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ANALYSIS OF HOUSEHOLD WATER USE BEHAVIOR FOR USE AS IAQ MODEL PARAMETERS
Citation:
Wilkes, C. R., S C. Hern, AND A. D. Mason. ANALYSIS OF HOUSEHOLD WATER USE BEHAVIOR FOR USE AS IAQ MODEL PARAMETERS. Presented at Indoor Air 2002, Monterey, CA, June 30-July 5, 2002.
Impact/Purpose:
Research will be conducted to develop and apply integrated microenvironmental, and physiologically-based pharmacokinetic (PBPK) exposure-dose models and methods (that account for all media, routes, pathways and endpoints). Specific efforts will focus on the following areas:
1) Develop the Exposure Related Dose Estimating Model (ERDEM) System.
Includes: Updating the subsystems and compartments of the ERDEM models with those features needed for modeling chemicals of interest to risk assessors;
Designing and implementing the graphical user interface for added features.
Refining the exposure interface to handle various sources of exposure information;
Providing tools for post processing as well as for uncertainty and variability analyses;
Research on numerical and symbolic mathematical/statistical solution methods and computational algorithms/software for deterministic and stochastic systems analysis.
2) Apply ERDEM and other quantitative models to understand pharmacokinetics (PK) and significantly reduce the uncertainty in the dosimetry of specific compounds of regulatory interest.
Examples of the applications are:
exposure of children to pesticides
study design
route-to-route extrapolation
species extrapolation
experimental data analysis
relationship between parametric uncertainty and the distribution of model results
validity of scaling methods within species
validity of scaling methods from one species to another species
reduction of uncertainty factors for risk assessment
Description:
Chemicals brought into the home through the domestic water supply, result in human exposure via the three principal routes: ingestion, inhalation, and dermal contact. Disinfection byproducts resulting from the treatment of municipal water supplies lead to the formation of a mixture of organic compounds ranging from high to low volatility. The inhalation route has been shown to be the most significant route of exposure for the more volatile chemicals.
In assessing exposure to indoor air contaminants, understanding population water-use behavior for indoor water-use activities as a function of demographic characteristics is vital to realistic exposure estimates. Currently, there are few and limited studies that analyze household water-use behavior; the leading resources are summarized in the Exposure Factors Handbook (U.S. EPA, August 1997). In response to the need for more specific and usable population based water-use data to be used as inputs for exposure modeling, new data sources have been analyzed. Frequencies and durations of use of showers, baths, clothes washers, dishwashers, toilets and faucets are presented and compared for various demographic groups derived from analyses of the National Human Activities Pattern Survey (NHAPS) database, the Residential End Uses of Water Study (REUWS) database, the Residential Energy Consumption Survey (RECS) as well as from current literature and manufacturer information. Volumes and flowrates are also analyzed from REUWS for the various water uses. Distribution parameters for water use behaviors of various sub-population groups are identified for water uses to be used as inputs for modeling of exposure to water borne contaminants.
The results from the database analyses will be presented in the form of fitted distributions for water-use durations for the various sub-population groups. A summary of frequency of use parameters for all water uses, and volume and flowrate characteristics of clothes washers and dishwasher appliances are also presented.
This work has been funded wholly or in part by the United States Environmental Protection Agency and has been approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.