NERL Research Abstract
EPA's National Exposure Research Laboratory
GPRA Goal 8 - Sound Science
APMs # 664 and # 682
Significant Research Findings
Improved Dietary Exposure Potential Model for
Estimating Exposure and Identifying Sources
Purpose Dietary models can be used for identifying the importance of diet relative to
other exposure pathways and to indicate 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), has been developed by NERL for this purpose. Though not intended
for risk analysis, the model has proven valuable for designing exposure
measurement programs, prioritizing highly consumed and highly contaminated
foods for use as guidance in human exposure field studies and data
interpretation, and identifying data gaps when establishing priorities for dietary
exposure research. Exposure estimates may also be conducted based on
consumption characteristics of children.
Research The NERL DEPM, a personal computer-based application program, correlates
Approach food consumption and contaminant residue data from the national-scale food
monitoring programs in a format that allows dietary exposure estimates. The
resident database system includes several government-sponsored food intake
surveys and chemical residue monitoring programs, including the U.S.
Department of Agriculture's (USDA's) Continuing Survey of Food Intakes by
Individual (CSFII) and Pesticide Data Program (PDP), and the Food and Drug
Administration's (FDA's) Total Diet Study and regulatory 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 800 exposure core food types with the same
major ingredients, established from over 6500 common food items. The
summary databases are aggregated in a fashion to allow analyst selection of
demographic factors, such as age and gender groups, geographical regions,
ethnic groups, and economic status. Daily intake is estimated by the model for
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over 300 pesticides and environmental contaminants. In addition, contributions
to total exposure from exposure core food groups and individual exposure core
foods can also be estimated.
Several improvements to enhance DEPM's applicability for dietary exposure
evaluation have been recently incorporated. The DEPM recipe files were
modified to include tapwater as a food ingredient so that food groups and items
with highest contamination from included tapwater could be determined. Other
improvements allow the user to combine residue data from multiple residue
databases for specified chemicals for more complete coverage across all foods
eaten, and to incorporate foods or chemicals, and their residues and
consumption data, that are not included in the DEPM databases. The DEPM
databases have been upgraded with several new chemicals, and USDA's
Pesticide Data Program residue data and NHANES in consumption data have
been added.
Major
Findings and
Significance
The DEPM has been used by both NERL and non-EPA exposure scientists for
numerous dietary exposure evaluations and analyses. Examples include
identification by the DEPM of food items potentially implicated in total
ingestion of disinfection by-products (e.g., trihalomethanes, haloacetonitriles,
and haloacetic acids) from tapwater. The model was also used to predict food
groups and items with highest total amounts of certain pesticides so that
duplicate diets collected in an exposure field study could be aggregated for
analysis in a fashion that would maximize detection limits.
Historical information on what people eat and what residues have been found in
foods is used by the DEPM to estimate potential dietary exposure. The resident
databases contain perhaps the most extensive collection of food residue
information assembled in a single location and made available to the exposure
scientist. Therefore, the DEPM provides the exposure research community
with a valuable tool for the utilization of existing food-related information in
evaluating the potential for dietary exposures.
Research The following manuscripts describing the DEPM have been published.
Collaboration
an(' . . Berry, M.R., Tomerlin, J.R. A Dietary Exposure Potential Model Using Extant Databases to
Publications Estimate Exposure to Chemical Residues. In: Proceedings of the EPA/AWMA
International Speciality Conference: Measurement of Toxic and Related Air
Pollutants; Air and Waste Management Association, Pittsburgh, PA; VIP-64; pp.
819-28, 1996.
Tomerlin, J.R., Berry, M.R., Tran, N.L., Chew, S., Petersen, B.J. Tucker, K.D., Fleming, K.F.
Development of a dietary exposure potential model for evaluation of dietary exposure
to chemical residues in food. Journal of Exposure Analysis and Environmental
Epidemiology 7: 81-102, 1997.
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Dietary Exposure Potential Model (Version 3.3.2 - May, 2000). Available online:
http ://www. epa.gov/nerlcwww/depm. htm.
DEPM enhancements and periodic updates of the resident databases are
planned. An updated DEPM is anticipated within the year, with more recent
residue data and a function to import food diaries created by the user from
available software for automated coding of food diaries into the national
consumption survey food coding structure.
Evaluation and testing by human exposure scientists is needed to determine (1)
how successful the process of creating the current DEPM has been and (2) how
the model can be further improved and enhanced to meet their needs.
Exposure researchers using DEPM 3.3.2 are encouraged to provide feedback,
along with inquiries about the dietary model, to:
Maurice Berry, Ph.D.
U.S. Environmental Protection Agency
National Exposure Research Laboratory
26 W. Martin Luther King Dr.
Cincinnati, OH 45268-1320
Phone: (513)569-7284
E-mail: berry.maurice@epa.gov
The recent improvements to DEPM have been supported under EPA contract
68-W7-0031 withNovigen Sciences, Inc.
Future
Research
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