Characterizing the relationship between biomarkers of exposure to volatile organic compounds and their environmental, demographic, and activity variables for the Great Lakes region
S.W. Wang1, R. Jornsten2, and P.G. Georgopoulos1
1Environmental and Occupational Health Sciences Institute, UMDNJ - R.W. Johnson Medical School and Rutgers University; 2Department of Statistics, Rutgers University
The formulation and application of a systematic data analysis framework is presented here. This framework has been designed to identify and characterize relationships among environmental, demographic, and activity variables in determining biomarker levels of exposure and was applied to study selected Volatile Organic Compounds (VOCs). This application involved the “meta-analysis” of data collected from two large-scale surveys, CDC’s NHANES-III and USEPA’s NHEXAS (Region-V). Specific objectives are (a) to determine the relative significance of ambient concentrations versus other exposure factors (e.g. demographic, time-activity variables) in predicting internal doses (e.g. biomarker levels) and (b) to identify vulnerable sub-populations experiencing unusual high exposures and associated contributing exposure factors. A systematic data analysis procedure is employed to the step-by-step resolution of challenges and limitations that exist in the NHANES-III and NHEXAS (Region-V) datasets; these challenges include missing values, collinearity, non-linearity, interaction effects etc., which were explored and resolved through graphical exploratory analysis, non-parametric exploratory analysis, and parametric multivariate multiple regression. Case studies include analyses of the biomarker levels of two aromatic compounds (benzene and toluene) and of the corresponding environmental, demographic, human activity, etc. data for selected populations in the Great Lakes region, where both NHANES-III and NHEXAS (region-V) surveys were conducted.
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.