United States
Environmental Protection
Agency
National Exposure
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-96/089 August 1996
EPA Project Summary
Comparison of Methods to
Determine Dislodgeable Residue
Transfer from Floors
David E. Camann, H. Jac Harding, Paul W. Geno, and Susan R. Agrawal
Comparisons were made of the trans-
fer of formulated pesticide residues
from treated carpets and vinyl flooring
by three dislodgeable residue methods
and by human skin. The Dow drag sled
and the Southwest Research Institute
polyurethane foam (PDF) roller per-
formed better than the California cloth
roller. Moistening the sampling media
increased the transfer by the drag sled
and the PDF roller, but substantially
increased measurement variability. An
isopropanol handwipe method effi-
ciently removed dried pesticide resi-
dues from the hands of volunteers
(104% of chlorpyrifos, 92% of pyrethrin
I). The transfer efficiency of the drag
sled consistently exceeded the trans-
fer efficiency of the PDF roller, which
consistently exceeded the transfer effi-
ciency of human hand presses. This
relationship was observed for a variety
of pesticides, loadings, application
methods, and surfaces.
Both the drag sled and the PUF roller
were found to be acceptable dislodgeable
residue methods on the basis of these
studies. The pliable polyurethane foam
sampling surface of the PUF roller with
its rolling action is likely to better simu-
late human skin in its pesticide trans-
fer via contact with surfaces than is
the denim cloth of the Dow sled with
its drag action. Either mechanical
method can be used to estimate der-
mal transfer of pesticide residues from
recently treated floors. Round-robin
testing of the drag sled and PUF roller
by potential registrants is recom-
mended under strict QA/QC guidance
from the U.S. Environmental Protection
Agency (EPA). This report was submit-
ted on Contract 68-DO-0007 by South-
west Research Institute under subcon-
tract to Battelle under the sponsorship
of the U.S. EPA. Work was conducted
from July 1992 to September 1993 and
the report was completed as of No-
vember 1995.
This Project Summary was developed
by the National Exposure Research
Laboratory's Air Measurements Re-
search Division, Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
After a pesticide application in a home,
the residents may receive dermal expo-
sure through direct contact with the treated
surfaces. The exposure of young children
after treatment of carpets and baseboards,
both through direct skin contact and
through mouthing of hands and objects, is
a particular concern. The Dow drag sled,
California cloth roller, and PUF roller are
dislodgeable sampling methods which
have recently been developed to estimate
the transfer of a chemical from a contami-
nated surface to the skin. The objectives
of this study were to compare the transfer
rates of pesticides from treated flooring
among these three methods and against
transfer to a human hand; to determine
the wipe removal efficiency of pesticides
from hands by an isopropanol handwipe
method; and to evaluate the effects of
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carpet type, moistened sampling media,
other sampling variables, and tempera-
ture on mechanical transfer.
Procedure
For the drag sled method, one pass
was made over a 1-m strip of flooring by
dragging a precleaned denim-weave cloth
attached beneath foil under a (3 in)2 ply-
wood block on which an 8-lb weight was
mounted to provide a contact pressure of
5900 Pa through the cloth. The California
cloth roller method consisted of placing a
precleaned (17 in)2 percale cloth covered
with plastic sheeting on the floor and mak-
ing 20 rolling passes over it with a PUF-
wrapped, capped 2 ft. x 4 in. diameter
plastic pipe containing 25 Ibs of shot, to
provide a contact pressure of 2300 Pa
through the cloth. For the PUF roller
method, one pass was made over a 1-m
strip of flooring by rolling a precleaned 3
in-long ring of PUF mounted on an alumi-
num cylinder, with two stainless steel
blocks mounted on the instrument frame
to provide a constant contact pressure of
8000 Pa through the PUF ring. For the
hand press method, a subject made one
pass over a cardstock-template-exposed
0.64 m x 3 in strip of flooring by pressing
the soap-and-water-washed palm of one
hand for 1 s at a pressure of about 1 psi
(6900 Pa) onto each often adjoining sec-
tions of the strip. The subject wiped trans-
ferred residues from his hand using two
isopropanol-moistened gauze sponges.
A series of experiments was performed
to compare the transfer from carpet or
vinyl flooring of recently-applied formula-
tions of chlorpyrifos, natural pyrethrins, and
piperonyl butoxide by these methods. A
licensed pest control applicator treated the
test flooring for each experiment accord-
ing to label directions to control flea infes-
tation. Adjacent deposition coupon and
transfer samples for the compared meth-
ods were sequentially collected for each
experiment, usually within each of six rect-
angular blocks of treated flooring. Field
blanks of each transfer method were ob-
tained by sampling prior to the applica-
tion. Field samples were collected from at
least two blocks after label-permitted re-
entry (>2 hr after application) on the day
of application, and also on the next two
days if human subjects performed hand
presses. Field spikes of each precleaned
transfer medium were performed both be-
fore and after the field sampling to assess
losses during transport, storage, and ex-
traction.
Results and Discussion
Mean transfer of chlorpyrifos from
treated carpet onto the dry sampling me-
dia of the mechanical methods, when used
as described by their developers, was larg-
est for the California cloth roller, interme-
diate for the drag sled, and smallest for
the PUF roller. This relation was observed
for both plush nylon and level-loop polypro-
pylene carpet. The California cloth roller
was found to be less practical and more
variable than the drag sled or PUF roller
methods.
Transfers of chlorpyrifos from plush car-
pet onto water-moistened sampling media
were larger than transfers onto dry media,
for both the PUF roller and the drag sled.
However, transfers onto water-moistened
media were substantially more variable.
Transfer sampling with water-moistened
media was found to be impractical.
Both the drag sled and the PUF roller
transferred an amount of formulated
chlorpyrifos residue from plush carpet
which was generally proportional to the
length of carpet traversed. An essentially
constant amount of chlorpyrifos appeared
to transfer to the PUF roller on each of
the first 20 passes over a 1-m strip of
treated plush carpet.
Increasing the pressure applied by the
drag sled to chlorpyrifos-treated plush car-
pet had little effect on chlorpyrifos transfer
to the cloth sampling medium. In contrast,
increasing the pressure applied through
the PUF ring by the roller sampler pro-
duced a nearly proportional increase in
chlorpyrifos transfer. As the carpet tem-
perature increased, the drag sled and PUF
roller both transferred slightly larger
amounts of both fresh and aged residues
of several pesticides from plush carpet.
The isopropanol hand wipe method effi-
ciently removed dry pesticide residues from
the hands of two volunteer subjects within
the first minute after their transfer from
aluminum fog to the hand. Wipe removal
efficiency was determined by mass bal-
ance after accounting for extraction and
elution efficiency. The mean wipe removal
efficiencies from hands were 104 % (s =
11%, n = 12) for formulated chlorpyrifos,
and 92% (s = 28%, n =12) for formulated
pyrethrin I fortified with analytical stan-
dard.
The transfer efficiency of formulated pes-
ticide residues from treated carpets and
vinyl flooring was consistently highest for
the drag sled, intermediate for the PUF
roller, and lowest for human skin. In com-
paring transfers of formulated chlorpyrifos,
pyrethrinl, piperonyl butoxide, and
methoprene, the specific active ingredient
had virtually no effect on transfer efficiency.
However, transfers by each method were
about an order of magnitude higher from
sheet vinyl than from carpet. Greater trans-
fers from carpet were observed for an
aerosol can formulation than for a broad-
cast formulation.
The observed mean standard deviation
of the multiplier of hand press transfers
obtained by the mechanical methods was
7.4 +/- 2.8 for the drag sled and 3.3 +/-
2.1 for the PUF roller (n = 17). Either
mechanical method can be used to esti-
mate dermal transfer of pesticide residues
from recently treated floors.
Conclusions and
Recommendations
Both the drag sled and the PUF roller
were found to be acceptable dislodgeable
residue methods on the basis of this study.
Dermal transfer of pesticide residues can
be estimated from transfers by the drag
sled or PUF roller. Ratios which appear to
apply to measurements on recently treated
floors were obtained in this study. Round-
robin testing of the drag sled and PUF
roller is recommended under strict QA/QC
guidance from EPA.
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David E. Camann, H. Jac Harding, Paul I/I/ Geno, and Susan R. Agrawal are with
Southwest Research Institute, San Antonio, TX 78228-0510.
Robert G. Lewis is the EPA Project Officer (see below).
The complete report, entitled "Comparison of Methods to Determine Dislodgeable
Residue Transfer from Floors," (Order No. PB96-196712; Cost: $28.00, subject
to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air Measurements Research Division
National Exposure Research Laboratory
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection Agency
National Risk Management Research Laboratory (G-72)
Cincinnati, OH 45268
Official Business
Penalty for Private Use $300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-96/089
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