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LESSONS LEARNED FROM THE NATIONAL HUMAN EXPOSURE ASSESSMENT SURVEY (NHEXAS)
Citation:
Leovic, K W., L S. Sheldon, K W. Thomas, V R. Highsmith, N S. Tulve, G L. Robertson, K. Hammerstom, J J. Quackenboss, L J. Melnyk, M Berry, E. Pellizari, M. Lebowitz, AND P. B. Ryan. LESSONS LEARNED FROM THE NATIONAL HUMAN EXPOSURE ASSESSMENT SURVEY (NHEXAS). Presented at International Society of Exposure Analysis 2002 Conference, Vancouver, Canada, August 11-15, 2002.
Impact/Purpose:
The overall objectives of this task are to
1) conduct analyses of the NHEXAS data for description of data quality and aggregate exposures;
2) review, summarize, and organize the NHEXAS questionnaire and analytical results databases, and
3) collect and record the experiences and recommendations of the study investigators and staff regarding key lessons which were learned in conducting these studies.
Description:
Three NHEXAS Studies were conducted from 1995-1997 to evaluate total human exposure to multiple chemicals on community and regional scales. EPA established cooperative agreements with three Consortia to conduct three interrelated NHEXAS field studies. The University of Arizona, Battelle Memorial Institute, and the Illinois Institute of Technology studied several hundred Arizona residents. Several hundred participants from EPA Region 5 were studied by Research Triangle Institute and the Environmental and Occupational Health Sciences Institute. In a third study, Harvard University, Johns Hopkins University, Emory University, Southwest Research Institute, and Westat studied 80 Maryland residents. Interagency Agreements were established with the Centers for Disease Control and Prevention, the Food and Drug Administration, and the National Institute for Standards and Technology for biomarker and environmental analyses. Volunteer participants were randomly selected from each of three areas of the country to obtain a population-based probability sample. Scientists measured the levels of a suite of chemicals to which participants were potentially exposed in air, foods, beverages, soil, and dust. Measurements were made of chemicals or their metabolites in biological samples, including blood and urine. Participants completed questionnaires to help identify possible sources of exposure and to characterize themselves, their activity patterns, and the home environment. As a follow-up to the NHEXAS Studies, a Workshop was held in 2001 to: 1) document the experiences and lessons learned for use in designing and implementing future studies; 2) assess the feasibility of approaches for conducting NHEXAS-type studies and measurements on representative samples of the population and subpopulations; and 3) assess the adequacy of methods, approaches, and designs to collect data for multiple pathways/routes of exposures for multiple pollutant classes. Participants included individuals from the Consortia, EPA, and other federal agencies. Extensive interviews were conducted with participants before the Workshop to help serve as a basis for discussion. Highlights of lessons learned, as discussed at the Workshop, include:
Large-scale population-based exposure studies can be planned, designed, coordinated, resourced, and logistically implemented.
Relevant exposure samples and corresponding metadata can be collected to characterize aggregate exposures for key species for selected ages and lifestyles.
The scientific community (federal agencies, universities, states, communities, contractors) can work together efficiently and effectively to plan and conduct studies.
High percentages of samples can be successfully collected and analyzed for most media.
Cooperative agreements can be appropriate funding mechanisms to support research.
The extensive documentation developed and evaluated (e.g., Standard Operating Procedures, methods, databases) will be very useful for designing and conducting field studies.
Results will be useful to develop future hypotheses and answer many current science issues.
Lessons learned and areas for improvement in project leadership, study design, survey operations, field sampling, analytical laboratories, database issues, and quality assurance will be presented, along with recommendations for future studies.
This work has been funded wholly by the U.S. EPA under contracts with University of Arizona (1D-5008NATX, 1D5010-NATX, 0D-5929-NATX), Battelle Memorial Institute (0D-5928-NANX), Research Triangle Institute (1D-5015-NANX), Environmental and Occupational Health Sciences Institute (0D-5925-NATX), Emory University (1D-5013-NAEX), Southwest Research Institute (0D5927-NANX), and Westat (1D-5012-NALX). It has been subjected to Agency review and approved for publication.