Modeling cumulative and aggregate exposures of co-occurring multimedia contaminants in a probabilistic source-to-dose framework
P.G. Georgopoulos1, S. Isukapalli1, S-W. Wang1, Y-C. Yang1, V. Zartarian2, J. Xue2 and H. Ozkaynak2
1Environmental and Occupational Health Sciences Institute, UMDNJ - R.W. Johnson Medical School and Rutgers University; 2National Exposure Research Laboratory (NERL), USEPA
An assessment of cumulative and aggregate exposures of co-occurring multimedia contaminants, focusing on arsenic and trichloroethylene (TCE) exposures is presented for the general population of USEPA Region-V, is presented. This study employs a probabilistic source-to-dose modeling framework of the MENTOR/SHEDS-4M system [Modeling ENvironment for TOtal Risk studies (MENTOR) that uses the Stochastic Human Exposure and Dose Simulation (SHEDS) approach for Multiple co-occurring contaminants and Multimedia, Multipathway, Multiroute exposures (4M)]. Evaluation data have been extracted from the NHEXAS Region V database of field measurements. The MENTOR/SHEDS-4M combines microenvironmental and human activities characterization to assess the relative contribution of (1) media (e.g., water, food, dust), (2) pathways (e.g., drinking water, diet, hand-to-mouth) and (3) routes (e.g., oral, inhalation, dermal) to (4) multiple contaminant (e.g. VOCs and heavy metals) exposures for individuals or populations. It addresses aggregate and cumulative exposures to co-occurring pollutants in a consistent manner, and provides the ability to focus on mechanism-relevant time scales and subpopulations of interest. It also proceeds a major step further, to calculate target tissue dose (and corresponding biomarker levels) employing Physiologically Based Pharmacokinetic (PBPK) modeling. This offers the advantage of allowing model evaluation against field measurements. Biomarker data in the NHEXAS Region-V database have been used to evaluate the performance of the MENTOR/SHEDS-4M system.
This work had been funded in part by the US Environmental Protection Agency under Cooperative Agreement # EPAR-827033 to the Environmental and Occupational Health Sciences Institute (EOHSI). The viewpoints expressed here are the responsibility of the authors and do not necessarily reflect the views of the USEPA or its contractors.