Presentation on theme: "Module 4 – Environmental Health Investigation"— Presentation transcript:
1 Module 4 – Environmental Health Investigation Foodborne Disease OutbreakInvestigation Team Training:Module 4 – Environmental Health InvestigationEstimated time: 90 minutes
2 Module Learning Objectives At the end of this module, you will be able toDiscuss how contributing factors are related to the causative agent, suspect food, and food processing method.Compare an environmental health assessment with a HAACP plan review, facility plan review, and regulatory inspection.List types of activities included in an environmental health assessment.Describe the likely role of local jurisdictions in a traceback investigation.At the end of this module you will be able toDiscuss how contributing factors are related to the causative agent, suspect food, and the food processing method.Compare an environmental health assessment with a HAACP plan review, facility plan review, and a regulatory inspection.List types of activities included in an environmental health assessment.Describe the likely role of local jurisdictions in a traceback investigation.Environmental health investigators present today are likely to be very familiar with the content of this module. The intent is more to help other investigators on the outbreak investigation team understand the roles and responsibilities of the environmental health investigator as well as the information provided through the environmental health investigation that can be useful to them.> Learning objectives
3 Food System Primary producers Retailers Distributors Manufacturers The food system in the United States is diverse, interconnected, and complex.The involved business entities extend from farm to fork and include: Primary producers (farms, ranches, orchards, fisheries, seed producers) Distributors (importers, cooperatives, wholesalers, packers, repackers, shippers) Manufacturers Retail outlets (grocery stores, supermarkets, convenience stores, warehouse clubs) and point of service establishments (restaurants, fast food establishments, delicatessens, food courts, food carts)Food/food products can become contaminated and unsafe anywhere along this continuum. Furthermore, unsafe food introduced in the chain of production and distribution can be spread to many other points, thereby quickly amplifying the magnitude of the problem.DistributorsManufacturersPoint of service establishments
4 Food Establishments as Dynamic Systems ServeHoldAssembleReheatPackageUnderlying FactorsFoods and their propertiesFood workersEquipmentProcessesPoliciesManagementEconomicsOUTPUT: Final productCoolStoreINPUTS:- Raw foods- Ingredients- Chemicals- Packingmaterials- WaterMost food establishments are complex systems influenced by many interrelated and changing factors.Most food establishments have a number of inputs to the system in terms of raw materials, ingredients, chemicals, packing materials, and water and one or more outputs (i.e., final products).A variety of processing steps are undertaken to transform the inputs to the outputs including preparation, cooking, storage, and assembly (any of which could be done correctly or incorrectly).A number of underlying factors affect the safety of the final product including the quality of the ingredients (and their innate properties), food workers and their ability to perform their assigned tasks in a satisfactory manner, equipment design and maintenance, the preparation/cooking processes themselves, establishment policies, other management decisions, and the economics driving those decisions.The inputs, processing steps, and underlying factors are always changing in a complex and interactive manner. Ingredients are obtained from different sources, new equipment is purchased, employees perform different tasks on different days/at different times, new employees are hired, and processing steps and policies are modified. Changes to any one aspect of the operation impact other components of the operation.Since many interrelated components affect the final product produced by a food establishment, environmental health investigators need to understand the underlying interactions of all of the forces that impact the system and address the deeper factors to improve the outcome. They need to use a systems approach.CookReceivePrepStore
5 Contributing FactorsNote to instructor: This is just a transition slide to indicate topics. Move to next slide before beginning lecture.
6 Contributing FactorsFactors that increase the risk of foodborne illnesses and repeatedly contribute to outbreaksIdentification (and correction) of these factors facilitates prevention and control of foodborne diseasesThree major categoriesContaminationSurvivalProliferationContributing factors are environmental factors that increase the risk of the occurrence of a foodborne illness and repeatedly contribute to certain kinds of foodborne disease outbreaks.The identification of contributing factors (and their correction) helps in the prevention and control of foodborne diseases. However, identifying the specific contributing factors leading to a foodborne outbreak can be one of the most challenging aspects of foodborne outbreak investigations.Contributing factors include factors that introduce or otherwise permit contamination of a food, factors that allow survival of or failure to inactivate the contaminant, and factors that allow for proliferation of the causative agent (and elaboration of toxin).Note to instructors: Mnemonic device for categories of contributing factors: Risk factors that Cause Sick People> Contributing factors
7 Categories of Contributing Factors Categories of Contributing FactorsContaminationSurvivalProliferationNatural toxinAdded poisonous substanceToxic containerContaminated food eaten raw or lightly cookedUnsafe sourcesCross-contaminationInfected food workerUnclean equipmentPoor storage practicesImproper cooking or heat processingImproper reheatingInadequate acidificationInsufficient thawingfollowed byinsufficient cookingImproper refrigerationPreparation too far in advance of servingProlonged cold storageImproper hot-holdingInsufficient acidificationInsufficiently low water activityInadequate thawing of frozen foodsAnaerobic packagingInadequate fermentationNote to instructor: Do not read through this list but rather help students appreciate the large number of contributing factors that can be at play and that they can be divided into three major categories. Because each list of contributing factors is revealed one at a time, you might ask students to name examples of each type of contributing factor before advancing the slide to reveal the list.Contributing factors can be classified into three major categories: Contamination, survival (or failure to inactivate), and proliferation. I will describe these categories further and give an examples of each.[Advance slide.] Contamination factors introduce or permit contamination by pathogenic microorganisms, natural toxins, or other poisonous substances. There are many ways foods can become contaminated. An example is bare-hand contact of a ready-to-eat food by an infected food worker who did not wash their hands and use gloves properly.[Advance slide.] Survival factors allow survival of pathogenic microorganisms or fail to inactivate heat-labile toxins. A number of different factors result in the survival of pathogenic microorganisms. An example is improper cooking/heating (intended to kill microorganisms and inactivate heat labile toxins) of a food during preparation or processing.[Advance slide.] Proliferation factors allow pathogenic bacteria to multiply to numbers sufficient to cause illness or toxigenic bacteria and molds to elaborate toxins. Again, many different factors can allow proliferation of microorganisms already present on food. An example is improper hot-holding of food on a serving line where temperatures are too low to prevent bacterial growth and might even promote bacterial growth over time.> Contributing factors
8 Contributing FactorsPresence alone may not be sufficient to cause illnessA relationship exists between contributing factors, food vehicle, causative agent, and processing methodsPresence of a contributing factor alone is not sufficient to cause foodborne illness. If subsequent steps in the production and/or use of the food control the problem introduced by the factor, the factor will no longer contribute to a potential problem. For example, eggs are commonly contaminated with Salmonella. But if the eggs are cooked properly, the Salmonella will be killed and no longer pose a threat to the consumer.In addition, not all contributing factors have relevance with all causative agents, foods, or food processing methods. For example, botulism is usually associated with food processing and storage practices, not ill food workers (since it is not spread from ill food workers). Scombroid food intoxication is often linked to the source of the fish and refrigeration practices, not inadequate cooking temperatures (since the toxin is not destroyed by normal cooking temperatures).Natural reservoirs and growth requirements of a causative agent, the food itself, and usual methods of producing and processing the food will impact which contributing factors are most likely to come into play for any particular situation. As a result, patterns of contributing factors have emerged between specific causative agents, food vehicles, and processing methods.> Contributing factors
9 Common Contributing Factors by Causative Agent and Food Situational Keys A-F (starting on page 80)The International Association for Food Protection’s Procedures to Investigate Foodborne Illness has summarized the most common contributing factors for specific foods, causative agents, and settings in the Situational Keys A-F. The information in these keys is based on prior outbreak investigations, epidemiologic studies, challenge tests, and food safety research.Let’s look briefly at this resource. Open your copy of Procedures to Investigate Foodborne Illnesses to page 80. Leaf through the next couple of pages. You will see that the keys are organized by food type starting with meat and poultry on pages 80-81, followed by eggs and dairy on pages 82-83, followed by fish and seafood and so on and so forth. The pages are further subdivided by specific types of food.Within each type of food, the rows represent the most common causative agents for that food type and the columns represent specific contributing factors in certain setting (settings being farm/field, processing, and retail store/food service/home). Symbols are used to indicate which factors are most likely to come into play for a certain food, causative agent, and setting.You will note that there are a lot of symbols used in these tables, but you should zero in on the x’s (PRINCIPLE FACTORS TO CONSIDER) and checks (FACTORS TO CONSIDER) as those are the most likely contributing factors in play in these food-causative agent-processing method combinations.For example … [Instructor should select an example that they can comfortably walk through.]> Contributing factors
10 Generalizations Causative agent Common contributing factors Spore formers andpreformed toxinsCooling, reheating, hot holding, bare- hand contact, room temperature storage, cold holdingViral infectionsIll food worker, bare-hand contact, inadequate handwashing, contaminated raw products, contaminated surfacesBacterial infectionsIll food worker, bare-hand contact, inadequate handwashing, contaminated raw product, cross-contamination, inadequate cookingParasitic infectionsContaminated raw products, source, water, cross-contamination, inadequate cookingNote to instructor: Do not read this table or go over it in detail. If appropriate, provide a quick example using the table.This table highlights common contributing factors across the different general types of causative agents. Realize that these are gross generalizations and contributing factors differ by specific causative agent, food, and food processing method.Nonetheless, these generalizations can be helpful early in an investigation, before the causative agent is confirmed. If the epidemiologic and laboratory investigators suspect a certain kind of agent (based on signs and symptoms, incubation period, duration of illness, or suspect food), sharing that information as soon as possible can help the environmental health investigator focus their search for contributing factors.> Contributing factors
11 Class Question Are the following likely to be contributing factors for the outbreaks described?Contributing factorBare-hand contact of lettuce in an out- break of shigellosis linked to a salad barRefrigerator at 47 in an outbreak of hepatitis A virus linked to a restaurantRefrigerator at 47 in an outbreak of Staphylococcal intoxication linked to potato saladSo, just to make sure everyone understands the relationship between contributing factors, causative agents, food, and the processing method, let’s look at a few situations and say whether they are likely to represent contributing factors for a particular type of outbreak. (These are pretty simple, so you will not have to use Procedures to Investigate Foodborne Illness to answer them.)None of these situations represent good food preparation practices. But depending on the food, causative agent, and food processing method, some could have contributed to the specific outbreak whereas others are just poor food preparation practices.Cat in the kitchen of a restaurant prior to an outbreak of norovirus> Contributing factors
12 Environmental Antecedents The root cause or circumstances that set the stage for contributing factors to occurInclude economic constraints, inadequate worker education, management decisions, social and cultural beliefsMust be addressed to eliminate contributing factorsSo contributing factors are environmental factors that increase the risk of a food safety problem. But every food safety issue ultimately becomes a human resource issue.“Antecedents” are the circumstances behind the contributing factors that allowed the contributing factors to occur. They include things like inadequate worker education, behavioral risk factors, management decisions, and social and cultural beliefs. Only by identifying the problem behind the problem will investigators be able to develop effective interventions that will prevent future occurrences of the problem.> Contributing factors
13 Example Salmonellosis outbreak linked to potato salad Contributing factor: Potato salad contaminated because placed under thawing chicken in refrigeratorEnvironmental antecedents: Economic issues led to hiring more part-time workers who were less experienced, inadequate food worker education, inadequate oversight and supervisionFor instance, an environmental health assessment was undertaken for an outbreak of salmonellosis that was linked to potato salad served at a restaurant. Investigators determined that the potato salad was probably contaminated with Salmonella from chicken that was thawing above the ingredients in the refrigerator. The root of the problem, however, was deeper than that.To save money, the manager had begun hiring more part-time workers whom he could pay less. Although the workers had taken a food safety course from the local health department, they were inexperienced and did not always make good decisions on foodhandling practices. And, unfortunately, the workers were not closely supervised.Corrective actions included education of the food workers but more importantly the addition of a kitchen manager who supervised all food workers, oriented new employees, and provided oversight.> Contributing factors
14 “When you have a foodborne outbreak, more than one thing went wrong.” A prolific writer and researcher, Dr. Frank Bryan, once said “When you have a foodborne outbreak, more than one thing went wrong”.Dr. Frank Bryan> Contributing factors
15 Environmental Health Assessment Note to instructor: This is just a transition slide to indicate topics. Move to next slide before beginning lecture.
16 Environmental Health Assessment A systematic, detailed, science-based evaluationFocuses on factors that contributed to an outbreakDifferent from aHazard Analysis and Critical Control Point (HACCP) risk assessment reviewFacility plan reviewFood establishment regulatory inspectionAn environmental health assessment is a systematic, detailed, science-based evaluation of environmental factors that contributed to transmission of a particular disease in an outbreak. An environmental health assessment focuses on the problem at hand and considers how the causative agent, food vehicle, processing methods, contributory factors, and environmental antecedents interacted to result in the problem.An environmental health assessment differs from an Hazard Analysis and Critical Control Point (HACCP) risk assessment review, a facility plan review, and a general inspection of operating procedures or sanitary conditions used in a regulatory inspection of a restaurant or food- production facility. Let’s look more closely at each of these activities to better understand how they differ.Note to instructor: The terminology used to refer to these various activities may vary by jurisdiction. The outbreak investigation team, however, needs to understand the terminology used by all players to ensure effective communication.> Env’t health assessment
17 HACCP Risk Assessment Review Preemptive solutions to potential food safety problems in the futureUndertaken before a problem occursFocusFoods produced by establishment and related proceduresIdentification of potential food safety problemsControl measures to mitigate potential problemsInitiated by establishmentA Hazard Analysis and Critical Control Point (or HACCP) risk assessment review addresses food safety problems that might occur in the future. The review is undertaken before a food safety problem occurs, often (but not always) when a new food establishment is opened, a new owner takes over, or a new food is added to the menu. The review is preventive and proactive.The goal of a HACCP review is to identify potential food safety hazards in the production of the final food product (i.e., circumstances that may lead to contamination, survival, or proliferation of pathogens) as well as control measures for each identified hazard. HACCP reviews are used at all stages of food production and preparation processes including packaging, distribution, storage, and service. HACCP is an industry tool and responsibility and is initiated by the food establishment.HACCP risk assessment reviews are useful only if the plan is put into action, not just stored on a bookshelf.> Env’t health assessment17
18 Facility Plan ReviewPreemptive solutions to potential food safety problems in the futureUndertaken before a problem occursFocusProposed structural plans and equipment at establishmentRelation to intended proceduresFunctionality, durability, ease of cleaningInitiated by establishmentA facility plan review also addresses food safety problems that might occur in the future. Like a HACCP review, the facility plan review is undertaken before a food safety problem occurs. It is preventive and proactive.A facility plan review provides a systematic evaluation of structural plans, equipment, and related procedures prior to construction and opening of a facility. (“Build it better. Clean it easier. Save Lives.”) For example, a proposed kitchen with no sinks for handwashing is at high risk for future food safety problems.A good facility plan review is a valuable food safety tool and should not just be red tape.> Env’t health assessment18
19 Food Establishment Regulatory Inspection Addresses food safety problems occurring todayRoutinely scheduled inspectionsFocusOngoing processes and proceduresLeading causes of foodborne illness (risk-based approach)Initiated by regulatory authorityRegulatory inspections address food safety problems occurring at the establishment on the day of the inspection - today. They are routinely scheduled and are undertaken when there is no specific information (e.g., outbreak or complaint) to suggest any process in the establishment is out of control. They focus on the present situation and what could potentially cause illness or a foodborne outbreak at the facility.In the past, regulatory inspections revolved around legal compliance checklists. Currently, regulatory inspections are more of a risk-based approach that focuses on the leading causes of foodborne outbreaks and conditions most likely to cause foodborne illness. Priorities will vary by type of food being produced but often include:Employee healthPersonal hygiene program (e.g., handwashing, bare-hand contact)Time temperature managementCleaning and sanitization of food contact surfaces (e.g., work tables, cutting boards, processing equipment)Cross contamination related to storage and preparationDate markingActive managerial control of risk factorsThe regulatory inspection is initiated by the authority that licenses and regulates that specific kind of establishment.> Env’t health assessment
20 Environmental Health Assessment Addresses food safety issues that occurred in the pastOccurs in response to a food safety problemFocuses on (and reconstructs) past events related toImplicated food(s)Prepared/served during outbreak periodOutbreak investigation team initiates, guided by epidemiologic and laboratory informationEnvironmental health assessments address food safety problems that occurred in the past. They are conducted when information suggests food safety problems are not adequately controlled at a food establishment (e.g., complaints are received about the establishment or a foodborne disease outbreak has been linked to the establishment).The environmental health assessment focuses on the vehicle implicated in an outbreak, if known, during the period in which the outbreak exposure occurred. If the vehicle is not known, the assessment focuses on the setting in which the problem occurred or is suspected to have occurred and the most likely sources of food safety problems.The environmental health assessment reconstructs past events and tries to determine what might have occurred to cause that particular foodborne outbreak. The decision to undertake an environmental health assessment is made by the outbreak investigation team based on consumer complaints, laboratory results, or epidemiologic associations. The environmental health investigator takes the lead in performing the assessment.It is important to remember, at any given time, there is likely to be multiple violations of the Food Code or other potential food safety problems at most food establishments. In a regulatory inspection, investigators might have to look at all of those violations, but in an environmental health assessment, investigators focus only on problems that contributed to the outbreak under investigations.> Env’t health assessment
21 Summary HACCP/Facility Plan Review Regulatory Inspection Env’t Health AssessmentWhen undertakenBefore a food safety problem occursRegularly scheduledTime focusFutureTodayFocus of effortAreas where food safety problems could occurOngoing processes focusing on common problemsWho initiatesFood establishmentRegulatory agencyIn response to specific problemPastFood safety problems related to implicated food during outbreak periodOutbreak inves-tigation team> Env’t health assessment
22 Environmental Health Assessment Objectives:Reconstruct past events, focusing on implicated food(s)Identify contributing factorsIdentify environmental antecedentsDevelop effective interventionsThe environmental health assessment is key to a foodborne outbreak investigation. So let’s talk more about the environmental health assessment to gain a better understanding of the activities involved and sources of information.The objectives of the environmental health assessment at a food establishment implicated in an outbreak are toReconstruct pass events, focusing on implicated foodIdentify contributing factorsIdentify environmental antecedentsDevelop effective interventions based on contributing factors and environmental antecedentsThe environmental health assessment may actually indicate that the food safety problem lies elsewhere, thereby vindicating the implicated food establishment. This, too, is important because it allows investigators to redirect their resources in a productive manner to the most likely source of the outbreak.> Env’t health assessment
23 Preparation for Assessment Examine available outbreak informationCausative agentOnset of illness among casesLikely exposure dates/meals/foodsCollect food establishment informationExisting regulatory recordsMenus, recipes, product formulationsConnection to chain of food establishmentsReview information on causative agentReservoirs and previously identified vehiclesModes of transmissionLikely contributing factorsFor an environmental health assessment to move smoothly and be most successful, the environmental health investigator needs to prepare for the assessment. Preparation includes:Review of available outbreak information such as the causative agent (if known), timing of onset of illness among cases, likely exposure dates/meals/foodsReview of what is known about the implicated food establishment through existing regulatory records (e.g., regulatory inspections, customer complaints); available menus, recipes, and product formulations; and whether the establishment is part of a food chain (sharing sources of raw materials, food processing methods, or establishment policies with other food establishments)Review of information on the causative agent such as reservoirs and previously identified vehicles, modes of transmission, and likely contributing factorsThis information will allow the environmental health investigator to focus his or her efforts on the most likely sources of contamination and contributing factors.Where will the investigator get this information? From the team epidemiologist, the regulatory food inspector, the laboratorian, and reference books such as those that have been given to you for this course.> Env’t health assessment
24 Site Visit Focus on implicated food and time period of outbreak Manager interviewFacility walk throughObservation of operationsCollection of samples (food and environment)Worker interviewsCollection of records (and other documents)Note to instructor: Before advancing slide, ask participants to list some of the activities that they would do at a site visit related to the environmental health assessment of a food establishment implicated in an outbreak.[Advance slide.]After preparation, the environmental health investigator will visit the implicated food establishment. We call this the site visit. During the site visit the investigator will undertake many different activities focusing on the implicated food and time period including:Manager interviewFacility walk throughObservation of operationsCollection of samples (food and environment)Worker interviewsCollection of records (and other documents)The site visit might benefit from the presence of the regulatory food inspector as he/she will be more familiar with the establishment (and its management), the food preparation processes, and other operating procedures. However, the size of the investigation team also might be an issue, so the lead environmental health investigator will need to decide the value of including additional staff on the site visit.If an environmental health assessment requires multiple visits to the implicated facility, efforts should be made to include the same investigators for continuity.An environmental health assessment typically takes 2-3 times the amount of time required for a routine regulatory inspection of the same facility. For example if the regulatory inspection of a facility takes on average 1 hour, the environmental health assessment of the same facility during an outbreak investigation is likely to take 3 hours. The investigation of food establishments that undertake more complex food processes or are linked to a larger outbreak (i.e., more than 2 ill persons) will take longer than the investigation of other facilities.> Env’t health assessment
25 1. Manager Interview Work to gain cooperation in investigation Assess management knowledge and attitude toward food safetyCollect information about food workers who prepared the implicated foodReview standard operating proceduresThe activities undertaken during the environmental health assessment may not always occur in the same order, but the initial step is likely to be an interview with the manager from the implicated establishment. The goal will be to gain management cooperation during the investigation and to get a general sense of the operations and conditions that might have contributed to the outbreak.Developing a positive, communicative relationship with the manager will engender an atmosphere of cooperation. Obtaining the manager’s full cooperation will result in quicker responses to requests and the collection of more complete and accurate information (and ultimately a more successful investigation). To aid in communications with management, the investigator will explain the reason for the investigation, the investigation objectives, and likely activities. He or she will emphasize that the purpose of the investigation is to determine events or activities that may have contributed to the outbreak so that preventive measures can be taken to prevent similar problems in the future.At this point, the investigator can begin to assess management knowledge and attitude toward food safety which might provide insights to possible food safety problems (and solutions) identified during the investigation.During the manager interview, the investigator will collect information about food workers who prepared the implicated food as well as information on the worker’s health at the time of the outbreak, personal hygiene practices, and education. Throughout the environmental health assessment, there should be no disclosure of confidential information about workers to others (including the manager) in accordance Health Insurance Portability and Accountability Act of 1996The investigator will also review standard operating policies and procedures with the manager such as the HACCP plan, buyer specifications/approved sources, personal hygiene and sick worker policies, worker education, processes for cleaning and sanitizing equipment or environmental surfaces, time/temperature procedures, recipes, and instructions and collect written copies, where available.> Env’t health assessment
26 2. Facility Walk ThroughGet sense of general layout of facility and floor designWalk through movement of implicated food through facilityIdentify opportunities for occurrence of relevant contributing factorsA general sense of the layout of the facility will make the assessment easier. The investigator will consider the floor design of the facility and employee traffic patterns.The investigator will accompany workers on a quick walk through the facility to see where the implicated food is moved or stored from receiving and storage of raw materials or ingredients to shipment or serving of the finished product.Tracking the flow of foods through the facility can be especially useful in evaluating potential sources of cross contamination. The investigator will consider such things as whether there is adequate separation between food preparation activities to prevent cross-contamination or if hand sinks are situated close enough to prep tables to facilitate hand washing by workers.> Env’t health assessment
27 Example Food Flow through Facility The food flow through the establishment can be diagrammed. These diagrams show where the food and its ingredients have been and can help investigators identify possible points where cross contamination could have occurred. They can also illustrate the accessibility of hand sinks and provide insights to handwashing practices at the establishment.> Env’t health assessment
28 3. Observation of Operations Focus on implicated food and associated processesAttempt to reconstruct how food was prepared during period of interestTake measurementsRecord observations on food preparation worksheetDraw flow diagramThe investigator will then observe procedures used to make the implicated food during the period of interest (sometimes called a food processing/preparation review). This will include all steps from receipt of raw ingredients to the finished product. The investigator will examine how the ingredients were cleaned and stored. He or she will observe how foods were thawed, cooked, cooled, reheated, served, and transported. The investigator will determine what equipment was used in the preparation of the suspect food and the condition of that equipment. The investigator will measure time and temperature conditions to which the food and/or its ingredients were exposed during storage and preparation. The investigator will try to determine the weight/volume of food prepared and the depth of containers used to store the food. He or she may also measure water activity, sugar content, and pH of the suspect food to determine if the causative agent could survive/proliferate in the food.As the investigator observes food preparation, he or she will consider likely contributing factors associated with the particular food and causative agent and necessary control points to prevent food safety problems.If no food has been implicated at the time of the environmental health assessment, the investigator will likely focus on high-risk foods based on the causative agent (known or suspected) and type of food establishment.> Env’t health assessment
29 Example Food Preparation Worksheet FOOD PREPARATION REVIEW WORKSHEETComplaint Number:Establishment Name: _________________________________________________Address: Phone Number:___________________Date & Time of Suspect Meal: / : am pmmo day yrDate & Time Food Preparation: / : am pmPerson Interviewed: Name PositionReview: Observing Preparation Interviewing person who made food__Other (specify)Suspect Food: ________________________________________________Food preparation worksheets will help in the systematic collection of information about the operations observed.Each row in the worksheet represents one operation undertaken on the suspect food and the details about that operation including time of day the process was undertaken, the amount of food prepared, the temperature of the food, the equipment used, the depth of containers, whether there was hand contact with the food, and the worker’s name and health.Investigators will use this information to draw a flow diagram for the implicated food item.DATEPROCESSOBSERVATIONAMOUNT OFFOODTIME OF DAYTEMP OF FOODEQUIP- MENT USEDDEPTH OF CONTAINEROR FOOD THICKNESSHAND CONTACT WITH FOODWORKER’S NAMEWORKER’S HEALTHOTHER INFOYNIllWell> Env’t health assessment
30 Example Flow Diagram > Env’t health assessment Wooden cutting board cleaned with soapy clothCelery stored under thawing chickenCelery and red pepper from grocery store50 lbs. bag of potatoes from Farmer BWashed and choppedEggs in trays of 32 from Farmer B, stored in walk-in refrigeratorEggs boiled for 10 min.Eggs slicedPotatoes, celery, red pepper, and eggs mixed gently with wood spoon5 lbs. potatoes washed and peeledPotatoes boiled in water until tenderPotatoes cooled and cubedCubed potatoes marinated in French dressingKnife used to cut other items cleaned with soapy water at end of daySame wooden spoon used to get mayonnaise and all mixing4 cups of mayon-naise added and stirred into mixture with wooden spoonStored in walk-in refrigerator at 4C (39 F) for up to 2 daysPotato salad placed in resealable container (cylindrical 8 in. x 14 in.)Paprika sprinkled on topFlow diagrams can help display the flow of operations. They can be used to verify production activities as different workers/managers are consulted. They can also help identify possible points of contamination or microbial survival and proliferation.In these flow diagrams, each operation is represented by a rectangle. (NOTE: an “operation” is very narrowly defined. Each operation is more like one very detailed step in the recipe.) Arrows indicate the direction of flow of the process. The investigator notes other important information directly on the diagram including measurements (e.g., temperature, duration of operation) and the name of the person(s) performing the operation.The flow diagram should include storage, preparation, cooking, cooling, reheating, and service. As additional information is collected in the investigation, it should be noted on the flow diagram.Chopped parsley stirred into mixturePotatoes cooled and parsley washed and chopped finelyBrand Z Paprika from grocery storeServed directly from container onto customer’s plate with ice cream scoopFresh parsley from grocery store> Env’t health assessment
31 4. Collection of SamplesCollect food, water, and environmental samples based on suspicions about outbreak sourceConsult with laboratory on collection, storage, and transportation proceduresCollect as soon as possible and note condition (may store for testing at later time)Suspicions about the likely source of the outbreak and results from epidemiologic studies or the environmental health assessment itself will guide sample collection. Likely, the investigator will collect leftover samples of the implicated food and ingredients, and where appropriate, swab food preparation surfaces or equipment for culture or other testing.The investigator will collect ingredients or raw items used in the suspect food if they are likely sources of contamination. If no foods are available from the suspect meal or lot, the investigator might collect sample of items that have been prepared subsequently but in a similar manner.Investigators should work with the laboratory on collection and storage of samples so that:A sufficient amount is submitted to perform all necessary laboratory tests and so that the sample is representative of the food item.Investigators do not contaminate the samples themselves.The samples are in the best condition possible when received by the laboratory.> Env’t health assessment
32 5. Worker Interviews Interview in private Reconstruct preparation of implicated food during period of interestNote unusual circumstances during period of interest and inconsistencies in the storyCollect information about food worker hygiene and recent illnessesInvestigators will interview the food workers involved in the preparation of the implicated food (and possibly their supervisors).Investigators should interview workers in private (i.e., not in the presence of co-workers or management) because workers will be more open and honest when interviewed alone. The goal will be to reconstruct what happened with regards to the implicated food during the period of interest.The investigator should ask the worker to reconstruct processes/operations associated with the implicated food focusing on the timeline. Although the investigator should allow the worker to tell their story, asking questions in a chronological sequence can help guide the worker.The investigator should ask about any unusual circumstances that may have happened during the outbreak period such as malfunctioning equipment, short staffing, worker illness, or recent changes in processes. Investigators should make note (and possibly follow-up) on any inconsistencies identified.The investigator also will collect information about the food workers themselves, including use of gloves, handwashing practices, and recent illnesses.> Env’t health assessment
33 6. Collection of Records Collect and review Records that identify source of food or ingredients (e.g., receipts and invoices)Worker logs or time cardsMonitoring logs (e.g., temperatures in walk-in refrigerators)The investigator will review available records and collect identifying information about the implicated food or its ingredients including the brand name; producer; distributor; batch and lot number; dates produced, shipped, and received; and quantities received. This information is collected to determine the exact source of the food item (and to facilitate traceback of the item, if appropriate). Receipts, invoices, and shipping documents will be most helpful in this process.In addition, investigators will review worker logs or time cards and monitoring logs (e.g. temperatures in walk-in refrigerators), where appropriate.> Env’t health assessment
34 Group Exercise Divide into groups by table. Study the information provided on an outbreak of salmonellosis linked to a restaurant at the end of the module.Walk through the environmental health assessment of the restaurant, answering the questions.Do you see any contributing factors likely to be related to the outbreak?FULL-SIZED HANDOUT: Undertaking an Environmental Health Assessment (at end of module)Be prepared to share your thoughts with the class.Time: 15 minutes
35 Group Exercise (cont’d) Group Exercise (cont’d)An outbreak of gastrointestinal illness is linked to a local restaurant. Seven unrelated restaurant patrons are sick with abdominal pain, nausea, vomiting, and diarrhea. Onset of illness among cases was January Two ill patrons had stool specimens positive for Salmonella.Question 1: You are responsible for undertaking the environmental health assessment. How would you prepare for the investigation?An outbreak of salmonellosis is linked to a local restaurant. Seven restaurant patrons are sick with abdominal pain, nausea, vomiting, and diarrhea. You are responsible for undertaking the environmental health assessment.How would you prepare yourself?Possible answers:Examine available information on the outbreak: When the patrons became ill, when they ate at the restaurant, whether a food has been implicated.Collect existing information on the facility: results of regulatory inspections or complaints, menusReview basic information on salmonellosis: Reservoirs, common vehicles, and likely contributory factors
36 Group Exercise (cont’d) Group Exercise (cont’d)The restaurant is known for its burgers but serves a variety of sandwiches and salads. Based on patient interviews, ill persons ate at the restaurant on January 20. All but one ate chicken salad; three ill persons had only chicken salad.Question 2: What type of activities will you under-take at the facility?Based on patient interviews by the public health nurse, all patients ate at the restaurant on January 20. All but one ate chicken salad.What type of activities will you undertake?Environmental health assessment activities will zero in on the preparation of the chicken salad, contributing factors, and environmental antecedents with a focus on the time period of the outbreak. There are a whole host of activities you will undertake. Here are just a few:You will talk with the manager to find out who prepared the chicken salad on the day of the outbreak, general operating procedures, oversight provided by management and supervisors. You will observe the food worker preparing the salad, taking measurements where appropriate. You will interview the food worker to try to reconstruct preparation of the salad on the day the outbreak occurred and any unusual circumstances. You will try to determine the worker’s personal hygiene (including handwashing), whether they were recently ill, their knowledge of food safety, and level of oversight by management/supervisor. You will likely collect left over samples of the chicken salad, if available, or raw ingredients, if appropriate. You might decide to swab environmental surfaces if contaminated equipment might have contributed to the outbreak.
37 Group Exercise (cont’d) Group Exercise (cont’d)Question 3: Given the causative agent (Salmonella), implicated food (chicken salad), and setting (food service establishment), what contributory factors will you be looking for?Given the causative agent (Salmonella), implicated food (chicken salad), and setting (food service establishment), what contributory factors will you be looking for?Contributory factors associated with bacterial outbreaks from earlier slide (Slide 9): Ill food worker, bare-hand contact, inadequate handwashing, contaminated raw product, cross-contamination, inadequate cookingFrom Key F in Procedures to Investigate Foodborne Illness under mixed salad (containing protein with ingredients that need to be heated) and Salmonella (page 96-97), contributory factors include: cross contamination, contaminated environment, improper cleaning of equipment, inadequate refrigeration, room temperature holding, heat process failure, and improper cooling.The manager tells you two employees (Willard and Anita) usually make the salad. Making the chicken salad is a 2-day process. You interview the employees to reconstruct how the salad was made.
38 Group Exercise (cont’d) Group Exercise (cont’d)Question 4: Draw a flow diagram for preparing the chicken.Note to instructor: Do not belabor the flow diagram. It is just to give all participants an appreciation of how these are created and how additional information can be included on the flow diagram.
39 Group Exercise (cont’d) Question 5: These photos were taken as you ob-served the salad being made. Do any concern you?123To the experienced eye, many questions will be raised by these photos. Here are just a few of the concerns raised by a seasoned environmental health specialist:Washing raw chicken in prep sink – Handwashing procedures after bare-hand contact with raw chicken; potential for contamination to splash on nearby surfaces; sanitation of sink afterwardDicing of cooked chicken on cutting board – Quantity of food in container could result in slow cooling; sanitation of cutting board (when was it last washed); glove policy, if anyCooked chicken in deep container, covered with plastic wrap - Depth of container; storage with compatible products in the refrigeratorWalk in refrigerator with raw meat placed over celery – Potential for contamination of ready-to-eat food.Slicing of celery to be used in salad – Bare-hand contact of celery, a ready to eat food; sanitation of cutting surface and knifeAssembly of the salad components – Location of food prep area in relation to where the raw chicken was handled; mental and physical health of food worker; sanitation of utensils456
40 Develop Effective Interventions Immediate control measuresHoldSeizeCease/desistLicense sanctionsMenu limitationEmbargoClosureWorker exclusion or restrictionsRecallsLong term strategies to prevent recurrenceHACCP planRisk control plansTrainingMenu/supplier/recipe modificationsBefore we leave the environmental health assessment portion of this module, we will touch upon the remaining objective of the environmental health assessment: the identification of effective interventions.This slide lists a few of the specific control measures used in foodborne disease outbreaks. Implementation depends on the specifics of the outbreak and the authority of the investigating jurisdiction.Although the environmental health investigator might implement some control measure on an urgent basis to quickly address continuing food safety problems, it is likely that the entire team will work together in determining the overall plan to control the outbreak.The standards of evidence that need to be met in order to implement control actions vary significantly from place to place and depend on the authorities granted to investigators and their agencies by local, state, or federal public health or food regulatory laws. It is critical that investigators know what interventions their agency is authorized to implement and is able to share that information with the team, as needed, during an outbreak investigation.> Env’t health assessment
41 Traceback Investigation Note to instructor: This is just a transition slide to indicate topics. Move to next slide before beginning lecture.
42 Traceback Investigations Process used to determine the production and distribution chain of an implicated foodPurpose:Identify product so that it can be removed from further consumptionDetermine likely origin of food safety problemStrengthen epidemiologic associations between food and illnessFormal regulatory traceback vs. informational tracebackA traceback investigation is the process used to determine the production and distribution chain of a suspicious food item during an outbreak investigation. A traceback investigation collects identifying information for the implicated food product and determines where the food eaten by cases has been.The purposes of traceback investigations include:Identify source and distribution of foods implicated in an outbreak to support efforts to remove contaminated food from further consumption.Determine the origin of the food safety problem by examining locations in common among foods eaten by cases.Compare distribution of illnesses and implicated food to strengthen epidemiologic associations. (Convergence of foods eaten by cases supports the conclusion that the food is the likely source of the outbreak.)Formal regulatory tracebacks, usually undertaken by USDA or FDA, follow the rules of “chain-of-custody” and are used to provide evidence in a court of law (e.g., to mandate a product recall). Written records (e.g., receipts, invoices, bills of laiding) are necessary to substantiate a recall.Sometimes state and local health department staff initiate what is referred to as “informational tracebacks” or "rapid source tracing". These sorts of tracebacks are undertaken early in an outbreak investigation and can quickly identify obvious commonalities between cases, help in the interpretation of epidemiologic data, and assess the potential success of a formal regulatory traceback. They do not meet the standards of a formal regulatory traceback, however, and cannot be used to mandate a food product recall.> Traceback investigation
43 Results of Traceback Investigations Results of Traceback InvestigationsCASESPOINT OF SERVICEESTABLISHMENTSDISBUTORS/IMPORTERSPRODUCERS/PROCESSORSGroceryStore AImporter XDomesticProducer BProducer CForeignProducer ADomesticProducer ACase #1Distributor ARestaurant ADomesticProducer BCase #2-4,6, 8Cafeteria XDistributor BDistributor DDistributor DDomesticProducer CCase #5, 7,13-17Restaurant BImporter XA traceback investigation begins with information from cases about their purchase of the implicated food item and extends back to the beginning of its production. Information is collected from: cases, point of service establishments, distributors/importers, and producers/processors. Throughout this process, collection of receipts and invoices is critical. Without them, a traceback would not be possible.Ultimately, the traceback allows the distribution chain for the implicated foods eaten by patients to be determined. Sometimes diagrams such as this one are developed.Identification of a common place(s) among foods eaten by different cases is a strong indicator that contamination of the food occurred at or before that point in the production and distribution of the food. Environmental health assessments of these places can then help identify the specific points of contamination and conditions that may have led to contamination.In this particular example (which is really not very complex), can you see the one location common to foods consumed by all cases? [Advance slide.] Indeed, it is Distributor D.Now this does not mean that Distributor D is the source of the problem. It could be, but what it does mean is that contamination likely occurred at or before that point. So contamination might have occurred at Distributor D or at Importer X, Domestic producer A, Domestic producer B, Domestic producer C, or Foreign producer A.Case #7,9-12Deli AForeignProducer ADistributor C> Traceback investigation
44 Role of Local Health Departments Undertake scientifically sound investigations toImplicate specific food itemRule out end user contaminationInterview cases for product details and where they purchased the food (e.g., receipts)Collect paperwork (e.g., receipts, invoices, shipping documents) from retail food establishmentsFormal regulatory traceback investigations require a detailed review of cryptic, hard to read invoices and shipping and receiving documents and analysis of mountains of information including dates of production, shipping, receiving; quantities; and sources and conditions of foods received. They require knowledge of the involved industry and food distribution patterns and chain of custody (and lots of time!!!). As a result, USDA and FDA staff usually coordinate these investigations and even take the lead in carrying them out.Nonetheless, local and state staff play an important role in traceback investigations.Traceback investigations rely on good, solid data about the outbreak. A poorly executed local investigation might implicate the wrong vehicle and misdirect subsequent investigations. So completion of a thorough and scientifically sound outbreak investigation by local and state staff is paramount.Local and state staff also must determine that the source of the contamination is within the production chain of the food and is not the result of mishandling of food by an end user (single food service establishment or private home). Traceback investigations are time-consuming and resource intensive. If contamination results from mishandling by the consumer, retailer, or a food service establishment, a traceback investigation would not be necessary and should not be performed.In addition, local and state staff usually perform specific tasks that support the traceback investigation itself:They are often the first to interview cases about exposures that might have led to the illness including details about foods eaten during the outbreak period. Therefore, they have an opportunity to collect detailed product information early in an investigation when recall is best.They have regulatory authority over all or portions of the retail food industry (e.g., restaurants, grocery stores) in their jurisdiction and have developed relationships with those establishments. That relationship puts them in a good position to interact with food establishments in their jurisdiction and collect paperwork useful to the traceback. Collection of appropriate paperwork (e.g., receipts, invoices, and shipping documents) is critical.> Traceback investigation
45 Traceforward Investigations Once source of outbreak identified:Process used to trace distribution of all implicated lots of food from the original source (not just foods eaten by known cases)PurposeSupport recall effortsSupport further case-findingTest hypothesis about sourceTraceback investigations may lead to the identification of an ongoing public health threat and a consequent need to take appropriate actions, such as recall of foods or warnings to consumers. To accomplish these tasks, investigators will do a "traceforward" investigation to determine the distribution of all implicated lots of food from the source of contamination to other establishments including retail stores, warehouses, distributors, restaurants, and other firms in commerce.This information can also help epidemiologists identify additional cases of disease associated with the outbreak and can be used to test hypotheses about the outbreak.Like tracebacks, traceforwards are resource intensive and should only be undertaken when there is a reasonable degree of confidence that the traceback correctly identified the source of the implicated product and there is a need to recall the product.> Traceback investigation
46 Example > Traceback investigation Domestic Producer A Grocery Store ACase #1Distributor ARestaurant ADomesticProducer BCase #2Distributor BDistributor CCase #3-6Cafeteria XDomesticProducer CDomesticProducer CCase#8-17Restaurant BImporter XForeignProducer A> Traceback investigation
47 Example > Traceforward investigation Cases Grocery Store B Grocery Store ADomesticProducer EDomesticProducer DCase #1Distributor ARestaurant ACase #2Distributor BDistributor CCase #3-6Cafeteria XDomesticProducer CCase#8-17Restaurant BDistributor ECasesGroceryStore CDomesticProducer FProcessor ACasesDeli A> Traceforward investigation
48 Salmonella Typhimurium and Peanut Butter Cluster of S. Typhimurium detected by PulseNetStudies implicate peanut butter sold to institutions and peanut butter crackersOutbreak traced to one plantInitial recall of specific lots of peanut butter expanded to include all peanuts and peanut products from implicated plantFDA performs traceforwardUltimately 3,900 products recalled from several hundred companiesThe importance of the traceforward investigation is clearly highlighted in the multistate outbreak of Salmonella Typhimurium that was linked to peanut butter in The peanut butter and paste from the implicated processing plant was used as an ingredient in numerous peanut butter containing products, including cookies, crackers, ice cream, frozen meals, and dog treats leading to a recall of almost 4,000 products.On November 10, 2008, CDC's PulseNet staff noted a small and highly dispersed multistate cluster of Salmonella Typhimurium isolates with an unusual PFGE pattern from 12 states. CDC, working with state and local partners, began an epidemiologic assessment of the cluster that was growing in number.In open-ended interviews with patients, 77% of cases reported they were likely to have eaten peanut butter in the 7 days before becoming ill. By comparison, 59% of the general public reported eating peanut butter in the previous 7-day period in the FoodNet food consumption survey.Minnesota investigators identified an institutional association which led to the identification of a particular brand of peanut butter. The outbreak strain was isolated from open and unopened jars of the implicated peanut butter which was only marketed to institutions. However, many patients had not eaten peanut butter in institutions, but had eaten other peanut butter-containing products. Subsequent case-control studies indicated significant associations between illness and consumption of any peanut butter and specific brands of prepackaged peanut butter crackers.Further investigation suggested that peanut butter and peanut paste produced at one plant were the source of the outbreak. In January 2009, the implicated plant voluntarily stopped production of peanut butter and peanut paste and specific lots of peanut butter were recalled. In the subsequent weeks, the recall was expanded to include all peanuts and peanut products processed at the implicated plant since January 1, 2007 including: peanut granules, peanut meal, dry roasted peanuts, oil roasted peanuts, peanut butter, and peanut pasteBecause these products were ingredients in many foods produced and distributed by other companies, FDA inspectors undertook a traceforward investigation and traced shipments of the implicated products to other businesses to identify additional products that might be affected. Ultimately, more than 3,900 products from several hundred businesses were voluntarily recalled.> Traceforward investigation
49 Quick QuizThese “quick quizzes” are meant to be a rapid self-assessment so that participants can see if they understood the most important concepts in this module.The instructor will read the question aloud.Think about the answer for a moment.When asked, please indicate your answer by raising the appropriate color-coded card.If you do not get an answer right, please make note of it and revisit the module during the break or over lunch (or talk to the instructor) to see if you can determine the correct answer. This is meant to be quick. We will not discuss the answers at any length.[NOTE: Instructors should make sure everyone is aware of the correct answer and briefly explain why it is the answer, but should not go into great detail. The detailed explanations with each question are provided to you to make sure you agree with the answer. If students have questions they should ask the instructor during the break or over lunch.]
50 Quick QuizWhich of the following statements is true about contributing factors.An outbreak will occur if a contributing factor is present.The three major categories of contributing factors are contamination, survival (lack of inactivation), and proliferation.Contributing factors in an outbreak depend on the causative agent but not the food vehicle or processing method.Correction of the contributing factor will correct the food safety problem and prevent it from occurring again.ANSWER: B. The three major categories of contributing factors are contamination, survival (lack of inactivation), and proliferation.Contributing factors can be classified into three major categories: Contamination, survival (or failure to inactivate), and proliferation.Presence of a contributing factor alone is not sufficient to cause foodborne illness. If subsequent steps in the production and/or use of the vehicle control the problem introduced by the factor, the factor will no longer contribute to a potential problem.Not all contributing factors have relevance with all causative agents, foods, or processing methods. Natural reservoirs and growth requirements of a causative agent, usual methods of producing and processing the food, and the setting in which the food is prepared will impact which contributing factors are most likely to come into play for any particular situation.The identification of contributing factors (and their correction) helps in the prevention and control of foodborne diseases, but correction of the contributing factor alone will not prevent the food safety problem from occurring again. Identification (and correction) of the environmental antecedents, underlying factors that led to the occurrence of the contributing factors, is necessary.
51 Quick QuizAn environmental health assessment of a food establishment undertaken during an outbreak investigation is similar to a regulatory inspection except it focuses on the past.TrueFalseANSWER: B. False.An environmental health assessment differs from a regulatory inspection of a restaurant or food-production facility.Regulatory inspections address food safety problems occurring at the establishment on the day of the inspection. They are routine scheduled inspections undertaken when there is no specific information (e.g., outbreak or complaint) to suggest any process in the establishment is out of control. They focus on the present situation and what could potentially cause illness or a foodborne outbreak at the facility.Environmental health assessments address food safety problems that occurred in the past. They are conducted when information suggests food safety problems are not adequately controlled at a food establishment (e.g., complaints are received about the establishment or a foodborne disease outbreak has been linked to the establishment). The environmental health assessment focuses on the vehicle implicated in an outbreak, if known, during the period in which the outbreak exposure occurred.
52 Quick QuizTo prepare for an environmental health assessment, the investigator might consult which of the following?Team epidemiologistLaboratory staffRegulatory inspector for facilityAll of the aboveANSWER: D. All of the aboveFor an environmental health assessment to move smoothly and be most successful, the environmental health investigator needs to prepare for the assessment. Preparation includes:Review of available outbreak information such as the causative agent (if known), timing of onset of illness among cases, and likely exposure dates/meals/foodsReview of what is known about the implicated food establishment through existing regulatory records (e.g., regulatory inspections, customer complaints) and available menus, recipes, and product formulationsReview of information on the causative agent such as reservoirs and previously identified vehicles, modes of transmission, and likely contributing factorsThis information will allow the environmental health investigator to focus their efforts on the most likely sources of contamination and contributing factor and can be obtained by consulting the team epidemiologist, the regulatory food inspector, and laboratory staff.
53 Quick QuizAll of the following activities might be performed during an environmental health assessment of the implicated facility in an outbreak EXCEPTInterview of the manager of the implicated facilityWalk through of the facilityCollection of information from ill food workersObservation of all food preparation processes undertaken at the facilityANSWER: D. Observation of all food preparation processes undertaken at the facility.The environmental health assessment will focus on the food vehicle implicated in an outbreak, if known, during the period in which the outbreak exposure occurred. If the vehicle is not known, the assessment focuses on the setting in which the problem occurred or is suspected to have occurred and the most likely sources of food safety problems.During the site visit the investigator will undertake many different activities, focusing on the implicated food, includingManager interviewFacility walk throughObservation of operationsCollection of samples (food and environment)Worker interviewsCollection of records (and other documents)The investigator will observe procedures used to make the implicated food during the period of interest, not all food preparation processes undertaken at the facility.
54 Quick QuizStaff from local health departments are likely to be responsible for all of the following activities during a traceback investigation EXCEPTInterview of cases for product detailsDetermining whether contamination at the food service facility is the source of the outbreakCollection of paperwork from the implicated food establishmentDetailed analysis of receipts and invoicesANSWER: D. Detailed analysis of receipts and invoices.Local and state staff play an important role in traceback investigations includingCompleting a thorough and scientifically sound outbreak investigation that implicates the true source of the outbreak.Ruling out end user contamination from mishandling of the food by the consumer, retailer, or a food service establishment.Collecting detailed product information during early interviews of cases (when recall is best) and receiptsCollecting paperwork from the implicated facility (e.g., receipts, invoices, and shipping) that can be used to identify the specific food vehicle (e.g., brand, lot, preparation date)Formal regulatory traceback investigations require detailed review of cryptic, hard to read invoices and shipping and receiving documents and analysis of mountains of information including dates of production, shipping, receiving; quantities; and sources and conditions of foods received. They require knowledge of the involved industry and food distribution patterns and chain of custody (and lots of time!!!). As a result, USDA and FDA staff usually take the lead in these investigations and analyze the results.
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