How Food Contamination Investigations Are Evaluated for Claims and Litigation

The Centers for Disease Control and Prevention (CDC) estimates that six major pathogens caused approximately 9.9 million domestically acquired foodborne illnesses in the United States annually, based on estimates for circa 2019. When Toxoplasma gondii is included, the seven pathogens were estimated to cause 53,300 hospitalizations and 931 deaths each year.

Behind each of those numbers sits a potential claim and a chain of evidence that investigators, regulators, and other stakeholders may evaluate when determining the source and scope of contamination.

The gap between what an investigation uncovers and what can be reliably documented may significantly affect how contamination findings are evaluated. Regulatory findings and supporting technical records may follow different documentation standards, and a single documentation lapse in that chain, such as a missing collection report or an undocumented custody transfer, may complicate interpretation of the resulting evidence.

Regulatory jurisdiction, traceback methodology, laboratory analysis, and evidence documentation practices may affect how food contamination investigations develop and evaluate evidence.

Key takeaways: How food contamination investigations may support claims evaluation

Regulatory jurisdiction and investigative methodology influence how findings are evaluated and interpreted.

What may influence the investigation

• Three federal agencies divide jurisdiction by product type rather than contamination type: the Food and Drug Administration (FDA), the Food Safety and Inspection Service (FSIS), and the CDC
• Source confirmation depends on whether epidemiological, traceback, and testing data point to the same source
• Chain of custody is often important to the integrity, traceability, and interpretation of laboratory results

How findings are evaluated

• Whole genome sequencing (WGS) is the primary subtyping method, but a match alone may not establish that a specific food caused a specific illness
• When expert opinions are used in legal proceedings, the opinions are generally expected to be supported by sufficient facts, reliable methods, and reliable application of those methods

Rimkus applies forensic investigation and toxicology methods to assist with the food contamination matters that underlie claims and litigation. Contact us to discuss a case.

What regulatory framework applies to food contamination investigations?

Jurisdiction typically depends on the product rather than the hazard, and three federal agencies operate under distinct statutory mandates that may help determine which investigation record applies. Under the Food Safety Modernization Act (FSMA), the FDA’s Hazard Analysis and Risk-Based Preventive Controls (HARPC) framework defines a food safety hazard as any biological, chemical (including radiological), or physical agent with the potential to cause illness or injury. The contamination category may affect both the investigation approach and the liability theory that follows.

Misidentifying which agency holds jurisdiction over an implicated product may have downstream effects on both regulatory analysis and litigation strategy. In mixed-product cases, investigators often resolve this determination first.

FDA jurisdiction and FSMA authority

FDA oversees the safety of approximately 80% of all food consumed in the United States, covering all food except meat, poultry, and egg products. FSMA, signed into law in 2011, shifted FDA’s approach from reactive response toward preventive controls. FSMA’s mandatory recall authority, facility registration suspension power, and “prohibited act” designation for preventive control non-compliance may each carry direct litigation relevance.

A mandatory recall may reflect a federal determination related to adulteration. A prohibited-act finding may support a negligence per se argument in subsequent litigation.

USDA/FSIS and HACCP requirements

FSIS derives its authority from the Federal Meat Inspection Act, the Poultry Products Inspection Act, and the Egg Products Inspection Act. Meat and poultry establishments under FSIS jurisdiction must maintain Hazard Analysis and Critical Control Point (HACCP) plans per 9 CFR Part 417.

CDC surveillance role

CDC holds no regulatory enforcement authority over food producers. Its role is epidemiological: surveillance, outbreak detection, and coordination with FDA and FSIS. PulseNet, the national laboratory network for detecting bacterial enteric disease outbreaks, has used WGS as its primary subtyping method since 2019. The Foodborne Diseases Active Surveillance Network (FoodNet) tracks laboratory-confirmed infections from a defined group of enteric pathogens across ten sites covering approximately 15 to 16 percent of the United States population (roughly 54 million people).

How does traceback and source identification work?

Traceback typically reconstructs the distribution and production chain, documenting the source of a product implicated in a foodborne illness investigation. FDA’s Coordinated Outbreak Response and Evaluation (CORE) Network, established in 2011, investigates and responds to outbreaks potentially linked to FDA-regulated food products.

Investigators trace food that ill people report eating back through the supply chain to a farm or production facility. Products may pass through multiple intermediaries between farm and consumer. Each transfer point is both a potential contamination source and a potential gap in the evidentiary record, particularly where distributors lack electronic lot-tracking systems.

Early investigation scope often turns on whether contamination is transient or established. Transient contamination, where pathogens arrive through raw materials or personnel without colonizing the facility, typically focuses the investigation on a single lot or ingredient. Established environmental contamination broadens the inquiry to sanitation practices, facility design, maintenance history, and months of operational records.

Evidence convergence

CDC specifies that health officials often use three types of data to confirm the source of a multistate foodborne outbreak: epidemiological data identifying the suspected source, traceback data tracing the supply chain, and food and environmental testing data confirming whether the food is the source. Regulatory action commonly involves convergence of all three streams. In practice, an investigation producing strong evidence in only two streams may face both regulatory and Daubert standard admissibility challenges.

How does laboratory analysis support contamination investigations?

WGS replaced pulsed-field gel electrophoresis (PFGE) as the primary molecular subtyping method in 2019. FDA describes WGS as serving the same general subtyping role as PFGE, but with much higher resolution and the ability to distinguish strains that PFGE cannot.

A WGS match between a food isolate and a clinical isolate may support source identification, but it does not, by itself, establish that the food caused the patient’s illness. Regulators still need epidemiological and traceback investigations before taking regulatory action. WGS generally remains one evidentiary stream rather than standalone proof of causation.

Chain-of-custody documentation can be a vulnerable point in food contamination investigations. Chain of custody may affect whether any laboratory result, regardless of analytical sophistication, reaches the courtroom. Courts may give evidence less weight, or exclude it, when the proponent cannot adequately establish chain of custody and authenticity, or when unresolved tampering concerns remain. 

FDA’s Investigations Operations Manual requires collection reports to document sample collection methods, preparation techniques, and a description of custody. The Manual considers an analytical unit unacceptable if the method of collection does not result in a representative sample.

How may food contamination investigations support product liability cases?

Federal Rule of Evidence 702 governs the admissibility of expert testimony. The amendment effective December 1, 2023 clarified that the court must find, by a preponderance of the evidence, that the proposed testimony meets each of the rule’s reliability requirements. The rule assigns that determination to the court before testimony reaches a jury.

The Daubert framework evaluates expert reliability through testability of the methodology, peer review and publication history, known or potential error rate, standards and controls, and general acceptance in the scientific community. Courts may evaluate WGS methodology through FDA’s published regulatory applications, CDC Morbidity and Mortality Weekly Report surveillance summaries, AOAC International’s broader analytical-method validation frameworks, and its adoption as PulseNet’s new standard.

Expert witness qualifications in food safety litigation

Food safety expert witnesses typically bring backgrounds in forensic toxicology, microbiology, food science, or epidemiology. In practice, expert reports that use methodology consistent with regulatory practice, rather than opinions assembled after retention for litigation, may face fewer admissibility challenges under Rule 702. Opinions that follow the same evidence convergence framework that regulators use also may carry more weight than single-stream opinions.

From investigation findings to admissible evidence

Food contamination investigations may generate regulatory records, laboratory data, traceback documentation, and epidemiological findings that can support the evidentiary foundation for both claims assessment and litigation. The methods behind those investigations, from FDA’s environmental sampling protocols to CDC’s molecular surveillance through PulseNet, may influence whether the resulting evidence withstands scrutiny under Daubert and Rule 702.

For organizations seeking forensic investigation support, Rimkus Forensic Services and Expert Services professionals apply forensic investigation methodologies, toxicology evaluation, and expert witness services to assist with food safety, contamination, and product liability matters. Contact us to discuss case-specific needs.

Frequently asked questions about food contamination investigation procedure

What are the key differences between voluntary and mandatory recalls?

Voluntary recalls occur when a company removes a product on its own initiative, often after discovering contamination, labeling defects, or safety concerns. Mandatory recalls occur when an agency orders removal, an authority FDA gained under FSMA in 2011 and may exercise when a company refuses or delays a voluntary recall and a food is reasonably likely to cause serious adverse health consequences or death.

How do public health officials differentiate between a cluster and an outbreak?

Public health officials distinguish between a cluster and an outbreak primarily by comparing observed cases against expected baseline rates for a given population, location, and timeframe. A cluster represents an aggregation of similar health events that may or may not be statistically unusual, while an outbreak is an unexpected increase in cases that exceeds normal baseline expectations and typically signals a common exposure or ongoing transmission chain requiring immediate intervention.

How do investigators determine the incubation period of a foodborne illness?

Investigators determine the incubation period by systematically linking exposure time to symptom onset time for each confirmed case, then analyzing the distribution across multiple cases to identify the interval between consumption and illness. Investigators typically express the resulting incubation period estimate as a range with a median value rather than a single number.