• Home
•  »  IRAC
•  »  Events
•  »  Sep. 14, 2004
•  » Presentations

Presentations

Symposium

College Park Aviation Museum
1985 Cpl. Frank Scott Drive
College Park, MD 20740
Auditorium
September 14, 2004

Agenda

Session 1: How researchers design data collection strategies for risk assessment and decision making

Convenor : Brandolyn Thran, USA CHPPM

Abtracts

John Luchansky

Recovery Rate of Listeria monocytogenes from Commercially Prepared Frankfurters during Extended Refrigerated Storage

F. Morgan Wallace, Jeffrey E. Call, Anna C.S. Porto, George J. Cocoma, The ERRC Special Projects Team, and John B. Luchansky

To assess the prevalence of Listeria monocytogenes in vacuum-sealed packages of frankfurters, about 33,000 packages (1 lb each) were obtained by a third-party contractor from 12 volunteer commercial manufacturers over a 2-year period. The 12 producers, each of which contributed about 2,700 packages of frankfurters from one production run, comprised 9 large and 3 small plants located in eight U.S. Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) districts in 10 states. Five days after manufacture, 500 packages were sampled at the USDA/Agricultural Research Service (ARS) Eastern Regional Research Center (ERRC) in Wyndmoor, Pa., by the USDA/ARS package rinse method. At regular intervals during subsequent storage at 4 and 108C, an additional 200 packages were tested for the pathogen at each sampling point. From a statistical perspective, L. monocytogenes was not recovered from any of the products of nine of the producers, whereas the pathogen was recovered at rates of 1.5% (plant 367), 2.2% (plant 439), and 16% (plant 133) from the products of the remaining three plants. In total, 532 of 32,800 (1.6%) packages of frankfurters tested positive for the pathogen. The recovery rates did not change appreciably over time, there was no appreciable difference in L. monocytogenes recovery rates with respect to frankfurter storage temperature (4 or 108C), and the seasonality of manufacture had no in _ uence on recovery rate. Molecular subtyping of multiple L. monocytogenes–positive isolates from each plant revealed that pro. le A (serotype 1/2a) was displayed by about 90% of the 1,105 isolates tested. However, in some cases it was also possible to recover more than one pro. le from a given plant. This study provides estimates of the prevalence, types, and viability of L. monocytogenesassociated with commercially prepared frankfurters during extended refrigerated storage.

Yuhuan Chen

Abstract for NFPA presentation

The purpose of the NFPA survey on L. monocytogenes in ready-to-eat foods was to develop exposure data to support a science-based strategy for addressing Listeria monocytogenes in foods in the United States. Eight categories of ready-to-eat foods were collected over a period of 14 to 23 months from retail markets at Maryland and northern California FoodNet sites. The product categories included luncheon meats, deli salads, fresh soft ''Hispanic-style'' cheeses, bagged salads, blue-veined cheeses, soft mold-ripened cheeses, smoked seafood, and seafood salads. A total of over 31,700 samples were tested to obtain prevalence estimates with a desirable margin of error. Enumeration on all positive samples was conducted to generate data for estimating concentration distribution. Various factors considered in the study design included, among other aspects, product selection, the number of samples, and sampling site selection. Sampling was weighted by population and, for several food categories, in proportion of consumption in the FoodNet sites. This study was an outcome of team work, with funding from food industry and government agencies to address a challenging foodborne pathogen.

Richard Whiting

Listeria and Vibrio Risk Assessment Examples

How risk assessors and risk managers have utilized available data to support decision making

Richard C. Whiting
FDA, CFSAN
College Park, MD

The risk assessments currently created for microbial pathogens are unique projects. Therefore, they rarely use data specifically designed for risk assessments and must rely on a wide variety of data of different quality from many sources. If time and resources permit, conducting a preliminary quantitative risk assessment to identify critical data gaps, collecting this data, and then completing the risk assessment would be the preferable risk assessment process. However, this if often not possible and the risk assessors must make a judgment on the relevance and uncertainty of the assorted data obtained. Relevance refers to the applicability of the collected data to the specific risk assessment. Data, especially survey data, are associated with a time, location, season and other characteristics that may not exactly match the risk assessments needs. For example, five year old data are used to estimate the present values because more recent data have not been collected. Risk assessors must place uncertainty values on the data to estimate how different that data are from the data that ideally are needed. Lower quality may also contribute additional uncertainty to the data. To evaluate the impact of data quality and relevancy on the risk assessment, an uncertainty analysis is conducted and the results of the risk assessment are presented with their respective ranges of possible values due to the uncertainties. The important data quality question is therefore whether the data are good enough for the risk managers to use the risk assessment to reach a conclusion or whether the uncertainties are too great.