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August 2007 FIFRA Scientific Advisory Panel Recommendations for SHEDS-Dietary and SHEDS-Residential Modules (Summarized) and EPA Responses
Citation:
XUE, J., V. G. ZARTARIAN, S. NAKO, AND D. MILLER. August 2007 FIFRA Scientific Advisory Panel Recommendations for SHEDS-Dietary and SHEDS-Residential Modules (Summarized) and EPA Responses. U.S. Environmental Protection Agency, Washington, DC, EPA/600/S-10/004, 2010.
Impact/Purpose:
The National Exposure Research Laboratory′s (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA′s mission to protect human health and the environment. HEASD′s research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA′s strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.
Description:
Over the past ten years, the Agency has requested the Panel to review several probabilistic dietary exposure software models. These have included DEEM-FCID™, Calendex-FCID, CARES™, LifeLine™, and an earlier (specialized) version of SHEDS (SHEDS-Wood) designed to assess exposures and doses of wood preservatives. SHEDS-Wood was presented to the Panel on August 28, 2002 and December 3-5, 2003, and focused on children's dermal and non-dietary ingestion exposure to chromated copper arsenate (CCA) on treated decks and play sets. In August 2007, SHEDS-Multimedia version 3 underwent review by FlFRA SAP. This earlier version of SHEDS was an aggregate (single chemical) version that was able to assess residential post-application exposures. During that SAP, a conceptual approach to a planned dietary module for SHEDS-Multimedia was also presented to and reviewed by the Panel. At that time, the Agency directed a number of questions to the Panel regarding usability and potential improvements to the SHEDS-Multimedia residential module, as well as approaches to assessing dietary exposures, which would be coded into SAS and SHEDS in a future version. At this 2007 SAP, the Panel stated that it was generally "impressed with the current version of the SHEDS model and future plans for the model..." (SAP 2007, p.1 0), that "the model algorithms appear to be technically correct... [and that] the code is clear enough that the algorithms can be easily followed" (SAP 2007, p.10). In addition, the Panel stated that "the GUI is helpful and straightforward, but ... could be improved by adding context specific information that is clearly available at all times" (SAP 2007, p.10). As part of its report, the Panel did have a number of suggestions on the organization, clarity, completeness, and usefulness of the model manuals. Since that time, Agency staff from the Office of Pesticide Program (OPP) and the Office of Research and Development (ORD)'s National Exposure Research Laboratory (NERL) have continued to collaborate to develop and code the dietary module for the SHEDS-Multimedia software and to improve and update the residential module considering the Panel's 2007 suggestions. These efforts were geared toward producing a SHEDS-Multimedia Version 4.0 model, with both a residential and dietary module, that could be used to conduct an aggregate (single chemical) exposure assessment for a pesticide or other multimedia chemical, or a cumulative (multi-chemical) exposure assessment. To date, this collaborative effort between ORD and OPP has produced separate SHEDS-Dietary and SHEDS-Residential exposure assessment software programs, each of which address a number of the 2007 Panels’ ideas and concerns relating to user interface, algorithms, usability, utility, and documentation. The current (2010) SAP is being requested to review each of these two models, which are considered as modules of SHEDS-Multimedia version 4, and a proposed approach to merge them (i.e., calculate dietary and residential exposure for the same simulated individual after food consumption and activity pattern diaries are appropriately matched) for the next iteration of SHEDS-Multimedia. The purpose of this background document is to recap and summarize for the current (2010) Panel the earlier 2007 comments and to provide the Agency's response to them. It is divided into two sections, with the first relating to the dietary module and the second relating to the esidential module. These sections highlight research and development on the SHEDS-Multimedia dietary and residential modules that has occurred since the 2007 SAP; it is hoped that this document provides some background and context with respect to the Agency's continuing activities and efforts aimed at advancing SHEDS in particular. and exposure science in general, and that it will assist the Panel in its current deliberations.