Modeling exposures to VOCs through the Individual-based exposure modeling implementation of MENTOR/SHEDS-1A
S.W. Wang, X. Tang, N. Lahoti, S. Tong, S. Isukapalli, P.G. Georgopoulos
Environmental and Occupational Health Sciences Institute, UMDNJ - R.W. Johnson Medical School and Rutgers University, Piscataway, NJ
A source-to-dose modeling study of exposures to VOCs is presented for the subjects of the three sample populations (Elizabeth, NJ; Houston, TX; Los Angeles, CA) studied in the “Relationships of Indoor, Outdoor and Personal Air” (RIOPA) project (Weisel et al., 2005). This work employs the Individual-Based Exposure Modeling (IBEM) implementation of the MENTOR/SHEDS-1A [Modeling ENvironment for TOtal Risk studies (MENTOR) using the Stochastic Human Exposure and Dose Simulation (SHEDS) approach in a "One Atmosphere" (1A) setting]. MENTOR/SHEDS-1A characterizes cumulative exposures to co-occurring air pollutants and calculates exposure and dose profiles, while providing the ability to focus on time scales and individuals/populations of interest. The MENTOR/SHEDS-1A application in the present study consists of following steps: (1) Characterization of background concentrations of contaminants through a combination of environmental model predictions and field data; (2) Estimation of local outdoor levels of contaminants through application of a local scale air quality model such as ISCST3, AERMOD, etc.; (3) Characterization of individual subjects attributes (age, gender, race, income, etc.); (4) Development of activity event sequences for each individual of the study for the exposure period; (5) Estimation of levels and temporal profiles of contaminants in various microenvironments; (6) Calculation of personal exposure concentrations by combining activity diaries with the modeled microenvironmental concentrations. Case studies simulating individual exposures to selected VOCs (Benzene, Formaldehyde, TCE, and PERC) are presented for the adult study subjects in the three RIOPA cities.
The present work has been funded by the American Chemistry Council (ACC - Research Agreement 2488) and the U.S. Environmental Protection Agency (USEPA – Cooperative Agreement CR-83162501). The viewpoints expressed in this work are solely the responsibility of the authors and do not necessarily reflect the views of ACC and USEPA, or their contractors.