THE DISTRIBUTION OF CHLORPYRIFOS IN AIR,
CARPETING, AND DUST AND ITS REEMISSION
FROM CARPETING FOLLOWING THE USE OF
TOTAL RELEASE AEROSOLS IN AN INDOOR AIR
QUALITY TEST HOUSE
Mark A. Mason1, Linda S. Sheldon2, Zhishi Guo3, and Daniel M. Stout II4.(1) U.S. EPA,
Office of Research and Development, National Risk Management Research Laboratory,
Indoor Environment Management Branch, Research Triangle Park, NC 27711, (919)
541-4835, mason.mark@epa.gov, (2) U.S. EPA, Office of Research and Development,
National Exposure Research Laboratory, Human Exposure Analysis Branch, Research
Triangle Park, NC 27711, (919) 541-2205, sheldon.linda@epa.gov, (3)U.S. EPA, Office
of Research and Development, National Risk Management Research Laboratory, Indoor
Environment Management Branch, Research Triangle Park, NC 27711, (919) 541-0185,
guo.zhishi@epa.gov, (4) U.S. EPA, Office of Research and Development, National
Exposure Research Laboratory, Human Exposure Analysis Branch, Research Triangle
Park, NC 27711, (919) 541-5767, stout.dan@epa.gov.
ABSTRACT
Experiments were conducted to explore the relationships between the insecticide
chlorpyrifos and its distribution into carpet, carpet dust, and reemission into air. Two total
release aerosols containing 0.5% chlorpyrifos were applied in the living room and den of
the EPA test house. Afterwards surface and carpet depositions, and carpet dust
concentrations were determined. Portions of the contaminated carpeting were removed
and placed in environmental chambers (0.053 m3). Emissions of chlorpyrifos from carpet
to air were determined. Air exchange rates and airborne chlorpyrifos concentrations were
measured in the test house over a 2-week period. Airborne chlorpyrifos concentrations in
the treated rooms of the test house exceeded 10 ug/m3 of air following 1 hour of
enhanced ventilation and declined to <1 ug/m3 by 14 days post-application.
Concentrations in the untreated bedroom were 11 times lower than in the den and living
room following ventilation, reached maximal levels by day 2, and declined to <0.5 ug/m3
by day!4. Surface loadings for dust were low compared to total surface deposition levels.
No vertical stratification was observed within rooms. Total levels quantified from the
carpet extraction and deposition coupons were similar in that levels were highest in
rooms that received applications and negligible in the master bedroom. Levels of
chlorpyrifos associated with house dust measured for all rooms increased immediately
following the application and remained above background through day 14. Source
emissions from carpet samples in chamber studies demonstrated that treated carpet is a
latent source for the reemission of chlopryrifos into air. However, carpet in an untreated
room did not appear to act as a sink for chlorpyrifos. Mass balance results for the
chamber and test house experiments indicate that factors other than the loss of the
pesticide via outdoor air exchange must be understood to account for the decrease of
pesticide in the treated carpet.
-------
INTRODUCTION
Pesticides are applied in and around human habitations to control a variety of pests and
may place toxicants in close proximity to humans and their activities. Pesticide residues
may translocate from their original points of application following treatment as vapors,
bound to particles, or through physical transport processes. The principal factors that
influence their movement are physiochemical properties (i. e., the vapor pressure of the
active ingredient and formulation type), the substrate that deposits are contacting, and the
physical activities of humans and pets. Pesticides that translocate indoors are less
influenced by the degrading factors such as photolysis and microbial activity that occur
out-of-doors. Furthermore, residues present indoors may persist or accumulate over time
and are commonly measured in residential dwellings at concentrations ranging from 10 to
100 times higher than those found out-of-doors'. Studies have shown that carpets and
associated carpet dust might serve as a latent source or reservoir of pesticide residues for
months to years following application 2>3. Contaminants adsorbed to surfaces or bound to
particles in "sinks" may disassociate as an airborne vapor or redistribute via particle
movement to become available for human exposures. Exposure to indoor pollutants such
as pesticides may pose risks to occupants through inhalation, dermal absorption, or
ingestion.
Pilot experiments were conducted in the U. S. EPA's indoor air quality research test
house in North Carolina to investigate the contribution of total release aerosols containing
the insecticide chlorpyrifos to airborne residue levels, and the distribution onto carpeted
surfaces, deposition coupons, and from carpet dust. In addition, carpet samples were
removed from two treated rooms and placed in ventilated 0.053m3 (53 L) environmental
chambers to determine reemissions of chlorpyrifos to air.
Indoor total release aerosols for chlorpyrifos were voluntarily withdrawn from the
consumer market subsequent to the conduct of this experiment. Recently, all indoor
consumer uses have been withdrawn. However, the data are relevant to understanding
the relationships between indoor applications of semivolatile pesticides, the movement of
like compounds in the indoor environment, and the potential for exposure.
MATERIALS AND METHODS
The study reported here was conducted in December 1993, in the U.S. EPA's Indoor Air
Quality Research Test House. The test house is an unoccupied one-story, seven-room •
(three bedroom), ranch-style house located in a residential neighborhood in Gary. NC
(Figure 1). The test house contains a total interior volume of 293 m3 with 122 m2 of
living area. All rooms are void of furniture and covered with wall-to-wall pile or shag
(den) nylon carpet except the kitchen and the bathrooms. The test house is
environmentally defined in that air exchange rates, temperature, and relative humidity are
continuously monitored.
Two commercially available canisters of an aqueous-based total release aerosol (Real
Kill, Realex Division of United Industries Corp., St. Louis, MO) formulated to contain
-------
0.5/o by weight of the insecticide chlorpyrifos [O,O-diethyl-O-(3,5,6-trichloro-2-
pyridinyl phosphorothioate] were purchased locally. Each canister was weighed before
and after the application to determine the total mass released. The canisters were
suspended 75 cm above the floor in the center of the den and living room wiA he spray
rps directed upward. Note that the rooms are open to the entry halLy^the kLhen
(Figure 1 and their physical separation is only partial. Prior to activation of tie aerosol
device, all windows and mterior doors were closed, the furnace pilot light was
extinguished and the furnace fan was turned off. Upon activation, the housTwas vacated
and reentered 2 hours later when the exterior doors and windows in the livingToom and
den were opened and allowed to ventilate for 1 hour. Afterwards, the windows an™
exterior doors were closed, the furnace pilot was re-ignited, and the ceiling fans in the
0e™JyV"?g roomwere turned on at low speed. The house thermostat was set to 72 °F
(22 C) for the duration of the experiment. The interior doors were closed throughout the
test except for ingress and egress by the research scientists to and from the mastfr
bedroom in order to perform sampling activities.
Prior to the insecticide treatment, three or four round plugs (0.0005 m2, 25 4 mm dia)
were precut m the carpet with a filter punch at selected locations. The carpet plugs were
cut from the center of the living room, den, and master bedroom, from rrSway between
the baseboards and the center and from within 0.05 m of the base boards as shown in
Figure 1. A single precut carpet plug was removed from each carpet sampling location in
Sr^^^^^^,4161^^ ba,ck^ound chlorpyrifos levels in The
e remamina rarn^t nlnrro „„,,.„ l^A ,„ I,... ^-. ,, .. t j^^
Figure 1. Sampling locations in EPA's test house.
Master
bedroom
9
Clos iCIos
~ ^ Clos """]j_
Corner
bedroom
Bath
Clos
Den
9 •
o
o
°0
*
OOOOI
Return I—
air
Clos
Utility
Middle
bedroom
Precut 1in. carpet plugsoooo (NOTTOSCALEJ
Deposition sample I
Carpet dust collection site £3
Kitchen
LR
Clos
o*
ooooi
Small chamber carpet sample CD
Polyurethane foam air sampler O
Release Site ^ *
Test
instruments
Garage
-------
Deposition coupons consisting of 1 in. square foil-backed gauze pads were affixed with
safety pins to the floor adjacent to the carpet plugs. A carpet plug and a deposition
coupon were removed from each carpet sampling location immediately following the
ventilation period. The remaining carpet plugs were removed at the end of the 2-week
test period. Both sample types were collected using clean solvent-rinsed forceps, placed
in labeled glass jars, and stored in ice chests at reduced temperatures for transport.
For subsequent chamber testing, 0.09 m2 (30.5 X 30.5 cm) sections of carpet were precut
1 -m from a corner m the den and living room. The carpet sections remained in place and
were collected from the treated rooms upon entry following the air-out procedure Upon
collection the carpet sections were sealed in Tedlar® bags, transported to the laboratory
immediately removed from the Tedlar® bags, and placed in the EPA's electropolished
stainless steel, 0.053 m3 (53-L) test chambers. The chambers were held at a temperature
of 23 °C and supplied with purified air that was conditioned to a relative humidity of
45%. Chamber airflow was maintained at a constant rate of 0.4 L/min, providing an
exchange rate of approximately 0.45 h'1. Each carpet section was placed fiber side up at
the bottom of each chamber. A small biscuit fan mounted in the center of each chamber
and 7.4 cm from the sample maintained a nominal air speed of 5 to 10 cm/sec above the
surface of each carpet section. Airborne chlorpyrifos concentrations in the chamber were
collected using polyurethane foam (PUF) filters held in glass housings and vacuum
pumps calibrated to a constant flow rate of 200 cm3/min. Sampling intervals varied in
duration from 2 to 24 hours to provide appropriate loading on the PUF sorbents.
Vacuum-dislodged dust was collected using the high-volume sampler (HVS3) using
ASTM D5438-93 in the master bedroom, living room, and den. Each location consisted
of an area of 1.5 m (1 by 1.5 m) outlined with masking tape in the center of each of four
designated quadrants in each room. Vacuum sweepings were collected from a single
quadrant in each room just prior to the treatment, immediately following the period of
enhanced ventilation and at 2 weeks post-application.
Air was monitored using PUF filters held in glass filter housings. Monitoring was
conducted in the living room and den at 25, 100, and 200 cm above the floor immediately
following the application and at the end of the 2-week sampling period, while all
subsequent samples were collected at 100 cm above the floor. Measurements were
collected for 1 hour using pumps calibrated to a continuous flow rate of 15 L/min.
Following the sample collection, the PUF filters and housings were wrapped in clean
aluminum foil, individually sealed in plastic bags, and stored in ice chests at reduced
temperatures for transport.
The indoor/outdoor air exchange rates were monitored throughout the study using a tracer
gas technique5. Sulfur hexafluoride (SF6) was released every 2 hours at the furnace-
return's air-vent and monitored once every 5 minutes in the master bedroom, den, and
living room. The concentration of SF6 was determined by gas chromatography with
electron capture detection (HP 5890, Poropac Q, 6mm X 2 m column). To determine the
air exchange rate during the flush-out period, SF6 was released just prior to opening
exterior doors and windows. The furnace fan was activated to mix the SF6 throughout the
-------
house. During the air-out procedure, concentrations of SF6 were monitored only in the
den to obtain a sufficient number of measurements.
The PUF filter and carpet plugs were Soxhlet extracted in 5% ethyl ether/ hexane and
concentrated to a final volume of 10 mL for analysis. Vacuum sweepings were separated
with a #10 sieve to obtain a fraction smaller thanlSO urn. A 0.5 g aliquot of the sieved
fraction was Soxhlet extracted in 5% ethyl ether/ hexane and concentrated to a final
volume of 10 mL for analysis. The surrogate standard, tetrachloronaphthalene, was added
to each sample prior to extraction to assess overall method performance. After the final
concentration step, pentachloronitrobenzene was added to the sample extracts as an
external quantitation standard. Samples were analyzed using a Varian 3700 gas
chromatograph equipped with a liquid autosampler and electron capture detector A DB-5
fused silica column (30 m X 0.32 mm) was used for quantitation. The carrier flow rate
was 2.0 mL/mm. The temperature program was initiated at 80°C and ramped to 300°C at
4 C /mm. The capillary injector was operated in the splitless mode for 1 min. Injector and
detector temperatures were 280 and 320 °C, respectively.
Label instructions for the pesticide state that each canister must be released in an area
with a volume of at least 1500 ft3. With interior doors closed, the den, kitchen living
room, dining room, entry hall, and main hall leading to the bedrooms form a contiguous
space with 55 m of floor area with a volume of 158 m3 or 5600 ft3. Based upon the
labeled percent active ingredient and the net weight of the containers, a total of 1700 me
of chlorpynfos would be released. If the pesticide all deposited evenly on the contiguous
floors, then predicted loading would be 31 mg/m2.
Quality Control
Quality control included reagent and field blanks, reagent, PUF sampler, and carpet
spikes as well as duplicate samples and replicate analyses. Chlorpyrifos was not detected
(<50 ng/sample) in the nine reagent blanks or three PUF field blanks. Nine reagent blanks
and three field control PUF cartridges were each fortified with 500 ng of chlorpyrifos and
provided recovery efficiencies (mean ± standard deviation) of 93 ± 6%, and 90 ± 2%,
respectively. Three carpet plugs were each fortified with 51 ug of chlorpyrifos and gave
recoveries of 83 ± 11%. Three aliquots of carpet dust fortified with 10 jag of chlorpyrifos
gave recoveries of 106 ± 4%. The surrogate standard (tetrachloronaphthalene) was added
to all 149 samples of the study and provided a recovery efficiency of 100 ± 12%.
RESULTS AND DISCUSSION
The chlorpyrifos loadings measured from deposition coupons in the living room and den
ranged from 28 to 73 mg/m2 (Table 1). Residues for all rooms were highest nearest the
spray canister (the center of the room) and decreased by approximately half at the
midpoint and baseboards. Loadings measured from the master bedroom ranged from non-
detectable (O.08 mg/m2) to 0.44 mg/m2. Average levels measured from the master
bedroom were 2 orders of magnitude lower than those measured in the two treated rooms.
-------
Center
Midpoint
Baseboard
—
Baseboard 2
1 Center
Midpoint
Baseboard 1
Baseboard 2
Mean ±S.D.
73(120)
28
29
32
47±34
30±2.1C
44 (55)
21
30
20
30±14
24±5.5C
Center
Midpoint
Baseboard 1
Baseboard 2
Mean ±S.D.
—
—
—
--
—
30
14
17
19±7.6
15±1.7C
0.060
14 Days Post-Application
49
18
9A
9
3
t
\
18
.3°
-
0.87(0.83
—
-
~
0.68
0.93"
0.69
0.77±0.14
" No sample
b Results for duplicate sample
c Calculated without center sample
A mean surface loading of 44 mg/m2 for the 55-m2 contiguous floor was determined from
the four sampling locations in the treated rooms. A total estimated deposition of-2420
mg for the treated rooms is -720 mg greater than the theoretical total mass of 1700 mg
emitted from the total release aerosols as determined from the label concentrations The
mean of the two deposition samples from the center of the treated rooms was 75 mg/m2
compared to a mean of 31 mg/m2 for all other locations. Clearly, the application resulted
in a non-homogeneous distribution of chlorpyrifos on the carpet. High surface loading
0.0013
-------
immediately adjacent to the canister likely biased the mean values and overestimated the
loading.
The theoretical distribution of chlorpyrifos on the treated carpeting based on the label
concentration is 31 mg/m2. The net weight loss from the canisters was in close
agreement with the label amount. On the other hand, the concentration of chlorpyrifos in
the canisters was not confirmed by independent measurement.
The aqueous-based total release aerosols produced a mist of particles in the air of the
treated rooms. The deposition and carpet extract data indicate that the bulk of the active
ingredients were deposited on the carpets of the contiguous rooms during the 2 hours
following the release. Minimal deposition onto surfaces in the master bedroom suggests
that the combination of closed doors and the heating and air-conditioning system in the
off state likely minimized contamination in the untreated room.
Background levels of chlorpyrifos were detected from the total carpet extracts in all
rooms (Table 1). Mean background levels were less than 1 mg/m2 in all rooms and
approximately 5 times greater in the pile carpets of the master bedroom and living room
compared to the den. The average carpet loading for the living room and den increased
above background to 30 and 48 mg/m2, respectively, following the application and
declined by approximately half by day 14. These loadings are similar to those measured
with the deposition coupons. Concentrations measured from carpet in the untreated
master bedroom show little variation throughout the test period. The carpets were not
sampled for 3,5,6-trichloro-2-pyridinol, a primary metabolite of chlorpyrifos.
Low background levels of chlorpyrifos were measured from house dust collected prior to
the application (Table 2). The concentrations of chlorpyrifos extracted from the pre-
application dust samples were similar from room to room (0.00019, 0.00015, and
0.00023 mg/g for the living room, den, and master bedroom, respectively). On an area
basis, the higher amounts seen at preapplication in the den are due to a greater amount of
extractable dust in the shag carpet. Chlorpyrifos concentrations from carpet dust
increased above background following the application in the den and living room and
remained above background levels through day 14. Similarly, chlorpyrifos loadings in
dust of the untreated master bedroom increased immediately following the application
and remained above background. Prior to the application, 0.01 and 0.41% of the pesticide
extracted from the carpets was found in the dust samples of the living room and den,
respectively (calculated by dust loading/ average carpet loading from each room).
Following the application, about 2% of the total extractable chlorpyrifos was associated
with the dust fraction from these rooms. This suggests that very little of the pesticide is
bound to dust particles; rather, it is in the residue form in contact with carpet material.
The dust collected by the HVS3 may have been tainted from residues on the freshly
treated carpet. Therefore, the dust concentrations measured following the application
should be considered as upper limit estimates.
-------
Table 2. Chlorpyrifos extracted from carpet dust fractions collected at intervals following
a pesticide application using total release aerosols.
Day
Preapplication
Application
Post Day 14
Living
Loading
(mg/m )
0.00012
0.52
0.060
Room
Concentration
(mg/g)
0.00019
0.68
0.080
Den
Loading
(mg/m )
0.00055
1.0(0.95)
0.87 (0.83)
Concentration
(mg/g)
0.00015
0.11(0.10)
0.26 (0.25)
Master Bedroom
Loading
(mg/m )
0.00013
0.0024
0.0013
Concentration
(mg/g)
0.00023
0.0031
0.0039
Prior to the aerosol application, airborne levels of chlorpyrifos were below detectable
levels (O.05 ug/m3) (Table 3). Only slight differences between airborne concentrations
were observed between 25 and 200 cm above the floor in the living room and den at post
application day 14, when samples were collected at three elevations. Residues measured
at 100 cm above the floor in the two treated rooms both reached highest levels of about
16 ug/m3 immediately following the application and decreased to about 0.4 ug/m3 by
day!4. These findings agree with those of other studies6 where, following the use of total
release aerosols containing chlorpyrifos, airborne concentrations ranged between 3 and
50 ug/m3. Conversely, airborne concentrations measured in the untreated master bedroom
were determined to be 1.4 ug/m3 immediately following the application and 4.7 ug/m3 24
hours later. The apparent delay in peak concentration in the untreated room is surprising
since the air handling system mixes SFe evenly throughout the house within 15 min of
release at the return air grill. However, sampling frequency may not have been adequate
to identify peak concentrations and characterize the time concentration profiles in the
treated and untreated rooms. The air concentrations declined to < 0.5 ug/m3 in the treated
rooms and the master bedroom by day 14.
Table 3. Chlorpyrifos concentrations measured from the indoor air of the IAQ test house
following a pesticide application using total release aerosol.
Day
Preapplication
Application
Application
Application
Post Day 1
Post Day 2
Post Day 3
Post Day 7
Post Day 14
Post Day 14
Post Day 14
Sampling Height
(cm)
100
25
100
200
100
100
100
100
25
100
200 .
Living Room
(ug/m3)
NDa
16
15(15)c
16
9.2
4.1
2.3
0.86
0.49
0.45
0.48
Den
(ug/m3)
ND
18
17
16
8.3 (7.5)
4.0 (3.3)
2.1
1.1
0.5
0.41 (0.43)
0.38
Master Bedroom
(ug/m3)
NCb
NC
1.4
NC
4.7
NC
NC
0.37 (0.37)
NC
0.32
NC
aNot detected (O.05 ug/m3).
b Not collected.
c Result of duplicate sample analysis.
-------
The outdoor air exchange rate for the den and dining room was determined to be 4.3 h"1
during the ventilation period while the exterior doors and windows were fully open. For
the remainder of the test, with windows and interior doors closed, the air exchange rates
for the living room, den, and master bedroom averaged 0.75 h"1. The ventilation during
the 1-hour air-out procedure is sufficient to exhaust >99% of the air in the den and living
room at the end of the 2-hour period following the release. Thus, the air concentration in
the first air sample, which accounts for less than 0.2% of the amount released, is due to
reemission of chlorpyrifos from treated surfaces or resuspension of dust or droplets. The
amount of chlorpyrifos leaving the house via the air during the 2-week experiment,
estimated from the sum of the integrated time/concentration data (mg/m3) multiplied by
air exchange rate (1/h), and volume (m3), is 100 to 130 mg. This accounts for about 10%
of the net decrease of chlorpyrifos observed for the carpets over the same period,
suggesting translocation of residues to other surfaces that were not sampled and/or
breakdown of the parent compound.
Following the placement of carpet sections in the 53-L test chambers, the airborne
chlorpyrifos concentrations increased to their highest levels by 6 h, followed by a gradual
decline to ~1 ug/m3 by 492 h. Carpet loads for test chamber samples were estimated at 24
± 6 and 34 ± 12 mg/m2 based on the average of the baseboard and midpoint carpet
samples from the living room and den, respectively. The total extractable chlorpyrifos
concentrations of 5.0 and 2.3 mg/m2 were determined from total extracts of the carpets
following 492 h in the test chambers. The mass of chlorpyrifos exiting each chamber was
determined from the product of the integrated time/concentration (|o,g/m3) plot times
chamber flow (m3/h) and elapsed time (h). This provided a calculated mass of 44 and 52
ug for the living room and den carpets, respectively, which accounts for only 2 to 3% of
the chlorpyrifos loss from the carpets and suggests significant adsorption by chamber
surfaces.
Figure 2. Chlorpyrifos concentrations in small environmental chambers.
O
0
e-
O 10
!E
O „
o*
100 150 200 250 300 350 400 450
Elapsed time (h)
* Living Room (pile carpet) • Den (shag carpet)
-------
CONCLUSIONS
The aqueous-based total release aerosol produced a heterogeneous distribution of
chlorpyrifos in the treated rooms. The data indicate that most of the particles released
from the canister deposit on floor surfaces within 2 hours of release,-consistent with
settling rates for particles > 20 urn7. However, the findings demonstrate that the
application devices also produced an area of undefined size with chlorpyrifos loadings
over 2 times higher than the rest of the room. This factor may be important when
considering potential human exposures to deposits of semivolatile pesticides following
this type of treatment. Findings show that most chlorpyrifos deposited on carpeting in the
treated rooms while little intruded into the non-target master bedroom area. Furthermore,
it appears that closing doors and turning off the heating and air-conditioning system prior
to the aerosol release may have reduced the movement of chlorpyrifos from the treated
rooms to other rooms immediately following the application. Airborne concentrations of
a semivolatile insecticide may increase for several hours after application due to
reemission from treated surfaces. Clearly, and consistent with earlier observations of
Leidy et al.8, chlorpyrifos, a semivolatile insecticide, volatilizes at measurable levels
following indoor applications. The chamber studies show that chlorpyrifos continues to
volatilize from the treated carpeting 3 weeks after the application. The apparent delayed
increase of airborne concentrations by 24 hours in the master bedroom suggests a
distribution pathway associated with passive diffusive processes or by active transport
(principally the air-conditioning system). The balance of the total mass of chlorpyrifos
delivered into the test house remains incomplete. A 50% decrease of chlorpyrifos from
the treated carpet by 2 weeks post-application cannot be accounted for by the
chlorpyrifos vapors collected or through whole-house air exchanges. Speculatively, the
unaccounted for mass moved as a vapor and sorbed to household substrates (walls,
ceilings, etc.) that were not measured in this study. This pilot study did not characterize
adsorption/desorption to environmental surfaces, or decay rates of chlorpyrifos in indoor
environmental conditions. There was no net increase observed for the total extractable
chlorpyrifos in the carpet of the untreated bedroom. Thus, the carpeting in the untreated
room does not appear to be a strong sink for vapor-phase chlorpyrifos over the 2-week
sampling period.
Acknowledgements
Sampling at the test house and all analytical tasks were conducted by Research Triangle
Institute under EPA cooperative agreement CR817083.
REFERENCES
1. Lewis, R.G. and MacLeod, K.E., Portable Sampler for Pesticides and Semivolatile
Industrial Organic Chemicals. Anal. Chem. 54, 310-315 (1982).
2. Immerman, F. W. and Shaum, J. L., Nonoccupational Pesticide Exposure Study
(NOPES), EPA-600/3-90/003, (NTIS PB90-152224), U.S. Environmental Protection
Agency, Atmospheric Research and Exposure Assessment Laboratory, Research Triangle
Park, NC (1990).
10
-------
3. Lewis, R.G., Fortmann, R.C., and Camann, D.E., Evaluation of Methods for
Monitoring the Potential Exposure of Small Children to Pesticides in the Residential
Environment, Arch. Environ. Contam. Toxicol. 26, 37-46 (1994).
4. ASTM. Standard Practices for Collection of Dust from Carpeted Floors for Chemical
Analysis D5438-93. In Annual Book of ASTM Standards, Vol. 11.03; American Society
for Testing Materials; Philadelphia, PA, 1994.
5. ASHRAE, ASHRAE Handbook of Fundamentals, American Society of Heating,
Refrigeration and Air-Conditioning Engineers, Inc., Atlanta, GA, 1985; p 228.
6. Vaccoro, J. R., Risks Associated with Exposure to Chlorpyrifos and Chlorpyrifos
Formulation Components. In Pesticides in Urban Environments; Racke, K. D., Leslie, A.
R., Eds.; American Chemical Society: Washington, DC, 1992: pp. 297-306.
7. Baron, P., Aerosol Calculations Software. 43 Arcadia Place, Cincinnati, OH.
Copyright 1987 - 1996. Version Date September 5, 1996.
8. Leidy, R. B., Wright C. G., and Dupree, H.E. Jr. Exposure Levels to Indoor Pesticides.
In Pesticides in Urban Environments; Racke, K. D., Leslie, A. R., Eds.; American
Chemical Society: Washington, DC, 1992: pp. 282-296.
Key Words
Pesticide
Chlorpyrifos
Carpet
House dust
Distribution
Reemission
11
-------
NRMRL-RTP-P-533
TECHNICAL REPORT DATA
(f lease read Instructions on the reverse before completing^
1. REPORT NO.
EPA/600/A-00/-60
2.
3. RE
<• TITLE AND SUBTITLE The Distribution of Chlorpyrifos in
Air, Carpeting, And Dust and its Reemission from
Carpeting Following the Use of Total Release Aerosols it
anIndoor Air Quality Test House
5, REPORT DATE
6. PERFORMING ORGANIZATION CODE
7-AUTHOR(s)M. Mason (NRMRL), L.Sheldon (NERL).
Z.Guo (NRMRL), and D. Stout (NERL)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORQANIZATiON NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
U.S. EPA
National Exposure Research Laboratory
Human Exposure and Analysis Branch
Research Triangle Park, North Carolina 27711
11. CONTRACT/GRANT NO.
CR817083 (Research
Triangle Institute)
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Air Pollution Prevention and Control Division
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Published paper; 10/93-6/94
14. SPONSORING AGENCY CODE
EPA/600/13
is.SUPPLEMENTARY NOTES
project officer is Mark A. Mason, Mail Drop 54, 919/541-
4835. For presentation at Engineering Solutions to IAQ Problems, Raleigh, NC,
7/17-19/00.
IB. ABSTRACT
paper gives results of experiments to explore the relationships between
the insecticide chlorpjrifos and its distribution into carpet, carpet dust, and reemis1
sion into air. Two total release aerosols containing 0.5% chlorpyrifos were applied
in the living room and den of EPA's test house in North Carolina. Afterwards, sur-
face and carpet depositions, and carpet dust concentrations were determined. Por-
tions of the contaminated carpet were removed and placed in environmental cham-
bers (0.053 cu m). Emissions of chlorpyrifos from carpet to air were determined.
Air exchange rates and airborne chlorpyrifos concentrations were measured in the
test house over a 2-week period. Airborne chlorpyrifos concentrations in the treated
rooms of the test house exceeded 10 micrograms/eu m of air following 1 hour of en-
hanced ventilation and declined to <1 microgram/cu m by post- application day 14.
Concentrations in the untreated bedroom were 11 times lower than in the den and liv-
ing room following the ventilation, reached maximum levels by day -2, and declined
<0.5 microgram/cu m by day 14. Surface loadings for dust were low compared to
total surface deposition levels. No vertical stratification was observed" within rooms
Total levels quantified from the carpet extraction, and deposition coupons were simi-
lar.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Pollution
Carpets
Dust
Aerosols
Insecticides
Ventilation
Pollution Control
Stationary Sources
Chlorpyrifos
Indoor Air
13B
HE
11G
07D
06F
ISA
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS {ThisReport)
Unclassified
21. NO. OF PAGES
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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