Conducting an Environmental Investigation

Table of Contents

Introduction

An environmental investigation is an essential component of a suspected outbreak of foodborne illness. Epidemiologists, laboratorians, and environmental health professionals work collaboratively to manage an outbreak of foodborne illness.  Illnesses may be avoided if potentially contaminated foods are promptly identified and removed from sale or service to the public, and poor food handling practices are corrected. Other reasons for initiating an environmental investigation include government responsibility, consumer expectation, and vindication of innocent establishments. The objective of the environmental investigation is to:

  • Identify the reason for, or source of contamination
  • Initiate corrective actions, if necessary, to eliminate contaminated foods
  • Identify and address issues such as poor food handling that may result in contaminated foods, and to assure that it will not occur again.

Although circumstances of each outbreak may determine the progression of an environmental investigation, certain basic actions must be completed whenever an environmental investigation is initiated.  There are additional evaluation steps conducted in an outbreak situation that would not be included in a routine inspection of an establishment.     

It is essential to maintain interagency collaboration in the investigation of outbreaks of foodborne illness.  Communication of the results of each agency’s investigation, including those of the Department of Inspections and Appeals (DIA), Iowa Department Public Health (IDPH),  and University Hygienic Laboratory (UHL) is vital to ensuring a thorough multifaceted investigation.

Key factors during an Environmental Outbreak Investigation

Unlike routine inspections, an environmental investigation of a foodborne disease outbreak may take several hours and it involves the evaluation of all suspected processes. Factors in the evaluation include:

  • An environmental investigation initiated within 24 hours of receipt of an outbreak notification
  • A review of the previous routine inspection reports of the implicated food establishment
  • An acquaintance with the inspection equipment and forms to conduct a complete investigation
  • An onsite inspection
  • Conduct a HACCP risk assessment
  • Participates on the multi-disciplinary outbreak investigation team

The basis of an environmental investigation is the on-site investigation.  On-site inspections of retail food establishments are used to monitor/determine compliance with the provisions of the Iowa Food Code, an adaptation of the FDA Model Food Code.  Environmental health professionals with the Iowa Department of Inspections and Appeals (DIA), or a contracting municipality, are responsible for conducting the inspections in Iowa.  Following completion, environmental health professionals consult with the food-establishment operators, commonly referred to as the Person In Charge (PIC), and when problems are identified, to initiate appropriate corrective actions to reduce the risk of foodborne illness.

The Iowa Food Code provides a detailed description of the methods and processes necessary to ensure food safety at a retail food establishment.  The Foodborne Outbreak Investigation Manuall does not duplicate those provisions but attempts to provide a functional understanding of the types of code requirements environmental health professionals review in such an inspection.  This section acknowledges that environmental health professionals have a specialized knowledge of the code and should be partners with public health in epidemiological investigation of outbreaks of foodborne illness involving food establishments.

On-site Inspection Components:

  • Food - Examples: source, labeling, condition, possible means of contamination and time/temperature factors (cooking, cooling, reheating, etc.).
  • Personnel - Examples: food-handler illness records, use of hand washing facilities, and condition of the skin of the hands, and procedures for handling ready to eat foods.
  • Equipment, utensils and linens - Examples: characteristics, cleaning, storage and thermometer availability.
  • Water, plumbing and waste - Examples: source, availability of hand washing facilities, presence of backflow prevention device and removal of sewage/refuse.
  • Physical facilities - Examples: condition of, and ability to clean, interior surfaces, presence of protective shielding over light bulbs and availability of hand-washing soap.
  • Poisonous or toxic materials - Examples: chemical labeling, storage and approval for use in food establishment.
  • Compliance and enforcement - Examples: preventing health hazards, Hazard Analysis Critical Control Point (HACCP) plan development and permit issuance. The code knowledge of the person in charge and training of employees on food safety should also be examined.

Once the inspection has been completed, environmental health professionals produce a report detailing code violations and other findings.  The report is then reviewed with the establishment operator/person in charge, violations that can be corrected at that time are corrected and other corrective actions discussed.  Review of the inspection allows the inspector to provide education and answer any questions the operator may have on process improvements or corrective actions needed to be in compliance with the code. 

In addition to conducting the evaluations and education steps with the establishment the environmental health professional participates with the outbreak management team reviewing epidemiological and laboratory results.  It is essential to maintain interagency collaboration in the investigation of outbreaks of foodborne illness.  Communication of the results of each agency’s investigation, including those of the DIA, IDPH and University Hygienic Laboratory is vital to ensuring a thorough multifaceted investigation.

Steps of an Environmental Outbreak Investigation

1.  Notification of partners

Prior to initiating an environmental outbreak investigation, an investigation team should be formed.  This includes an epidemiologist, a laboratory official, and an environmental health professional.  Then as a team preliminary discussions should include what is known, what are the specific facts, and thus what to target or look for during the on-site inspection.  Once the investigation begins the team will maintain contact with others involved through out the investigation to modify actions as indicated.

Department of Inspection and Appeals (DIA) Notification

Upon receipt of a request to perform an environmental investigation of an establishment potentially involved in a foodborne outbreak, the environmental health professionals should ensure that the DIA has been made aware of the situation.  This notification ensures that DIA is prepared to address any questions from people involved in the outbreak, the media and other organizations.

2.  Review of past inspections

Conducting a brief review of the findings of past inspections allows the environmental health professionals to determine whether an establishment has been cited for repeated critical violations, identify equipment that may have been cited for improper holding or cooling temperatures, and review any complaints about the establishment.  The review provides environmental health professionals with a history of the establishment and allows them to identify potential violations to be particularly aware of at the start of an investigation.

3.  Interviewing the Person In Charge

The person in charge (PIC) is responsible for the operation of the facility at the time the environmental health professionals arrives.  The interview should identify:

  • standard operating procedures for preparing the suspect food(s),
  • any differences in preparation of the suspect food(s)
  • whether any staff have been ill recently, left work sick the day the suspect food(s) were prepared or served, or called in sick over the following few days, and
  • whether the establishment has received any other complaints.

The food(s) suspected of being the vehicle for illness are termed the “suspect food(s).”  Suspect food(s) are generally determined through the findings of the epidemiological investigation.  However during the initial onsite inspection an intermediate step should be taken to look at preparation of high risk foods. Typically, the environmental investigation will begin before identification of suspect food(s).  In this situation, the size of the menu may determine whether information on suspect food(s) is collected by the environmental health professionalsduring this visit.

When there is a limited menu, such as at a catered event, it’s best to obtain information on procedures used to prepare each item.  When the establishment prepares a large number of items, detailed information on preparation of suspect food(s) may have to be obtained on a follow-up visit after the information is collected through the epidemiologic investigation. In this case, the environmental health professionals should obtain a menu.  The menu, or any menu from an event in question, should be provided to epidemiologic investigators to help develop a questionnaire.  The information obtained through questionnaires is the basis for identification of suspect food(s).  In addition assurance should be given to the establishment the investigation is not looking to “blame” and any epidemiological information collected will not be shared.

3.  Interviewing staff

Interviews of staff members of food establishments on their activities during the exposure period of people who are ill are important.  They allow environmental health professionals to discuss in-depth the actions of staff members in that period, determine illness status around the time of the exposure and identify any departure in preparation of suspect food(s) from the standard operating procedures described by the PIC.  Interviews should be conducted confidentially without the presence of the PIC.  When necessary, they can be conducted by phone, after-hours, to ensure candid responses from staff.  The interviews should identify:

  • Which staff members helped prepare or serve the suspect food(s),
  • Whether any of them had been ill recently or were ill during the period the food was prepared or served,
  • Whether they can identify any other ill staff members during the time the food was prepared or served,
  • Whether staff members have infected sores/wounds,
  • Whether good hand-washing procedures were followed, and
  • Procedures by staff members in preparing suspect food(s) on the date in question

4.  Facilitating enteric collections

When the PIC and staff interviews have revealed employee illness, obtaining stool specimens from employees who were ill during the time the suspect food(s) were prepared or served or shortly after may be indicated.  When that occurs, access to and distribution of enteric kits, instructions for collection, handling and submission of stool for testing must be organized.  Coordinating enteric collection with the entity conducting the epidemiologic investigation may be beneficial.  People responsible for the epidemiologic investigation typically have enteric kits available and may be working with ill patrons to obtain stool specimens. Such coordination can ease any problems of submission and transport to the University of Iowa Hygienic Laboratory.  When ill employees are identified and still capable of spreading the pathogen, the PIC should be notified and ill employees excluded from work, in accordance with Chapter 2 of the Iowa Food Code.

5.  Conducting a HACCP risk assessment on suspect/implicated food(s)

Hazard Analysis Critical Control Point (HACCP) is a science-based method for evaluating food handling to identify or prevent hazards which contribute to foodborne disease.  A trained environmental health professionals should conduct the HACCP assessment.  Information on conducting such an assessment is included in a subsequent section of this chapter.

6.  Prepare a flowchart of suspect/implicated food(s)

The HACCP risk assessment should be the basis for developing a flowchart for an organized representation of the procedures used by the facility to prepare the suspect food(s).  The flowchart should include:

  • The source of the food;
  • Ingredients used in preparing it;
  • How the food was prepared;
  • Who prepared/served it;
  • The period in which it was prepared,
  • The temperatures at which the food was held during and after preparation, and
  • Where it was kept following preparation.

A timeline for preparation of the food should be obtained. A record of the times and methods used when thawing, cooking, cooling, etc. is vital to identifying time and temperature abuses that could have contributed to the food contamination.

7.  Collect samples of suspect/implicated food(s)

First an environmental investigation should be initiated within 24 hours of receipt of an outbreak notification. Always identify and collect any leftover food during the on-site investigation so important samples will not be inadvertently discarded.  Which specimens to test can be decided later once information from the epidemiological investigation is available.

Collecting food samples allows laboratory personnel to test them for microorganisms or chemicals.  Any pathogens or chemicals identified can be correlated with the signs and symptoms of illness and findings of any specimens collected from ill people. The procedure for collecting a food specimens is:

  • Use pre-assembled food sample collection kit.
  • Label products clearly.
  • Fill out Chain of Custody Form; obtain signature of PIC on form.
  • Keep potentially hazardous foods cool for transport.  Place frozen ice packs, samples, and chain-of-custody form in cooler. Use bubble-wrap or newspaper to protect samples from contact with ice packs.
  • Samples should be packed to prevent breakage, spillage, or change in temperature.

Please refer to Chapter 9, Conducting a Laboratory Investigation, for guidance on the collection and transport of food samples.

8.  Conduct an inspection of the facility

A regular food-establishment inspection should be completed to determine compliance with the Iowa Food Code, as discussed earlier. 

9.  Corrective actions

  1. Request voluntary destruction of food(s) from unsafe sources or in unsound condition.
  2. Issue hold orders when necessary.
    • Use hold tags if needed.
    • Document that the food tagged should not be used, sold or moved from the facility or destroyed without a written release from the regulatory authority.
    • Specify the reason for hold order.
    • Identify the food, label information, container description, quantity, hold-tag number and location.
    • Provide information on Appeals Rights to the permit holder.
    • Provide notice of the regulatory authority’s right to order destruction of the food if a timely appeal request is not received.
    • Provide the name and contact information of the regulatory authority.
  3. Determine if the closure of establishment is necessary.
  4. Exclude or restrict from work ill food workers in accordance with the Iowa Food Code.
  5. Ensure that all critical violations that can be corrected at the time are corrected.
  6. Establish a time frame for the correction of other critical violations.
  7. Institute controls as soon as possible to prevent further illness.
  8. Determine how the review of corrections is to be conducted.
  9. Determine if a follow-up inspection is necessary to verify compliance.  

Conclusion

When investigating suspect foods which may have been contaminated prior to being received at the retail establishment, obtain as much product information as possible to identify the exact source, and remove contaminated products from distribution.  It may be necessary to work with federal agencies, such as USDA or FDA, to remove contaminated products from distribution.

Conducting a HACCP risk assessment of the implicated food is necessary to identify potential hazards or points of contamination and time/temperature abuse.  A report that reflects a HACCP-based investigation provides specific information to the food-establishment operator, complainant, board of health members, IDPH, DIA, lawyers, etc...

A HACCP risk assessment may require more than one contact with the food operator during site visits or telephone calls to obtain all the information necessary to assess the procedures.  Elements in the investigation may change and can require shifts of focus in suspect procedures.  Stay open-minded and patient. 

Findings may demonstrate how a food establishment is employing safe food handling procedures in preparing the suspect food.  Findings may also reveal critical control points in the preparation of the suspect food that were not safely done or monitored.  In this case, a HACCP risk assessment may identify faulty food handling that can be replaced with safe practices and procedures, helping to avert future occurrences of foodborne disease.