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Richard Whiting Food and Drug Administration December 4, 2003

Quantitative Assessment of the Relative Risk to Public Health from Foodborne Listeria monocytogenes Among Selected Categories of Ready-to-Eat Foods. Richard Whiting Food and Drug Administration December 4, 2003. Outline. Background Risk Assessment Process

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Richard Whiting Food and Drug Administration December 4, 2003

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  1. Quantitative Assessment of the Relative Risk to Public Health from Foodborne Listeria monocytogenes Among Selected Categories of Ready-to-Eat Foods Richard Whiting Food and Drug Administration December 4, 2003

  2. Outline • Background • Risk Assessment Process • Modifications to the Draft Risk Assessment • Data and Modeling • Results • ‘What-if’ Scenarios • Conclusions and Interpretations

  3. Background and Process

  4. Request for data and information Federal Register notice---1999 Public meetings Advisory Committee (NACMCF) Internal and external reviews of Data, assumptions and model Draft document Draft for public comment---Jan. 2001 Public meeting Comments, new data, improved modeling Revised document---Sept. 2003 Technical and Scientific Reviews of the FDA/FSIS Risk Assessment

  5. Contributors Team Leader: Richard Whiting, FDA Risk Assessment Modeler: Clark Carrington, FDA Project Manager: John Hicks, FDA Risk Analysis Coordinator: Sherri Dennis, FDA Scientific Advisor: Robert Buchanan, FDA Team Members (Section Leads) Mary Brandt, FDA (Consumption Section Lead), Anthony D. Hitchins, FDA, (Contamination Section Lead), Richard Raybourne, FDA (Dose-Response Section Lead), Marianne P. Ross, FDA (Epidemiology Section Lead) Team Members John Bowers, FDA; Uday Dessai, FSIS; Eric Ebel, FSIS (formerly); Sharon Edelson-Mammel, FDA; Dan Gallagher, FSIS (visiting scientist); Eric Hanson, FDA; Janell Kause, FSIS; Priscilla Levine, FSIS; Wes Long, FDA; Kathy Orloski, FSIS (formerly); Wayne Schlosser, FSIS; Carol Spease, FDA

  6. FDA/FSIS L. monocytogenes Risk Assessment • Carried out in a manner consistent with the guidelines established by Codex Alimentarius, NACMCF, and ICMSF for the conduct of a microbial risk assessment: • Transparency • Broad scientific and stakeholder input • Extensive peer review • Meets FDA and OMB Data Quality guidelines

  7. Risk Assessment Modeling • Is a tool to help risk managers reach a decision • Assembles and organizes current knowledge • Modeling is always a simplification of reality • Involves complex processes that cannot be experimentally verified • Science-based, but much interpretation and judgment on the relevance of data

  8. General Approach to Modeling • Stochastic modeling and Monte Carlo techniques • Using the entire distribution of values about an average, not focusing just on the average

  9. + 6 3 = 9 1 2 3 4 5 6 1 2 3 4 5 6 Monte Carlo Modeling: Addition of Distributions

  10. + 6 3 = 9 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 1 2 3 4 5 6 Monte Carlo Modeling: Addition of Distributions

  11. The Listeria “Problem” Continue to improve public health by determining which foods and human populations should receive the most attention

  12. Listeria monocytogenes • L. monocytogenes • Widespread • Grows at refrigeration temperatures • Listeriosis • Severe, life threatening systemic infections • ~ 500 deaths, 2000 additional cases per year in US • Immunocompromised • Mostly sporadic cases • 2-3 weeks incubation (or more)

  13. Modifications to the 2001 Draft Risk Assessment • Food Categories • Reorganized cheeses according to percentage moisture • Split frankfurters into two separate categories (reheated and not reheated) • Moved vegetable and fruit salads (w/dressings) to Deli-type Salads food category • Removed pickled, dried, and processed vegetables • Removed canned fruits and nuts • Split Miscellaneous Dairy Products into two separate categories (Cultured and High Fat Products)

  14. Modifications to the 2001 Draft Risk Assessment • New Data/ Information • Contamination data (approximately 40 studies including NFPA/JIFSAN, IDFA, FSIS) • Growth data (deli salads) • Home storage of deli meats and frankfurters (AMI Study) • Storage intervals for Smoked Seafood and Fresh Soft Cheese • Frankfurters eaten w/out reheating (AMI study)

  15. Modifications to the 2001 Draft Risk Assessment • Modeling Techniques • Weight contamination data for geographic area, age of study, size of data set (expert panel) • Correction factor for categories with no recent, large-scale contamination surveys • Separate mortality to hospitalization ratios for each subpopulation • An additional year of FoodNet data (2000) • A ‘scaling factor’ selected to adjust the uncertainty distribution for the predicted number of cases to the FoodNet estimates • Model rewritten in Visual Basic for Applications

  16. General Approach to the Lm Risk Assessment • Use contamination and growth data to predict levels at time of consumption for each food category and for all RTE foods. • Combine with epidemiology data to derive a dose-response model for each population. • Use individual food category data and dose-response model to predict number of cases per serving and total number of cases per year for each food category. • Calculate ranks and perform uncertainty analyses. Conduct “what-if” scenarios. • Compare results against knowledge of epidemiologic record and information characteristics of the foods and how they are manufactured, marketed, and consumed.

  17. Exposure Assessment

  18. Selection of Food Categories • Potential for Lm Contamination • Ready-to-eat (with one exception, foods are not cooked or reheated just prior to consumption) • History of causing listeriosis • Food contamination and consumption data • Individual foods grouped into 23 food categories

  19. Seafood Smoked Seafood Raw Seafood Preserved Fish Cooked RTE Crustaceans Produce Fruit Vegetables Meats Frankfurters, Reheated Frankfurters, Not Reheated Dry/Semi-dry Fermented Sausages Deli Meats Pate and Meat Spreads Dairy Products Fresh Soft Cheese Soft Unripened Cheese Soft Ripened Cheese Semi Soft Cheese Hard Cheese Processed Cheese Pasteurized Milk Unpasteurized Milk High Fat and Other Dairy Products Cultured Milk Products Ice Cream and Other Frozen Dairy Products Deli-type Salads Food Categories

  20. Exposure Assessment • Estimate the number of L. monocytogenes consumed • Frequency of contamination of food • Extent of contamination • Growth before consumption (EGR, temp, max growth) • Amount of food consumed at a serving (» risk per serving) • Frequency that a food is consumed (» risk per annum)

  21. Sources and Types of Data • Consumption surveys—CSFII and NHANES • Contamination data • Growth, survival and thermal inactivation data -- refrigeration, storage and cooking/reheating • Scientific, published literature, government surveys, industry data • Exposure assessment examined almost 500,000 data points

  22. Frequency of Consumption

  23. Recent Contamination Data at Retail Gombas et al., 2003 IDFA, 2000

  24. Home Refrigerator Temperatures (°F) Audits International, 1999

  25. Generic Storage Times

  26. New Data for Deli Meats and Frankfurters • AMI survey • Home storage of deli meats and frankfurters

  27. Summary of Exposure to L. monocytogenes

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