Environmental microbial hazards in food distribution centers


In order to address a knowledge gap regarding environmental microbial hazards in distribution centers, we are conducting a swab-a-thon for Listeria spp. concurrently with detailed management interviews in order to identify similarities and differences in facility designs, sanitation protocols, equipment characteristics, etc. that may contribute to Listeria spp. contamination in produce.


Food service distribution centers (DCs) have come under increased food safety scrutiny in recent years due in part to the passing of the Food Safety Modernization Act and specifically, the Preventive Controls for Human Foods (PCHF) Rule. While the majority of products passing through food DCs are fully sealed, fresh produce is often not sealed due to quality concerns related to continued respiration postharvest (Becker and Fricke 1996). For this reason, DCs need an environmental monitoring program as a part of their environmental or sanitation preventive controls, but insufficient data is available to determine if a) environmental pathogens are prevalent in DCs and b) if present, how likely these pathogens are to contaminate unsealed, fresh produce.


The data gap regarding Listeria spp. prevalence is currently being addressed via the 2020 CPS funded project “Environmental microbial risks associated with vented produce in distribution centers.” The team is collecting non-food contact, environmental samples in approximately 25 DCs throughout the United States to determine if specific DC profiles increase or decrease the likelihood of harborage of Listeria monocytogenes, using Listeria spp. as an indicator; this is done by concurrently collecting cleaning SSOPS, DC features, product types, relative humidity/temperature and other practices or characteristics that may drive microbial populations during each sampling visit. To date, the survey has identified potential harborage sites predominantly on floors or items that contact floors, including floor cracks, seams or patches as well as cleaning tools like dust mops and squeegees. Additionally, an unsealed wooden tabletop in the shipping area of one DC was positive for Listeria spp.


This research is actively providing food service and grocery distribution centers, including retailers with guidance to assist in hazard analysis and risk mitigation practices within facilities. This includes the identification of high or low risk practices or factors inherent to the distribution center environment.

State Issue

Food Safety and Quality


  • Year: 2020
  • Geographic Scope: National
  • County: Clarke
  • Location: College Station, Athens
  • Program Areas:
    • Agriculture & Natural Resources


    Dunn, Laurel L


Non-CAES Collaborator(s)

  • Benjamin Chapman, North Carolina State University
  • Laura K. Strawn, Virginia Tech
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