Citation:

Junod, N., J. C. Chuang, AND J M. Van Emon. AN APPROACH TO METHODS DEVELOPMENT FOR HUMAN EXPOSURE ASSESSMENT STUDIES. Presented at 223rd American Chemical Society National Meeting, Orlando, FL, April 7-11, 2002.

Impact/Purpose:

The overall objectives of the task include several components: (1) develop immunochemical methods for compounds difficult to analyze by conventional methodologies; (2) tailor immunochemical methods to support specific human exposure assessment studies; (3) team immunochemical sample preparations with instrumental analysis such as mass spectrometry for in-depth sample characterization; (4) provide methods to support NERL's human exposure and environmental monitoring efforts; (5) provide analytical methods that improve risk assessments by reducing the amount of uncertainity in environmental measurements; (6) provide multimedia analytical methods to support an integrated multimedia approach to assess and characterize risk to human health and the environment; (7) provide sponsorship of annual immunochemistry research meetings as a forum for stimulating interest and discussion on current or emerging bioanalytical methods; (8) develop and incorporate rapid, cost-effective laboratory and field portable immunochemical techniques such as enzyme-linked immunosorbent assay (ELISA) methods into monitoring studies and human exposure field surveys to delineate sub-populations of "highly exposed" individuals for detailed follow-up studies.

Specific method needs have been identified through consultations with client office personnel. This Task strives to fulfill those needs as appropriate. In particular, methods for pyrethroids, e.g., permethrin, cypermethrin, and deltamethrin are being developed and evaluated. Efficient sample preparations are under development for exposure samples using pressurized liquid extraction. Confirmation will be achieved using high performance liquid chromatography (HPLC). A rapid immunoassay approach for the analysis of 2,4-D in urine will be completed and a SOP and report written. Immunoaffinity chromatography sample preparations for the pyrethroids will be developed. Work will continue on the application of antibody replacements such as molecularly imprinted polymers. Additional candidate analytes will be identified for a tiered approach and to guide development of the next Task. Flexibility will be maintained to address methods and measurement issues as they arise during the task period which ends in FY06. The objective of the Task is to develop bioanalytical methods to support exposure monitoring studies during the task period.

Description:

Human exposure assessment studies require methods that are rapid, cost-effective and have a high sample through-put. The development of analytical methods for exposure studies should be based on specific information for individual studies. Human exposure studies suggest that dietary ingestion is an important pathway for exposure to pesticides. Our approach for determining the need for new methods for a dietary exposure study was based on three key areas. An overview of the diets of the American population was developed and classified by age group, based on information from specialized databases such as the U.S. Department of Agriculture's food consumption surveys. Next, we reviewed more than 60 papers, involving 250 pesticides, on existing analytical methods for measuring pesticide residues in food, including both conventional and immunoassay techniques. Finally, we examined 50 papers describing current conventional and immunoassay methods for the determination of pesticide biomarkers in urine. This information was compiled and is being used to direct methods development in support of dietary exposure studies.

This work has been funded wholly or in part by the U.S. Environmental Protection Agency. It has been subjected to Agency review and approved for presentation. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

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