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MULTIVARIATE ANALYSIS ON LEVELS OF SELECTED METALS, PARTICULATE MATTER, VOC, AND HOUSEHOLD CHARACTERISTICS AND ACTIVITIES FROM THE MIDWESTERN STATES NHEXAS
Citation:
Bonanno, L. J., N. G. Freeman, M. Greenberg, AND P. J. Lioy. MULTIVARIATE ANALYSIS ON LEVELS OF SELECTED METALS, PARTICULATE MATTER, VOC, AND HOUSEHOLD CHARACTERISTICS AND ACTIVITIES FROM THE MIDWESTERN STATES NHEXAS. APPLIED OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 16(9):859-874, (2001).
Impact/Purpose:
The NHEXAS analysis projects being conducted by NERL address the following scientific issues/questions:
- Do exposure distributions vary by demographic group?
- What is the impact of censoring (BDL) on multimedia distributions and associations?
- Which questionnaire/diary items are most useful in explaining variability or identifying "high exposure" groups?
- How do exposure classifications and measurements compare in their ability to explain variability in exposures and biomarkers?
- Can changes in exposures over time be explained by dietary and questionnaire/activity information?
- How well do NHEXAS findings compare with existing models/assessments (e.g., NATA)?
Description:
Microenvironmental and biological/personal monitoring information were collected during the National Human Exposure Assessment Survey (NHEXAS), conducted in the six states comprising U.S. EPA Region Five. They have been analyzed by multivariate analysis techniques with general household characteristics and activities that influence levels of residential exposure to contaminants. The aims of these analyses were to identify specific suites of characteristics and/or activities that indicate the presence of significant levels of multiple environmental contaminants in residences. Included were cadmium, chromium, arsenic, lead, inspirable particulate mass, 1,1,1-trichloroethylene, p-dichlorobenzene, benzene, chloroform, styrene, tetrachloroethylene, toluene, trichloroethylene, m,p-xylene, and o-xylene, and many were measured in multiple media. Residential characteristics and activities were collected using multiple survey instruments. A suite of factor analysis results for level of environmental contamination in residences yielded gasoline, metals in dust and dust mass, solvents, and tobacco smoke as proximate and ultimate residential sources. The analyses on household characteristics identified factors for suburban-type homes, rural homes, older homes, and dilapidated homes. The analyses using residential activity variables yielded factors for the sources gasoline and combustion, and for the activities of construction, cleaning, and cooling. Discriminant analysis linked the volatile organic compounds in the residences to the storage of gas-powered devices that were in the home or attached garage, the use of mothballs, and to the presence of carpets. Residential metals were linked to the presence of chipping paint, window replacement, and smoking, and appeared to classify 33 percent of the participants. Construction and cleaning activities in the home were associated with the potential for elevated levels of particulate mass in the air and on the floor or carpet, and p-dichlorobenzene in indoor air. These classified 50 percent of the participants above. Dilapidated homes and suburban-type homes were associated with specific metals and/or VOC, and the analysis, again, classified about 50 percent of the participants. In some cases multimedia activities classified individual participants. A combination of factor analysis and discriminant analysis demonstrated that residential characteristics and activities can be used as predictors of the presence or absence of VOC and of metals in the residence.
This article has not been subjected to review by the U.S. Environmental Protection Agency. The views and opinions expressed are solely those of the authors and do not necessarily reflect the views or policies of the agency.