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Wipe Sampling to Assess
Pesticide Exposures on Skin: Preliminary Method Evaluation
Mark F. Boeniger, National Institute for Occupational Safety and Health,
Cincinnati, OH, USA (Corresponding Author)
Marcia Nishioka, Battelle, Columbus, OH, USA
Tania Carreon, National Institute for Occupational Safety and Health,
Cincinnati, OH, USA
Wayne Sanderson, National Institute for Occupational Safety and Health,
Cincinnati, OH, USA
Background
Skin exposures to pesticides in agriculture are considered to be the primary
route of worker exposure. However, there remains a paucity of data for
quantifying such exposures. In addition, the methods used to measure exposures
vary and the efficiency of each method of sampling may differ, adding
to the difficulties in interpreting results. A preliminary range finding
and method evaluation survey was recently performed in California in preparation
for a larger study to determine exposure reduction intervention effectiveness.
Methods
Hand wipes (using the NHEXAS isopropanol moistened J&J Sof-Wick gauze
wipe method consisting of 2 consecutive wipes) were obtained during harvesting
of a strawberry field that had been previously sprayed with malathion.
To evaluate the performance of the hand wipe method, samples were collected
from whole hands and individual digits (thumb and forefinger) both before
and after cleaning up with soap & water. In addition, triplicate consecutive
samples were analyzed separately to assess completeness of malathion removal.
Additional types of samples were collected, included end-of-shift urine
for mono- and diacetyl metabolites, and foliar residue samples (using
a new method involving solid sorbent field extraction).
Results
Mean whole hand pre-wash and post wash malathion loading (n=5) was 8582
ng and 3493 ng while mean digit pre-wash and post wash malathion loading
(n=6) was 1457 ng and 965 ng, respectively. Furthermore, mean consecutive
removal of pre-washed digits (n=3 pair) were 1154, 558, and 436 ng, while
for whole hand (n=1 pair) 5550, 1340, and 1490 ng. After washing, mean
consecutive removal for digits was 557, 315, and 217 ng, respectively,
while for whole hand it was 1420, 1560, and 1130 ng. Wearing new latex
gloves during harvesting appeared to dramatically reduce skin loading,
while wearing old latex gloves did not.
Conclusions
The EPA hand wiping method apparently did not efficiently remove the amount
of malathion loading present either before or after washing, although
when loading was low (as when wearing gloves) removal appeared complete.
Perhaps alternative sampling methods are more efficient, but this would
need to be similarly evaluated. Efficiency of skin sampling methods and
comparison to other methods continues to be a significant need for accurate
exposure assessment characterization.
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