Skip common site navigation and headers
United States Environmental Protection Agency
Exposure Research
Begin Hierarchical Links EPA Home > Research & Development > Exposure Research > Publications/Presentations > End Hierarchical Links

 

National Human Exposure Assessment Survey (NHEXAS): Analysis of Exposure Pathways and Routes for Arsenic and Lead in EPA Region 5

spacer
spacer
Abstract: The National Human Exposure Assessment Survey (NHEXAS) Phase I field study conducted in EPA Region 5 (Great Lakes Area) provides extensive exposure data on a representative sample of approximately 250 residents of the region. Associated environmental media and biomarker (blood, urine) concentration data were also obtained for the study participants to aid in understanding of the relationships of exposures to both contaminant pathways and doses. Besides fulfilling the primary NHEXAS objectives, the NHEXAS data provided an opportunity to explore secondary usages such as examining pathway to route of exposure relationships. A generic type of structural equation model was used to define the anticipated relationships among the various data types for both arsenic (As) and lead (Pb). Since, by design, only a few participants provided data for all sample types, implementing this model required that some media concentrations (outdoor air and soil) be imputed for subjects with missing information by using measurements collected in the same geographic area and time period. The model, and associated pairwise correlations, generally revealed significant but weak associations among the concentrations, exposures, and doses; the strongest associations occurred for the various air measurements (indoor versus outdoor and personal). The generally weak associations were thought to be partly due to the absence of complete coverage of non-residential environmental media and to non-synchonization of relevant measurement times and integration periods of collection across the various sample types. In general, relationships between the NHEXAS questionnaire data and the various concentration, exposure, and body-burden measures were also weak. The model results and the modeling exercise suggest several ways for optimizing the design of future exposure assessment studies that are aimed at supporting structural modeling activities.
spacer
Citation:Clayton, C. A., E. D. Pellizzari, and J. J. Quackenboss. National Human Exposure Assessment Survey (NHEXAS): Analysis of Exposure Pathways and Routes for Arsenic and Lead in EPA Region 5. JOURNAL OF EXPOSURE ANALYSIS AND ENVIRONMENTAL EPIDEMIOLOGY 12(1):29-43, (2002).
spacer
spacer
Contact: Liz Hope - (919) 541-2785 or hope.elizabeth@epa.gov
spacer
Division: Human Exposure & Atmospheric Sciences Division
spacer
Branch: Human Expsoure Research Branch
spacer
Product Type: Journal
spacer
Published: 01/01/2002
spacer
Related Entries:
spacer
Bullet Item Implement NHEXAS Analysis Strategy
spacer Relationship Reason:   A Project of the Product
spacer
spacer
spacer

 

ORD Home | Search EPA | Search NERL | Search EIMS | Contacts | Help

 
Begin Site Footer

EPA Home | Privacy and Security Notice | Contact Us

Last Updated on Monday, October 22, 2007
URL: http://cfpub.epa.gov