Model Keywords:
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), Area Source (e.g., spray, fertilizer, lagoon, holding area), Body Burden - Dose (e.g., phamacokinetics, retention, transformation), Pathway (e.g., inhalation, digestion, dermal, injection), Frequency and Duration, Location, Transformation (e.g., chemical reaction, partitioning, biodegradation), Transport (e.g., advection, bulk, dispersion, diffusion), Air, Ground (e.g., soil, sediment), Chemical (e.g., organic, inorganic, toxics),
Model Detail:
Model Evaluation
:Initial model evaluation has been conducted by comparing the modeled urinary metabolite concentrations against available measurement data from field studies (e.g., EOHSI/Rutgers residential chlorpyrifos study; NHEXAS Minnesota Children's Study). Although initial model evaluation has revealed that the model produces reasonable results compared to available measurements data, model evaluation will be ongoing as the model inputs and algorithms are refined and as new human exposure field measurements become available.
Conceptual, mathematical and chemical/physical verification has been performed by model developers. Peer reviewed publications on earlier version of the SHEDS-Pesticides model are available. The aggregate SHEDS-Pesticides chlorpyrifos case study was presented to and favorably reviewed by the ORD University Partnership Agreements peer consultation panel in 2002. Several iterations of sensitivity and uncertainty analyses have been conducted for the aggregate chlorpyrifos case study to identify key inputs and parameters influencing results. A scientific advisory panel specific for further evaluation and refinement of the SHEDS model is being planned.
An Aggregate Residential Exposure Model Comparison Workshop was conducted by ORD and OPP in October 2001 in which SHEDS-Pesticides was compared to other aggregate exposure models being developed (Lifeline, CARES, Calendex). The SHEDS results compared well to those of other models for the case studies considered.
Model Guidance Documents
:Currently not available.
Model Decision Documents
:Select publications describing the model:
1) Zartarian V.G., Ozkaynak H., Burke J.M., Zufall M.J., Rigas M.L., and Furtaw Jr. E.J. (2000). "A Modeling Framework for Estimating Children's Residential Exposure and Dose to Chlorpyrifos via Dermal Residue Contact and Non-Dietary Ingestion." Environmental Health Perspectives. 108(6): 505-514.
2) Zartarian V.G., Ozkaynak H., Xue J., 2001. "Assessing Residential Exposure Using the Stochastic Human Exposure and Dose Simulation (SHEDS) Model," International Society for Exposure Analysis (ISEA) Conference, Charleston, SC, November 2001.
Model Download Information
:Currently not available. The model is presently being refined and will be beta tested prior to its public release.
modelcontactinfo
:Dr. Valerie Zartarian
EPA/ORD/NERL/HEASD
Zartarian.valerie@epa.gov
617-918-1541
Dr. Haluk Ozkaynak
EPA/ORD/NERL
Ozkaynak.haluk@epa.gov
202-564-1531
Model Inputs
:CHAD time-location-activity diaries, pesticide usage information (e.g., amount per application and area, application method, time, and frequency), environmental concentrations and residues (air, soil, dust, food, surface residues), exposure factors (e.g., surface-to-skin residue transfer efficiency, frequency of hand-to-mouth contact, fraction skin surface area contacted), CSFII food consumption survey data, pharmacokinetic rate constants
Model Outputs
:Output options include individual daily exposure and dose time profiles, population cdfs, summary statistics tables, contributions by route and pathway, sensitivity analyses, and uncertainty analyses for predicted exposure, mass metabolite in blood, and mass metabolite eliminated in urine via the inhalation, dietary ingestion, dermal contact, and non-dietary ingestion routes, and also the absorbed and eliminated dose aggregated across all routes.
Model offers user the options for generating correlations, multiple regressions and uncertainty analysis using multiple stepwise regression analysis techniques to identify the variables and parameters that are most influential and those that contribute to greatest uncertainty in the predicted estimates.
Model Computer Requirements:
Model Operating Systems Needs
:Windows NT, Windows 2000, Windows XP
Model Hardware Needs
:PC Computer, at least 128 MB RAM, at least 500 MHz, at least 10GB hard drive, CD-ROM drive; faster processor and higher RAM recommended
Model Programming Language(s)
:SAS version 8 for PC including AF, Base, Stat, SASGraph, and Access (C++ prototype version available)
other_req
:User friendly GUI?s