Microbial Risk Assessment Guideline
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EPA/100/J-12/001 USDA/FSIS/2012-001 MICROBIAL RISK ASSESSMENT GUIDELINE PATHOGENIC MICROORGANISMS WITH FOCUS ON FOOD AND WATER Prepared by the Interagency Microbiological Risk Assessment Guideline Workgroup July 2012 Microbial Risk Assessment Guideline Page ii DISCLAIMER This guideline document represents the current thinking of the workgroup on the topics addressed. It is not a regulation and does not confer any rights for or on any person and does not operate to bind USDA, EPA, any other federal agency, or the public. Further, this guideline is not intended to replace existing guidelines that are in use by agencies. The decision to apply methods and approaches in this guideline, either totally or in part, is left to the discretion of the individual department or agency. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. Environmental Protection Agency (EPA) (2012). Microbial Risk Assessment Guideline: Pathogenic Microorganisms with Focus on Food and Water. EPA/100/J-12/001 Microbial Risk Assessment Guideline Page iii TABLE OF CONTENTS Disclaimer .......................................................................................................................... ii Interagency Workgroup Members ................................................................................ vii Preface ............................................................................................................................. viii Abbreviations ................................................................................................................... ix Executive Summary…………………………………………………………………….xii 1. Introduction .................................................................................................................. 1 1.1 Who is this Guideline Written For? ................................................................. 1 1.2 What are the Benefits of this Guideline? ......................................................... 2 1.3 What are Some Fundamental Differences between Microbes and Chemicals? .......................................................................................................... 3 1.4 What are the Components of a MRA that I Should Consider? ..................... 6 1.5 How is this MRA Guidance Related to Other MRA Frameworks/Guidelines that are Currently Available? ................................. 8 1.6 What MRA Principles MRA Should I be Aware Of? .................................... 9 1.7 How can the MRA be Used? ........................................................................... 11 1.8 What Are Examples of Types of MRA? ........................................................ 12 1.9 What Types of Decisions within Risk Assessment are Science Policy?....... 13 1.10 Why are Uncertainty and Variability in MRA Important? ......................... 15 1.11 Summary ........................................................................................................... 16 2. Planning and Scoping ................................................................................................ 17 2.1 What is Planning and Scoping? ...................................................................... 17 2.1.1 What is Problem Formulation? ............................................................ 18 2.2 What do I Consider When Deciding to Initiate a MRA? ............................. 19 2.3 What “Depth” Can I go into in the Risk Assessment? ................................. 21 2.4 What Elements are Discussed During Planning and Scoping? ................... 23 2.4.1 What are Risk Management Questions and What is the Charge? ... 27 2.4.2 What is a Risk Profile? ......................................................................... 27 2.4.3 What is a Conceptual Model? .............................................................. 28 2.4.4 How are Data Gaps Identified and Addressed in the Context of Planning and Scoping? .......................................................................... 29 2.4.5 What is an Analysis Plan? .................................................................... 32 2.4.6 How do I Consider Information Quality Including Data Quality? .. 32 2.4.7 What is Value-of-Information Analysis? ............................................ 35 2.4.8 What is a Communications Plan? ........................................................ 35 2.5 Who Can be Involved with Planning and Scoping? ..................................... 36 2.6 Summary ........................................................................................................... 37 3. Hazard Identification and Hazard Characterization ............................................. 38 Microbial Risk Assessment Guideline Page iv 3.1 What are Hazard Identification and Hazard Characterization? ................ 38 3.2 How do I Define the Hazard? ......................................................................... 39 3.3 What Hazard Characteristics Can I Consider? ............................................ 40 3.4 How do Microbial Hazards Cause Adverse Outcomes? .............................. 41 3.4.1 What does Virulence and/or Pathogenicity Mean in the Context of Causing an Adverse Outcome? ............................................................ 42 3.5 What are the Mechanisms that May Lead to the Development of New Pathogens or Pathogens with New Traits? .................................................... 43 3.6 What are the Major Categories of Microorganisms? ................................... 44 3.7 What Methodological Approaches are Used to Identify and Quantify Microorganisms?.............................................................................................. 46 3.8 Are there Concerns Regarding Microbial Detection Methods? .................. 47 3.9 What Host Factors Can I Take into Consideration? .................................... 51 3.10 How does Life Stage Affect Sensitivity to Infection and Disease Manifestation? .................................................................................................. 53 3.11 What Environmental Factors Can I Take into Consideration? .................. 54 3.12 Summary ........................................................................................................... 55 4. Dose-Response Assessment ....................................................................................... 56 4.1 What is Dose-Response Modeling and What are Some General Considerations for Dose-Response Modeling? .............................................. 56 4.1.1 How do I Choose Between Modeling a Discrete Dose Versus an Average Dose? ........................................................................................ 57 4.1.2 What is the Difference Between a Threshold and a Non-Threshold Model? .................................................................................................... 58 4.1.3 What is the One-Hit Model and When is it the Preferred Model? ... 58 4.1.4 What Important Factors Can I Consider in Dose-Response Assessment? ........................................................................................... 60 4.1.5 How Can I Model the Spread of Disease in the Population?............. 67 4.1.6 What Can I Address for Each Model to Improve Transparency? ... 69 4.2 What is Current Practice in Quantitative Dose-Response Modeling for Microbial Illness? ............................................................................................. 70 4.2.1 What Models Can I Use for Microbial Dose-Response Assessment? 70 4.2.2 What is the Output of a Dose-Response Assessment?........................ 76 4.2.3 How do I Fit Models to Existing Dose-Response Data? ..................... 77 4.2.4 How Can I Evaluate Uncertainty in Dose-Response? ........................ 79 4.2.5 What is Variability in Dose-Response? ............................................... 80 4.2.6 How Can I Account for Life Stages and Different Populations in Dose-Response Models? ........................................................................ 81 4.2.7 Can I Use Uncertainty, Modifying, or Adjustment Factors in a Microbial Dose-Response Assessment? ............................................... 81 4.2.8 Are Other Modeling Methods Being Developed? ............................... 82 4.3 Summary ........................................................................................................... 83 5. Exposure Assessment ................................................................................................. 84 5.1 What are General Concepts in Exposure Assessment? ................................ 84 Microbial Risk Assessment Guideline Page v 5.1.1 What is an Exposure Assessment? ....................................................... 84 5.1.2 What are Sources, Pathways, and Routes of Exposure? ................... 85 5.1.3 How are Fate and Transport Considered in Exposure Assessment? 88 5.1.4 What Environmental Factors Can I Take into Consideration?........ 89 5.1.5 What is an Exposure Scenario? ........................................................... 90 5.1.6 What are Qualitative and Quantitative Exposure Assessments? ..... 90 5.1.7 What is Variability in Exposure Assessment? .................................... 91 5.1.8 What is Uncertainty in Exposure Assessment? .................................. 91 5.1.9 What is a Deterministic Exposure Assessment? ................................. 92 5.1.10 What is a Stochastic Exposure Assessment? ....................................... 92