DEEM is a dietary
exposure analysis system for performing
chronic and acute exposure assessments.
DEEM was originally based on the
concepts of the EPA DRES system, but has
been greatly expanded in terms of analytical
and reporting capabilities, user interface,
and food consumption databases since it
was first introduced in the mid 1990s. DEEM
employs Monte Carlo Analysis (MCA) techniques
in order to provide probabilistic assessments
of dietary pesticide exposures when residue
data for targeted foods are available as
distributions.
DEEM can also perform
cumulative exposure analyses where the contribution
of multiple chemicals used on different
foods to the total exposure must be evaluated.
The platform was developed by Durango Software,
LLC, working closely with the scientific
staff of Novigen Sciences, Inc. of Washington
DC (now Exponent Inc.). DEEM has
been used extensively by the Office of Pesticide
Programs at EPA to evaluate human exposures
to pesticides residues in food commodities
and establish tolerances for those pesticides.
It has been used widely by agricultural
chemical companies in the U.S. and abroad,
and is also used by the environmental protection
agencies of the State of California and
Canada.
DEEM is a user-oriented,
menu-driven system that runs on IBM personal
computers and compatible microcomputers.
It operates under virtually all Windows™
operating systems.
There are two different versions
of DEEM. The first is based on the USDA
CSFII’s for 1989-91 and 1994-96, 1998
with Novigen Sciences recipe translation
factors for converting foods-as-eaten to
RACs (raw agricultural commodities) and
foodforms. The second, called DEEM-FCID™,
uses only the 1994-96, 1998 CSFII with USDA-EPA
FCID recipes to translate the foods-as-eaten
to RACs and foodforms. Both of these programs
have (nearly) identical analytical and reporting
capabilities. However, DEEM-FCID will most
likely be used by EPA in the future for
dietary assessments because the FCID database
and the DEEM-FCID program are now publicly
available. Both programs are available for
licensing from Exponent, Inc. LINK TO ORDERING
INFORMATION HERE.
DEEMand DEEM-FCID each consists
of four software modules: The main DEEM
(or DEEM-FCID) module, the Acute analysis
module, the Chronic analysis module, and
the RDFdoc utility for validating and documenting
residue distribution files (RDFs). The main
DEEM module is used to create and edit residue
files for specific chemical or cumulative
applications, and to launch the DEEM Acute,
Chronic, and RDFdoc modules. In addition,
a related program, the RDFgen residue utility,
developed at Novigen Sciences (now Exponent),
can be used to automate single analyte and
cumulative residue distribution adjustments
and the creation of summary statistics and
Residue Distribution Files (RDFs), based
on USDA Pesticide Data Program (PDP) monitoring
data or user-provided residue data. The
DEEM software itself is also used with CALENDEX,
an cumulative and aggregate exposure assessment
software application focusing on combined
dietary and (non-dietary) residential exposures.
By using appropriate toxicological parameters
associated with a chemical or constituent,
the analyses generated by DEEM express risk
as a function of dose received through the
dietary exposure route. To conduct either
chronic or acute risk analyses using DEEM
software the user must provide three types
of information:
(1) Concentrations of the
constituent in the foods and/or food-forms.
These can be a theoretical level such as
the tolerance or MRL (maximum residue limit)
or a level anticipated to be present in
the food of interest. The acute program
utilizes either a point estimate, a distribution
of residues, or a combination of both.
(2) Toxicological data on
the constituent that are directly relevant
to the evaluation of the significance of
estimates of exposure by the oral route.
These should include a toxicology endpoint
based on chronic (long-term) exposure such
as the cancer potency factor (Q1*), Acceptable
Daily Intake (ADI), chronic Population Adjusted
Dose (cPAD) or other chronic Reference Dose
(RfD). If acute exposures are to be evaluated,
an acute toxicological endpoint such as
the No Observed Effect Level (NOEL), acute
Population Adjusted Dose (aPAD) or acute
Reference Dose (aRfD) from a study in which
animals were dosed for short periods of
time will be required. The DEEM? software
will prompt the user for these values.
(3) Adjustment factors directly
relevant to potential constituent levels
in the diet to more accurately reflect likely
exposures. These adjustment factors can
include percent of the crop treated, percent
imported, impact of processing, etc.
DEEM expresses the potential
risk relative to either the chronic or acute
PAD, RfD (ADI) or NOEL (acute or chronic)
selected by the user. It also is capable
of expressing the exposure in relation to
the results of cancer studies. The slope
of the dose-response in cancer studies (called
the Q1*) is used to calculate a dose level
relevant to a chosen probability value from
a cancer study. Specifying the Q1* will
permit a calculation of the increased risk
of cancer due to long-term ingestion of
the chemicals and foods included in the
analysis.
As a crop item is processed
into foods, the constituents may preferentially
segregate into one fraction rather than
be distributed equally into the various
subparts of the item. For example, oil-soluble
surface residues may remain in the peel.
Thus, the residue level in peeled fruit
may be lower than in the whole, unpeeled
fruit. Similarly, the resulting concentration
in peanut oil may be higher than the concentration
in the whole peanut. To address this situation,
DEEM multiplies each food consumption estimate
by up to two “adjustment factors”
designed to allow better matching of the
residue data with food consumption data.
For example, raisin consumption is expressed
in terms of consumption of actual raisins.
If chemical residue measurements were made
on fresh grapes, an adjustment factor should
be applied to account for the chemical concentration
resulting from water loss. This adjustment
factor will more accurately estimate potential
residues in raisins. DEEM contains default
adjustment factors to equate processed food
consumption to equivalent fresh quantities.
A second adjustment factor may be used to
modify exposure estimates to reflect the
percentage of a crop that is expected to
contain residues (often called “percent
crop treated”). The user is allowed
to change any of these default adjustment
factors. A discussion of the default adjustment
factors is provided in Chapter 5 of the
DEEM
manual.
