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US EPA'S SUPERSITES PROGRAM
Citation:
Solomon, P A., R. D. Scheffe, AND M. Pitchford. US EPA'S SUPERSITES PROGRAM. Presented at Real World 2000, Clean Air Conference, Atlanta, GA, May 15-18, 2000.
Impact/Purpose:
The PM Supersites Program is an ambient monitoring program intended to address the scientific uncertainties associated with fine particulate matter. The main objectives of the Supersites Program are as follows: 1) characterize particulate matter in a way that contributes to the understanding of source-receptor relationships and supports development of State Implementation Plans (SIPs), 2) develop and test advanced measurement methods for potential use in national monitoring networks, and 3) support health and exposure studies by providing detailed chemical and physical data at one or more central monitoring sites.
The specific objectives of this task are to provide scientific review and coordination of the technical aspects of the Supersites Program. This includes coordination among all Supersites projects and other projects which support Supersites objectives, overseeing of the data management, and coordinating the communication of data analysis and modeling results to the scientific community and other stakeholders. Products include a number of peer-reviewed journal articles (approaching 200 or more), final reports from each project, a relational database than includes not only Supersites data, but most aerometric data collected in the continental US and SE Canada during the period July 2001 to August 2002, and a policy relevant findings synthesis entitled Key and Policy Relevant Findings from the Supersites Program and Related Studies. Also supporting the synthesis is a major international conference where results will be presented from air quality methods, measurements, modeling, and data analysis studies with similar objectives to the Supersites program and during the time period of the Supersites Program, i.e., the last 5-7 years.
Description:
Dermal exposure to volatile organic compounds (VOCs) in water results from environmental contamination of surface, ground-, and drinking waters. This exposure occurs both in occupational and residential settings. Compartmental models incorporating body burden measurements have been developed to estimate VOC exposure through pathways of inhalation and ingestion. This modeling approach is needed for the dermal pathway as well because VOC dermal exposure in water can be significant. We present preliminary results of alveolar breath measurements as a biomarker for VOC dermal exposure. Models were developed from VOC dermal uptake and breath concentration measurements collected in a laboratory-based human in vivo study. Subjects placed their hand and forearm into a sealed 2-liter plexiglass cylinder containing 100, 100, 100, and 400 g/L of chloroform, toluene, 1,1,1-trichloroethane (111TCA) and methyl t-butyl ether (MTBE) in water, respectively, for one hour. The amount of dermal uptake was determined by measuring the change in water concentration from the beginning to the end of the exposure period. Concentrations of target VOCs in breath were measured before, during and after exposure in order to establish the concentration time-course associated with dermal uptake. Breath samples were collected via a single-breath exhalation procedure into Summa canisters. Breath sample analysis was conducted using a gas chromatography/mass spectrometry detector (GC/MS). This study develops mathematical, compartmental models to estimate VOC dermal exposure with body burden as a biomarker. This modeling approach is an effective and practical tool for held researchers to more fully characterize the population exposure distribution.
This study has been supported in part by the United States Environmental Protection Agency. It has been subjected to Agency review and approved for publication.