 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

Office of 

Prevention, Pesticides and 

Toxic Substances

	

		                                                                      
                 Office of Prevention, Pesticides 

DATE:  July 11, 2007

MEMORANDUM

Subject:  Transmission of Background Materials for the August 14-15,
2007 FIFRA Scientific Advisory Panel Entitled “Review of
EPA/ORD/NERL’s SHEDS-Multimedia Model, Aggregate Version 3”

To:  		Melissa Kramer, Designated Federal Official

FIFRA SAP

Office of Science Coordination and Policy

From:  	Dana Vogel

Office of Pesticide Programs

Health Effects Division (7509PY)

Through:	Tina Levine, Ph.D., Director

Office of Pesticide Programs

Health Effects Division (7509PY)

Attached please find the first set of background materials (1 of 2) and
related charge questions for the August 14-15, 2007 FIFRA Scientific
Advisory Panel entitled “Review of EPA/ORD/NERL’s SHEDS-Multimedia
Model, Aggregate Version 3.”    SEQ CHAPTER \h \r 1 The purpose of
this 2-day meeting is to request:

(1) a formal model review by the SAP on the Stochastic Human Exposure
and Dose Simulation for Multimedia, Multipathway Pollutants
(SHEDS-Multimedia), aggregate version 3 (residential module); 

(2) a peer consultation by the SAP on planned methodologies to extend
SHEDS-Multimedia version 3 to version 4; and

(3) a peer consultation by the SAP on the SHEDS-Multimedia dietary
module that will also be incorporated into SHEDS-Multimedia version 4.

This SAP review is part of the Agency’s ongoing process to enhance
probabilistic risk assessments and OPP’s ongoing efforts to address
safety standards of the Food Quality Protection Act (FQPA) of 1996. 
FQPA amended the laws under which EPA evaluates the safety of pesticide
residues in food.  Section 408(b)(2)(D)(v) and (vi) of the Federal Food
Drug and Cosmetic Act, as amended by FQPA, specifies that when
determining the safety of a pesticide chemical, EPA shall consider
aggregate exposure (i.e., total dietary (food and water), residential,
and other non-occupational) and available information concerning the
cumulative effects to human health that may result from exposure to
other substances that have a common mechanism of toxicity.  

SHEDS-Multimedia can address many useful aspects of aggregate and
cumulative risk assessment related to population aggregate exposures for
different multimedia chemicals and the important contributing pathways
and factors.  Such information will be useful in identifying populations
and exposure scenarios of greatest concern for this class of chemicals. 
These populations and exposure scenarios will in turn be used to
determine the most relevant chemical/pyrethroid combinations for which
hazard/exposure factors information will need further development in
order to support a PBPK dose modeling approach.  EPA plans to extend the
current single chemical aggregate version (version 3) of SHEDS to
version 4, a cumulative (multi-chemical) version that will include both
the residential and dietary modules, i.e., estimate both residential and
dietary exposures for simulated individuals.  The cumulative version of
SHEDS, which will also include enhancements to version 3 to be reviewed
by the August 14-14, 2007 SAP, will be used to estimate cumulative
exposure to pyrethroid pesticides. Agency staff from ORD/ NERL are
collaborating with the Office of Pesticide Programs (OPP) on development
and application of the various modules for the SHEDS-Multimedia version
4 model. 

  SEQ CHAPTER \h \r 1 To assist the August 14-15, 2007 FIFRA SAP in
their review of the SHEDS-Multimedia version 3 (aggregate residential)
model, each FIFRA SAP member will be provided CD(s) containing a
technical report describing the SHEDS-Multimedia version 3 model,
annotated SHEDS code with a graphical user interface, and a user guide
for the graphical user interface.  Below are the related charge
questions for this portion of the SAP meeting.    Three issues will be
presented for the FIFRA SAP review of the SHEDS-Multimedia version 3. 
The materials and related charge questions for Issue 1 are detailed
below.  Separate materials and charge questions will be provided
subsequently to the SAP for Issue 2 (version 4 planned methodologies)
and Issue 3 (SHEDS-dietary module).

I.  Charge Questions Related to the Review of EPA/ORD/NERL’s
SHEDS-Multimedia Model, Aggregate Version 3

Issue 1:  Documentation, completeness, and clarity of the technical
aspects and usability of the SHEDS-Multimedia version 3 (aggregate
residential) model 

Question 1:  The SHEDS-Multimedia version 3 User’s Manual provided to
the SAP presents installation and operational instructions for the
software. 

a)  Were Panel members able to load the software on to their computers?
What, if any, difficulties were encountered in loading or running the
software? 

b)	The SHEDS-Multimedia version 3 graphical user interface (GUI) was
designed to be user-friendly to exposure modelers and risk assessors. 
Please comment on the organization and usability of the GUI, any
difficulties you encountered, which features and output capabilities
were most useful, and whether any additional options would be helpful. 
Please also comment or offer suggestions for improving the GUI/model
interface.

 c) 	Please comment on the organization, clarity, completeness, and
usefulness of the User Guide document and provide any suggestions for
improvement.

Question 2:  The SHEDS-Multimedia version 3 Technical Manual provided to
the SAP provides an overview of the SHEDS-Multimedia aggregate
residential model; presents  detailed descriptions of key model
components; and describes the model construct and algorithms, required
inputs, and analysis/output capabilities.  

a)	Please comment on whether the descriptions of specific model
components are scientifically sound and whether the algorithms described
in the Technical Manual represent the state of the science for
performing exposure assessments.   Please also comment or offer
suggestions for improving or modifying these algorithms or other aspects
of the model construct.

b)	Please comment on the organization, clarity, completeness and
usefulness of the Technical Manual and provide any suggestions for
improvement.

Question 3: The Source Code Directory on the CD provided to the SAP
includes annotated code for the exposure algorithms used in the
SHEDS-Multimedia aggregate residential model.  

Please comment on whether the annotated code is sufficiently clear such
that the algorithms can be followed and understood.  

Please also comment on whether these algorithms are technically correct
and consistent with the descriptions provided in the technical manual. 

II. List of Attachments for SHEDS-Multimedia version 3 Residential
Module Review:

Installation Instructions for the SHEDS-Multimedia version 3 (aggregate
residential) model (filename:  SHEDS_Multimedia_Installation.doc)

SHEDS-Multimedia version 3 (aggregate residential) model (installation
for code review and running/testing model with graphic user interface)(
filename:  SHEDS_Multimedia_Setup_3.14c.exe)

SHEDS-Multimedia version 3 (aggregate residential) model Users Guide
(filename:  SHEDS-Multimedia3_UsersGuide_06_13.pdf)

SHEDS-Multimedia version 3 Technical Manual (filename: 
SHEDS_TechManual_06-14.pdf)

