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

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.

 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.

The significantly reduced risk of cross-contamination (P < .0001) was observed for participants who attempted handwashing or completed more handwashing steps. Scrubbing hands for 5 seconds, on average, reduced the risk of cross-contamination (P < .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 seconds all decreased the risk of cross-contamination (P < .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.

Kirchner M, Goulter RM, Bernstein C, Lavallee A, Schaffner D, Chapman B, Jaykus LA. The role of hands in cross-contamination of kitchen surfaces during meal preparation. American Journal of Infection Control. 2023 Nov 1;51(11):A44-57.  https://doi.org/10.1016/j.ajic.2023.04.162