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Microbiological and Chemical Exposure Assessment

Dietary Exposure Potential Model

A Model Using Extant Food Databases to Estimate Dietary Exposure to Chemical Residues
Latest Version 5.0 Released April, 2003


Dietary models can be used for identifying the importance of diet relative to other exposure pathways and indicating the potential for high exposure of certain populations. Existing consumption and contaminant residue databases, normally developed for purposes such as nutrition and regulatory monitoring, contain information to characterize dietary intake of environmental chemicals. A model and database system, termed the Dietary Exposure Potential Model (DEPM), correlates extant food information in a format for estimating dietary exposure. The resident database system includes several national, government-sponsored food intake surveys and chemical residue data from monitoring programs. A special feature of the DEPM is the use of recipes developed specifically for exposure analysis that link consumption survey data for prepared foods to the chemical residue information, which is normally reported for raw food ingredients. Consumption in the model is based on 11 food groups containing approximately 820 exposure core food (ECF) items with similar basic ingredients, established from mean values of cosumption of over 6700 food items commonly identified in food surveys. The summary ECF databases are aggregated in a fashion to allow analyst selection of demographic factors, such as age/gender groups, geographical regions, ethnic groups and economic status. Daily intake is estimated by the model based on mean values of residues reported for over 350 pesticides and environmental contaminants. In addition, contributions to estimated dietary exposure from ECF groups and individual ECFs can also be estimated. The model was developed for personal computers with the data files designed in dBASEIV® with FoxPro for Windows® application programs for queries and reporting. Though not intended for risk analysis, the model has proved to be a suitable tool for designing and interpreting exposure measurements, identifying data gaps and establishing priorities for dietary exposure research.

The current version of the DEPM culminates a multi-year process which began by inventorying available food consumption and food residue databases for integration into a format conducive for dietary exposure modeling. Several enhancements to the previous versions (V2.3; 1996 and V3.3.2; 2000 and V4.0; 2002) have been made based on recommendations from exposure scientists. The major enhancement include:

  • Periodically updated and expanded consumption and contaminant residue databases;
  • Improved internal documentation;
  • An integrated COMBINE tool, which allows the user to combine residue data from multiple residue databases for specified chemicals and foods;
  • A USER-DEFINED DATA tool, which allows the user to incorporate foods or chemicals, and their residues and consumption data, that are not included in the resident databases;
  • A TAP WATER option, which allows the user to estimate the contribution of tap water to daily dietary exposure;
  • A tool which allows users to IMPORT FOOD DIARIES for exposure analysis. Diary files for importing are created by the user from the Food Intake Analysis System (FIAS) software for automatic coding of foods into the USDA/NHANES coding structure. Contact University of Texas, Human Nutrition Center (hnc@utsph.sph.uth.tmc.edu) for coding software

DEPM V5.0 has additions to and updates to 2000 of USDA's Pesticide Data Program and FDA's Total Diet Study contaminant residue databases. DEPM (Version 5.0 - April, 2003) may be downloaded by individuals involved in dietary exposure evaluation. DEPM V5.0 has not been extensively tested and feedback from users is encouraged. DEPM is available as a self-installing executable file, DEPM50.EXE. Please note that this file is 23 megabytes in size. Installed, DEPM requires approximately 95 megabytes of hard disk space.

For additional information , contact Dr. Lisa Melnyk (melnyk.lisa@epa.gov) by e-mail or by postal mail at USEPA, National Exposure Research Laboratory, 26 W. Martin Luther King Drive (MS-564), Cincinnati, OH 45268. The DEPM was developed for USEPA by Exponent, Inc. (formerly Novigen Sciences, Inc.) and Environ Corp., Washington, DC.

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