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HAND WIPE SUBSAMPLING METHOD FOR USE WITH BIOMARKER MEASUREMENTS IN THE AGRICULTURAL HEALTH STUDY/PESTICIDE EXPOSURE STUDY
Citation:
Clothier, J. M., D. E. Camann, K W. Thomas, AND S. M. Gordon. HAND WIPE SUBSAMPLING METHOD FOR USE WITH BIOMARKER MEASUREMENTS IN THE AGRICULTURAL HEALTH STUDY/PESTICIDE EXPOSURE STUDY. Presented at 11th Annual Meeting of the International Society of Exposure Analysis, Charleston, SC, November 4-8, 2001.
Impact/Purpose:
The primary goal of the AHS Pesticide Exposure Study (AHS/PES) is to measure exposure to applied pesticides for a subset of the cohort of private pesticide applicators and to provide data to evaluate exposure algorithms developed for exposure classification in the study cohort.
Description:
Dermal exposure studies incorporating urinary biomarker measurements are complicated because dermal sampling may intercept or remove the target chemical before it is absorbed. A hand wipe subsampling method has been developed using polyurethane foam-tipped (PUF) swabs to minimize the potential interference with urinary biomarker measurements. This paper describes tests to assess the method against an established method that measures whole hand residues by wiping with alcohol wetted gauze. Three neutral pesticides (chlorpyrifos, 2,4-D ethylhexyl ester and 2,4-D butoxyethyl ester) and one acidic herbicide (2,4-D) were tested in the laboratory, followed by field testing on seven pest control operators using both wipe procedures.
Twelve 1 x 3 cm2 rectangular areas were defined on the back and palm side of each hand using a commercially prepared rubber stamp inked with a red, water soluble 'tatoo' ink. Hands were allowed to dry approximately 15 minutes prior to permitting exposure-related activities. Hand surface areas were estimated using hand traces and digital imaging. When pesticide activities were completed, residues were wiped from within the inked areas on both hands using pre-cleaned isopropanol-wetted PUF swabs. The time required to apply twelve 1 cm x 3 cm ink outlines to each of two hands and then to collect the residues from within the outlined areas averaged 5 minutes. Wooden handles were clipped from swabs immediately after the wipe procedure and swab tips stored without solvent for analysis. The pesticides were removed from the swab tips by solvent extraction with acidified dichloromethane, reconcentrated, and analyzed on a GC/MS using selective ion monitoring.
PUF swab wipe efficiency was found to be equal to that of the whole hand wipe which has been shown to remove 80-100% of residues. Values generated using the digital hand trace indicated that 6-9% of the total hand surface was wiped with the swab. The extraction method achieved 75-125% recovery of the four pesticides in a single extraction. Estimates of residue loading from the subsampling method in field tests were higher than estimates from the whole hand method, but the correlation between the methods was 0.97. Based on measurements taken from two residential applications of chlorpyrifos using a hand-held sprayer, residues deposited on the palm area were higher than residues deposited on the back of the hand but lower than residues deposited on the thumb and forefinger. The hand wipe subsampling method is currently being used on pesticide applicators in the Agricultural Health Study/Pesticide Exposure Study.
This work was funded by the U.S. Environmental Protection Agency. It has been subjected to Agency review and approved for publication. Mention of trade names of commercial products does not constitute endorsement or recommendation for use.