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DERMAL AND MOUTHING TRANSFERS OF SURFACE RESIDUES MEASURED USING FLUORESCENCE IMAGING
Citation:
Nishioka, M. G., E A. CohenHubal, W. Ivancic, K. Andrews, AND J. Sowry. DERMAL AND MOUTHING TRANSFERS OF SURFACE RESIDUES MEASURED USING FLUORESCENCE IMAGING. Presented at 11th Annual Meeting of the International Society of Exposure Analysis, Charleston, SC, November 4-8, 2001.
Impact/Purpose:
1. To identify those pesticides, pathways, and activities that represent the highest potential exposures to children;
2. To determine the factors that influence pesticide exposures to children;
3. To develop methods for measuring multimedia exposures to children, including methods that account for important activities that take place in home, school, and day care settings;
4. To generate data on multimedia pesticide concentrations, pesticide biomarkers, and exposure factors that can be used as inputs to aggregate exposure models for children.
Description:
To reduce the uncertainty associated with current estimates of children's exposure to pesticides by dermal contact and non-dietary ingestion, residue transfer data are required. Prior to conducting exhaustive studies, a screening study to develop and test methods for measuring residue transfers and to identify the important parameters for characterizing these transfers was conducted.
Two different quantitative fluorescence measurement techniques were developed so that dermal and mouthing contact transfers could be assessed with a non-toxic surrogate for pesticides. Contact/mouthing surfaces included nylon carpeting, laminate flooring, and toys. These surfaces were sprayed with highly fluorescent riboflavin (water-soluble Vitamin B2) at levels approximating post-application pesticide residue levels, and allowed to dry completely before dermal or mouthing contact experiments.
The first method, quantitative video fluorescence imaging analysis, was developed for in-situ measurement of trace levels of riboflavin on hands following contact with the carpet or laminate surface. Subjects (n=3) contacted these surfaces with one of 24 combinations of contact parameters, including duration, pressure, and skin moisture. Overall, transfer for initial contact averaged 2.6% and transfer for multiple contacts averaged 6.3%. Hand washing removed 30-90% of residues; contacting a clean surface removed <15%.
The second method, involving extraction and spectrofluorimetry analysis, was developed to measure the trace levels of riboflavin removed from the surface of a treated toy by a simulated mouth that consisted of polyurethane foam (PUF) strips wrapped around three fingers and moistened with a surrogate saliva. Subjects (n=3) "mouthed" hard, soft and plush toys with one of 24 combinations of contact parameters, including pressure, duration and mouthing motion. Overall, transfers averaged 48%, with a low of 10-20% for mouthing plush toys, and a high of 100% for sucking on hard toys.
Experiments were also conducted to assess relative transfers of riboflavin and the pesticides chlorpyrifos and allethrin from treated carpet and laminate surfaces to transfer sampling devices that rely on either a polyurethane foam sleeve (the PUF Roller) or an Empore C18 disk (the Press Sampler). From carpets, transfer efficiencies for chlorpyrifos and riboflavin were similar, ~0.3% with the PUF Roller and ~0.04% with the Press Sampler. From laminates, riboflavin transfer was about 10X higher than chlorpyrifos transfer, with transfer to PUF of ~2% and transfers to C18 of ~1%. Further work is being conducted to better characterize the relationship between transfer of tracer and pesticides.
This work has been funded wholly or in part by the United States Environmental Protection Agency under contract No. 68-D-99-011 to 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.