# Presentation: 868525

## 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**
**Modifications to the Draft Risk Assessment**
**Data and Modeling **
**Results**
**‘****What-if’ Scenarios**
**Conclusions and Interpretations**

## Background and Process

## Technical and Scientific Reviews of the FDA/FSIS Risk Assessment

**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**

## 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

## 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**

## Risk Assessment Modeling

**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**

**Risk Assessment Modeling**

## 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**

## +

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## +

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**1**

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**1**

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**5**

**6**

**1**

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## The Listeria “Problem”

**Continue to improve public health by determining  which foods and human populations should  receive  the most**
**attention**

## 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)**

## 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)**

## 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)**

## 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**

## 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. **

## Exposure Assessment

## 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**

## Food Categories

**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**

## 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)**

## 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**_

## Frequency of Consumption

**Smoked seafood****	****	****  200****	****	****  57**
**Soft unripened cheese        4,410****	****	****  29**
**Pasteurized milk****	****       87,000****	****	****244**
**High fat dairy products     21,000****	****            13**
**Fermented meats****	****         1,800****	****	****  46**
**Deli meats****	****	****       21,000****	****	****  56**
**Deli-type salads****	****       13,000****	****	****  96**
**Pate****	****	****	****            120****	****	****  57**
**Total RTE foods****	****     340 billion servings/year**

**    ****Servings/Year-US****	****Amount/serving**
**          ****(millions)****	****	****       (g)**

## Recent Contamination Data at Retail

**	****	****	****Total    < 0.04      0.1    1     10    100   10 ****3****   10 ****4****   10 ****5****   10 ****6**
**All Deli Salads****	****	****11,236  10,793   244   47    19       4       2       1      **
**	**
**Smoked Seafood ****	****	****   2687     2573     67   11     19      8       6        1       0        2**
**Deli Meats****	****	****   9199     9117     42    20    10      2       7        1**
**Soft Ripened Cheeses ****	****   1347     1333     12     0       2 **
**Bagged Precut Leafy Salad****	****   2963****	****2941     17     1      1      2      1**
**Fresh Soft Cheese****	****	****   2936     2931       2      0      0     3**
**Soft mold-ripened Cheeses     2970     2933      30     3      3     1**
**Pasteurized Milk****	****	****   5412     5411        1**

**Gombas *****et al*****., 2003**
**IDFA, 2000**

- cfu/g at retail

## Home Refrigerator Temperatures (°F)

**Home Refrigerator Temperatures (°F)**

- Audits International, 1999

## Generic Storage Times

**Generic Storage Times**

## New Data for Deli Meats and Frankfurters

**AMI survey**
**Home storage of deli meats and frankfurters**

| Storage Time
(days) | Percentage of Pre-packaged deli meats & frankfurters |
| --- | --- |
| 1 - 3 | 39 |
| 4 - 7 | 45 |
| 8 - 10 | 7 |
| 11 - 14 | 5 |
| 15 - 21 | 1 |
| 22 - 30 | 1 |
| 31 - 60 | 1 |

## Summary of Exposure to L. monocytogenes

**Summary of Exposure to *****L. monocytogenes***