can be used in future risk assessment modeling and for informing education and outreach to reduce pathogen transmission during food preparation.