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HUMAN EXPOSURE ASSESSMENT USING IMMUNOASSAY
Citation:
Van Emon, J M., W C. Brumley, A W. Reed, AND J. C. Chuang. HUMAN EXPOSURE ASSESSMENT USING IMMUNOASSAY. Presented at American Chemical Society 221st National Meeting, Immunochemistry Summit IX Symposium, San Diego, CA, April 1-5, 2001.
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:
The National Exposure Research Laboratory-Las Vegas is developing analytical methods for human exposure assessment studies. Critical exposure studies generate a large number of samples which must be analyzed in a reliable, cost-effective and timely manner. TCP (3,5,6-trichloro-2-pyridinol) is a urinary metabolite and environmental degradation product of the insecticide chlorpyrifos (O,O-diethyl-O-[3,5,6-trichloro-2-pyridyl]-phosphorothioate). Enzyme-linked immunosorbent assays (ELISAs) have been developed and evaluated to detect low-level TCP in food and urine. Samples from dietary exposure studies and human exposure surveys were analyzed by the ELISA and gas chromatography/mass spectrometry (GC/MS). The limit of detection for the ELISA is 0.1 ppb in diluted food and hydrolyzed urine extracts. Comparative studies with GC/MS indicate a good correlation between the two methods for low ppb levels. Samples from occupational and nonoccupational exposure studies yielded correlations of r=0.990 and r=0.970, respectively.
This work has been funded wholly or in part by the U.S. EPA under Contract 68-D99-011 Battelle. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.