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Issues: Food Safety

Produce Tracebacks

To help its members and industry understand the traceback process, PMA has prepared this overview. When a foodborne illness outbreak is linked to produce, quick resolution of the problem is essential from several perspectives:

• Public health is at risk and must be protected.
• Companies involved in the outbreak, or even peripherally linked to the outbreak face business disruptions until (and possibly even after) it is resolved.
• Public confidence in the produce supply can erode until definitive answers are reached and communicated.

A traceback investigation is initiated when: 1) epidemiologic evidence implicates a food product, and 2) hazard analysis shows that other contributing causes were not to blame (such as cross-contamination, ill food workers, or other sources of an infectious agent at the point of service).

Once an item has been linked to an outbreak of foodborne illness, a traceback works from the point of sale or service of the food backwards through the distribution chain to the source of the product. Through this process it may be possible to determine where contamination of the product occurred, correct any problems, and even recall suspect product that might remain in the distribution system.

A successful traceback depends on cooperation from every link in the distribution chain. Because an outbreak usually is identified long after the suspect product has been consumed or destroyed, it is likely that records will be the major tool in a traceback, rather than the product itself.

Understanding what public health officials look for in a traceback will help PMA members understand what role they may be expected to play and how they may prepare their companies through procedures and recordkeeping to assist in a traceback investigation.

The following is not a regulation; it is simply an explanation of how a traceback instigated by the U.S. Food and Drug Administration (FDA) may work. Members are not required to follow this document or implement any specific recommendations. But members may find this a useful tool for organizing their recordkeeping to be prepared to help public health officials in the unlikely event that a traceback is necessary.

Overview

A traceback's purpose is to determine and document the distribution and production chain for a product that has been implicated during an epidemiological investigation of foodborne illness. The FDA believes a traceback investigation involves good interviewing techniques, a complete records review, and timely reporting to meet its intended purpose.

FDA reports that fresh fruits and vegetables are extremely difficult to trace back because in many instances lot numbers and/or grower identifications are not used or recorded on receipts and/or shipping records. If a distributor cannot identify specific shipments and their source, FDA officials will use tools and interviewing techniques outlined in the FDA instructions to help identify possible shipment(s) involved in the outbreak.

Investigators initially visit the point-of-service (POS) establishment (i.e., where the product was sold or prepared) to determine when the product was purchased or prepared, and determine receiving, stock rotation, inventory, handling, and shipping procedures. Investigators collect records covering all suppliers and shipments of implicated product to the POS over the shelf life of the implicated product, i.e., the maximum number of days from the time of harvest that the product could still be realistically served or sold at the POS.

Data relating to distribution is charted and analyzed using a shipment delivery timeline to identify suspect shipments before proceeding with the next step of the investigation. A flow diagram provides a visual presentation of the distribution chain.

Following analysis at each distribution level, the FDA will visit and interview distributors who supplied suspect shipments of product. Distributor interviews, data collection, and analyses are repeated for each level of distribution until investigators identify the source of production. Traceback investigation reporting is required at each level for each firm involved in the investigation. When the traceback is complete, a final report is prepared on the traceback that contains:

• A complete timeline from POS back to the source
• A complete flow diagram illustrating shipment from the source to the POS
• A narrative outlining the decision-making process throughout the traceback investigation
• Identification of the producer(s) or grower(s)

Data Collection

If any of the suspect product still exists, samples will be taken for testing. It is also possible that, when the implicated product is not available, similar product from the same source may be sampled for testing.

A questionnaire is designed to help the FDA gather key information on each firm's handling, shipping, and receiving practices as well as information on shipments received from suppliers during the shelf life period of the implicated product. The FDA needs only obtain information covering the maximum shelf life of the product. For example, if an event resulting in an outbreak took place on March 27 and the product had a maximum shelf life of 15 days, regardless of the level of distribution, the earliest date that must be covered is March 12.

In addition to completing the questionnaire, investigators will ask to see copies of company records including shipment, receiving, and sales records. They will interview more than one employee at multiple levels of the organization (e.g., manager, warehouse worker, loader) to determine whether the standard operating procedures identified are actually being followed.

If it appears that the firm's lot identification system is reliable and can be used in place of performing a complete traceback analysis on shipments received and sold, investigators will collect the appropriate records and may be able to skip most sections of the questionnaire. The FDA will collect the following information at all levels of the traceback:

1. Product identifying information: label information, container type, size, color, grade, and lot codes, production or pull dates if available, and product origin
2. Product handling and storage practices: preparation, repackaging, and/or handling of the implicated product prior to service or sale, time and temperature parameters maintained during preparation delivery, storage, loading, etc., and on relevant unloading, storage, loading, or other pertinent conditions
3. Shipping and receiving practices:

• Delivery/receipt times: the approximate time and date of product receipt and preparation to narrow down shipments of potential interest
• Stock rotation practices: whether there is a standard operating procedure for stock rotation at the firm and whether it is, in fact, practiced
• Daily (or otherwise) stock inventory: documentation of the firm's inventory system, including its strengths and weaknesses, and what time of day the inventory is performed (inventory records are best kept for six months and are among the most helpful records in a traceback)
• Ordering practices: what level of depletion prompts the firm to order additional product, which may help reduce the number of suspect shipments

Investigators are instructed to collect sales/shipping records covering outgoing shipments of product to previously identified customers and sales/shipping records covering incoming shipments from suppliers for the shelf life period of the implicated product. Obtaining records covering shipment to a previously identified customer ensures that no shipments were missed during the traceback investigation at that customer's operation.

Investigators will seek to document:

• Invoice number, date, and quantities received
• Date received
• Name and address of shipper(s)
• Method of shipment, shipping record(s) numbers (airway or freight bill numbers), and dates
• Lotnumbers or lot codes received

For imported products, they will also collect:

• Importer's invoice, air bill/freight bill, and date of shipment
• Importer (broker) name/address with port of entry, if available
• Customs form 3461: Entry/Immediate Delivery (including customs entry number), plus (if available and not required) Customs form 7523: Entry and Manifest of Merchandise Free of Duty, and FDA form 701: Importers Entry Notice that may document day of entry

For processors or producers they will also seek to document:

• Dates of production
• Amount of product produced
• Production records
• Processing or production conditions that may contribute to product contamination
• Finished product and raw material samples, if available

Data Analysis

As investigators complete each level of the traceback, they will analyze all the information they have collected and identify all shipments that could be implicated in the outbreak.

They will use a timeline chart as an easy visual reference of the receipt dates of deliveries made to each level of distribution and inventories on any given date, if available. The timeline also illustrates historical use patterns.

Investigators will analyze data one distribution level at a time, plotting one distributor per line. They will use inventories, estimated turnover rates, stock rotation, and delivery times to identify suspect product shipments and to determine which distributors need to be visited to continue the traceback.

They will only exclude shipment or distributor investigations if analysis clearly shows they are not suspect shipments and they are well separated in time from any implicated outgoing shipments. They will also create a flow diagram to illustrate the traceback. Most traceback investigations resemble a branching tree because of multiple suppliers throughout the distribution chain.

Summary

Produce tracebacks pose challenges for the industry and investigators because of the perishability of the product. This means that most traceback investigations rely heavily on records kept by companies throughout the distribution chain, especially inventory records. Investigators begin a traceback at the point of sale or service of the implicated food item and work backwards through the distribution chain until they reach the point of production.

Data collected from companies that handled the suspect product throughout that chain form the basis for the analysis and flow diagrams of the investigation. Having that data available speeds the investigation and brings it to conclusion as quickly as possible.

The absence of records means that everything is suspect and everyone might be implicated. Keeping records of produce shipments helps a company establish the route its products took to get to market – an "alibi" during a traceback search. The sooner the company's records can show its products should not be implicated, the narrower the search becomes.

Quick resolution to traceback investigations offers several benefits: protection of public health, minimal disruptions to business operations, and the least amount of publicity or public concern.

Source: U.S. Food and Drug Administration's advice to its public health investigators on conducting a traceback: Guide to Traceback of Fresh Fruits and Vegetables Implicated in Epidemiological Investigations