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PESTICIDE SURFACE RESIDUE MEASUREMENTS BY A PRESS SAMPLER
Citation:
Melnyk, L J., C. Rohrer, T Hieber, AND M R. Berry Jr. PESTICIDE SURFACE RESIDUE MEASUREMENTS BY A PRESS SAMPLER. Presented at ISEA Annual Meeting, Charleston, NC, November 4-8, 2001.
Impact/Purpose:
The purpose of this research is to reduce uncertainties in exposure assessments of young children by improving EPA's ability to measure exposures in the context of aggregate and cumulative exposure assessments. The general objective of this research is to support FQPA children's exposure assessment efforts by improving procedures and reducing uncertainty in measurements for dietary exposure of young children, a critically needed area for improved risk assessment. Specifically, this research will evaluate a protocol and companion model for measuring or otherwise assessing the combined dietary intake of a young child as influenced by pesticides, or other environmental contaminants, which contaminate their foods during the eating process (indirect ingestion exposure). This research will continue to develop the important factors which are needed to characterize excess intake of pesticides by young children. Specifically, the research will measure pesticide surface transfer efficiencies for food contacts with surfaces and eating activity patterns of young children that define the frequency of contacts with contaminated surfaces. A series of reports/products are anticipated by the end of FY05.
Description:
Pesticides on household surfaces are a source of exposure to children. Accurate measurements of residues on surfaces are needed to determine amounts available for transfer to foods and other objects handled or eaten by a child. Wiping the surface with a solvent has been the acceptable measurement method, but sing solvents can mar the surface which would be unacceptable for field sampling. A surface press sampler capable of using C18 or polyurethane foam (PUF) transfer disks pressed onto a surface for a specified time with constant force was compared to surface wipe measurements. The transfer disks, which adsorb and/or absorb the residue during contact of the surface, are then removed and extracted for analysis and quantified for surface residue concentration or loading.
The objective of this study was to determine if the surface press sampler with dry C18 and PUF disks could be used to obtain residue information from household surfaces comparable to isopropanol surface wipes. The surfaces tested were ceramic tile, hardwood flooring, and carpet. Each surface was contaminated with an aqueous solution of the pesticides commonly found in homes (diazinon, malathion, chlorpyrifos, isofenphos, heptachlor, and cis- and trans- permethrin) at levels previously measured (20 to 55 ng/cm2) and dried for 2-1/2 hours. Duplicate contaminated surfaces were wiped and pressed for 5 sec, 1, 2, 5, 10, and 60 min and percentages of pesticides transferred based on wipes were compared.
Recoveries of pesticides wiped were variable, ranging from trace to near applied levels, and depended on surface type. Only a fraction of the pesticides were transferred to either press material when compared to wipes. This varied by pesticide and was highly dependent on duration of the press. On average, less than 50% of the pesticide were transferred from tile to C18 and PUF for the various times, except for 60% of the pesticides transferred from tile C18 after 60 minutes of pressing. For the average of all pesticides, C18 was slightly more efficient in the transfer of pesticides than PUF. In comparing the various times for both press materials, the average pesticide transferred to C18 was between 6 to 60% and for PUF was 2 to 50%. Transfer of pesticides from hard surfaces (tile and hardwood flooring) occurred more readily than from carpet. Negligible pesticides were transferred to either of the press materials from carpet.