U.S. flag An official website of the United States government
  1. Home
  2. Food
  3. Compliance & Enforcement (Food)
  4. Sampling to Protect the Food Supply
  5. Environmental Sampling
  1. Sampling to Protect the Food Supply

Environmental Sampling


Environmental Sampling at a Facility


This page is intended to serve as an overview. Additional information on environmental sampling is available in the FDA’s Investigations Operations Manual (Chapter 4).

During inspections, the FDA may collect samples from the environment in a building where foods are produced (a manufacturing plant or a commercial kitchen, for instance) to determine whether that environment contains harmful bacteria, such as Salmonella spp. or Listeria monocytogenes. FDA investigators use sterile sponges or swabs to collect these samples from both food contact surfaces (e.g., slicers, mixers, utensils or conveyors) and non-food contact surfaces (e.g., floors, drains, carts or equipment housing). This type of sampling is called “Environmental Sampling,” and it is important because environmental contamination – absent proper monitoring and controls – may contribute to contamination of finished product.

Why the FDA May Collect Environmental Samples in an Establishment

The FDA may conduct environmental sampling of an establishment for any of the following reasons:

‘For Cause’

  • To further investigate an establishment with an indication of a potential serious public health risk where microbial hazards may be present and contributing to contamination of food. A history of concern may include, for example, prior suspected or confirmed linkage to human illness, recalled or seized contaminated product, or prior detection of environmental pathogens without verification that the establishment implemented proper corrective actions;
  • Inspectional observations that warrant the collection of samples for microbiological analyses, such as insanitary conditions (e.g., evidence of intrusion by birds or rodents, or dirty food contact surfaces of equipment), or an establishment’s failure to implement an effective environmental monitoring plan, as required; or
  • As follow-up to the detection of a pathogen in a product sample (through testing by the FDA, or a state or private laboratory, or as reported to the Reportable Food Registry).

Commodity-Based Assignments

The FDA initiates commodity-based assignments to gain insights into how widespread certain harmful bacteria may be in the manufacturing environment(s) across an industry, to assess conditions and practices, and to gauge compliance with food safety regulations. The FDA may use the findings from such assignments to inform guidance to industry or to conduct further risk-focused targeted sampling, in addition to responding immediately to any food-safety hazards identified.

Risk-Based Prioritization

The FDA has developed a process for considering establishment-specific potential risk to the public health. Establishments may be identified for environmental sampling using this process, which employs criteria related to food-hazard pairs (e.g., frequency of outbreaks associated with a food, likelihood of contamination, bacterial growth potential, and food consumption pattern), and establishment-specific compliance history.

What to Expect When the FDA Collects Samples

See the FDA’s Sampling to Protect the Food Supply page.

Findings that May Elicit Regulatory Follow-up

While all regulatory actions are considered on a case-by-case assessment of the evidence and findings, the following environmental sampling results are examples of patterns that could lead to FDA consideration of regulatory follow-up.

  • A finding of a pathogen in an environmental sample collected from a food contact surface located post ‘kill step’ or where bacterial contamination is not subsequently controlled. Such a finding indicates a significant risk that a food is or may have been contaminated and that a recall of the affected food may be warranted to protect consumers.
  • A finding of a pathogen in environmental samples collected from non-food contact surfaces coupled with other indications of insanitary conditions and/or failure to adhere to good manufacturing practices.
  • A genetic match established by whole genome sequencing that connects a bacterial strain found in an environmental sample and a bacterial strain from an ill person. When supported by product traceback and/or epidemiological evidence (e.g., a patient food history), this is another scenario where a recall of the affected food may be warranted to protect consumers.
  • A genetic match established by whole genome sequencing that connects environmental isolates obtained on two separate occasions from the same establishment, indicating that a facility may have a potential harborage of a pathogen in a food processing environment and/or that a facility is not adequately controlling environmental pathogens.
  • A genetic match established by whole genome sequencing that connects an environmental isolate and a food isolate from the same establishment. Once again, this is a scenario where a recall of the affected food may be warranted to protect consumers, and food likely to be affected in a similar manner must also be assessed.

How to Prevent Contamination in Processing Environments

The Preventive Controls for Human Food rule is designed to protect consumers by keeping harmful bacteria from contaminating processing environments and, ultimately, the food we eat. The rule requires that an establishment’s operators take steps to prevent contamination, including from pathogens in the environment, and verify that hazards are being controlled. Environmental monitoring and product testing are examples of steps they may take to verify control of microbial hazards.

The FDA has published a detailed draft guidance for industry on how to control Listeria monocytogenes, a pathogen that is frequently associated with contamination of ready-to-eat foods from the environment.

The information below summarizes some of the key actions that food processors can take to prevent environmental pathogens in their establishments.

  • Applying good manufacturing practices to ensure appropriate personnel practices, sanitary design of the establishment and equipment, and sanitary operations.
  • Evaluating whether preventive controls are needed for hazards, including for environmental pathogens, and, if so, developing and implementing strategies to control such pathogens.
  • Monitoring and verifying the performance of implemented controls, particularly sanitation controls, including verifying the controls by environmental monitoring when appropriate, initiating prompt corrective action when problems arise, and maintaining records of required monitoring and verification activities.
  • Ensuring employees have the necessary training or experience for their assigned duties, as well as appropriate training in food hygiene and food safety.

The FDA anticipates that establishments featuring robust environmental monitoring programs will occasionally detect environmental pathogens, and how an establishment responds to such findings is critical. The key objectives are to find the pathogens, if present, through sanitation monitoring programs; to focus on where, when and why the pathogens emerged; and then to implement effective strategies to eliminate them and prevent their recurrence. The FDA has seen many examples of establishments implementing controls that effectively prevent and control environmental pathogens and facilitate the production of safe and wholesome food. Depending on the circumstances, an establishment’s operators may need to conduct a root cause analysis and/or take prompt and aggressive corrective action to address contamination and prevent pathogens from becoming established in a plant environment. The FDA will assess the adequacy of an establishment’s corrective actions (following an establishment’s detection of environmental pathogens), as well as its implementing of food safety regulations, in accordance with the Federal Food Drug and Cosmetic Act, and consistent with the agency’s mission to protect consumers.

Environmental Sampling Assignment Results

Back to Top