Food Investigation Response Manual
Appendix 2B - Scoping and Verification during a Food Safety Investigation

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The scoping and verification component of a food safety investigation contributes to the public health outcome by identifying foods that may be or already are in distribution that contain a hazard to human health. This component also helps the CFIA meet its objective during a food safety investigation to determine if a food safety hazard exists as well as the source and extent of the problem.

In order for the CFIA to fulfill its stated objectives, when the CFIA becomes aware that a hazard exists in a product/lot, two sets of questions must be answered:

    1. Is the contaminated product in distribution?
    2. Is it at risk?
    3. What risk management actions are required?
    1. Are there other associated products (common raw ingredients, production processes and/or environment) that are in distribution?
    2. Are any contaminated?
    3. Are any at risk?
    4. What risk management actions are required?

Answers to the first set of questions come from standardized steps of risk assessment and recall decisions. Answers to the first two questions of the second set come from scoping and the verification component that is followed by risk assessment and recall decisions.

Comprehensive and properly conducted scoping of verification activities assists the CFIA to identify products in the market that are risk to consumers.

If the second set of questions are not asked and/or properly answered, potentially contaminated products that pose a risk to human health could remain in the marketplace.

It is for the reason of human health that appropriate, consistent, thorough and timely completion of scoping and verification activities during a food safety investigation is necessary.

This document summarizes the scoping and verification steps conducted during a food safety investigation procedures.

Scoping and Verification Process

The following is a stepwise description of scoping and verification activities:

Steps: (1) Compile Basic Information, (2) Develop Scoping Objective, (3) Determine Scoping Frame and (4) Food Safety Verification: (4.1) Documentary Verification and (4.2) Product Verification.

Note: These steps are mostly concurrent and build on each other.

  1. Compile Basic Information
    1. Fully identify the main product(s) that triggered the food safety investigation (FSI). (i.e. frozen raw ground beef burger without binders/spices; lot x);
    2. Fully identify the hazard. (i.e. E. coli O157:H7);
    3. List known or estimated risk level (i.e. Risk 1); and
    4. Determine from current or previous FSIs the likely cause or route of contamination (i.e. ground meat; lot y) that was made from trims, lot z, that were generated from carcasses slaughtered on date 1x).
    As the first step, item A will likely be most advanced and items B, C and D may still be developing. The final Health Risk Assessment may still be pending or in-depth characterization of microbial hazards such as Pulsed-field gel electrophoresis (PFGE) and details of various lots of raw materials may not be known. The next steps are continued while this information is developed and/or collected.
  2. Develop Main Scoping Objective

    Using the best available basic information, develop the main scoping objective. The main scoping objective should be stated incorporating all four basic components: product, hazard, risk and source of contamination. The main scoping objective is always to determine what additional products are associated with the source of contamination being considered, are these products still in distribution and what additional products are non-compliant and/or a health risk due to the presence of the identified hazard.

  3. Determine Scoping Frame

    This is a crucial activity and requires a thorough understanding of the industry practices, manufacturing processes and the likely causes. Usual contamination routes are:

    • Raw material;
    • Environment and/or equipment;
    • Process break down (insufficient cooking, cooling, sealing, etc. );
    • Packaging Materials (chemical leaching, extraneous materials); and
    • Tampering.

    The scope/extent of the concern will depend upon the likely cause, when the deficiency started and when/if it was corrected and it may also be influenced by common industry practices.

    For example:

    • An oven breakdown that was fixed at 10 am may only impact a few hours of product made during the morning period;
    • Presence of metal pieces in baked products though the flour has resulted in numerous recalls at various companies that used the flour from the same supplier;
    • Continuous contamination of meat cuts through the slicer that harbour Listeria is known to have caused the recent outbreak from products made over a few weeks;
    • Undeclared milk in dark chocolate has resulted in recalls, downstream in the distribution chain; and
    • The industry practice of identifying dairy based creamers as non-dairy creamers.

Using the determination of the likely cause develops a scoping frame, which includes all marketed products that are associated with the likely cause or the source. In cases of outbreaks, more than one associated date/lot that are a likely risk may be already known/suspected and scoping frame(s) can be developed for each and combined into a larger frame.

While the scoping frame is being developed, the status of the controls and any sampling and technical details about the products and processes are also collected and understood.

By the end of this step there will be a list of suspected products with the best available information on the quality controls, distribution and location of those products.

Food Safety Verification

The final step is food safety verification of products identified within the scoping frame.

Verification has two parts:

Documentary Verification

Documentary verification collects and analyzes all Quality Control/Quality Assurance (QC/QA) data within the scoping frame. Procedures and data are collected from various companies to develop a better understanding of the manufacturing process and various observations that are available to provide confidence in the safety of products.

Documentary verification helps to determine if the product(s) within the scoping frame were made under normal conditions and to understand the limitations, if any, and if there were any incidents / events of interest that show point(s) of possible contamination.

Product Verification

Product verification builds on documentary verification and attempts to obtain sufficient and direct observations related to suspected products within the scoping time frame.

It can:

  1. Support the conclusion that the issue was isolated;
  2. Provide evidence that the issue is more wide-spread; or
  3. Supplement a lack of documentation leading to either 1) or 2).

It is crucial that all attempts be made to conduct the product verification across the scoping frame at the same time. Comprehensive and concurrent product verification reduces the chance of repeated and multiple recalls occurring over a several week period.

Product Verification has three components: lots to sample, sample size per lot and sampling.

Lots to Sample

Number of lots to include in verification is determined using Table 1.

If documentary evidence shows time periods or events of interest as the likely source/points of contamination; then lots around those time periods / events are preferentially used for product verification. As a basic principle, safety buffers both before and after the suspected spots/events are included in the scoping frame. If however, documentary evidence reveals no pattern or spots/events as the likely source/point of contamination, a more generic spread across the shelf-life of the product is used for product verification.

Table 1: Maximum Table Note 2 number of lots to verify by Class and Hazard
HazardRisk IRisk IIRisk III
Microbial 12 6 2
Extraneous Matter 10 5 0
Chemical/Nutrition 10 5 0
Allergen 6 3 2

Table Notes

Table note 2

Table 1 will likely provide sufficient observations for the Health Risk Assessment that when combined with documentary verification can provide a basis for a larger and wider assessment, if applicable. If however, after combining documentary and product verifications only lot by lot assessments are possible, additional lots should be sampled.

Return to table note 2 referrer

Sample Size Per Lot

It is recognized that sampling a lot has its limitations even with larger numbers. However, as internationally accepted, it is also recognized that "the protection conferred on the consumer for a particular lot is seriously limited when using small number of sample units such as n=5; hence the recommendation is use large values of n when a direct hazard is recognized". (ICMSF Vol 7, 2001, pg 161). It is considered that in such situations the decision tree similar to an outline by ICMSF (ICMSF Vol 7, 2001, pg 153) will result in a more reliable assurance of safety.

Product verification involves sampling of suspected product lots within the scoping frame to obtain direct evidence. The total observations or sample results that are used in verification will include samples/tests done by the company, trade, or other government agencies and will/must include more than 50% of observations from reliable independent government agencies including the CFIA (more than 25%).

The points and/or products for verification will change for each food safety investigation. However, within the scoping frame samples that are to be taken for product verifications can be determined using the Table 1 and/or ICMSF guidelines (ICMSF Vol 7, 2001, pg 165).


Once the numbers of lots and samples have been decided, the CFIA must ensure that those samples represent the lot and scoping frame being verified.

To take a sample that properly represents a lot: the quantity, distribution and locations of units produced and available is obtained from the company. Based on the known distribution, sample units are proportionally spread across the distribution area(s) and obtained randomly. Verification samples are taken at warehouses as well as retail locations.

In summary, the product verification step attempts to obtain sufficient, representative and direct observations.

In a comprehensive analysis, the product testing results from industry sources are also included. It is therefore essential that complete sampling and testing details are obtained from companies and /or other agencies. Before external results can be included in the information for a request for a Health Risk Assessment (HRA), the CFIA must be satisfied that samples represent the lot and that testing methods and laboratories are accredited/equivalent to the Canadian standards.

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