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.

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 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-doors1. 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 application2'3. 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 semi volatile 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 m with 122 rn  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

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0,5% by weight of the insecticide chlorpyrifos [O,O-diethyl-O-(3,5,6-triehloro-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 with the spray
tips directed upward. Note that the rooms are open to the entry hallway and the kitchen
(Figure 1) and their physical separation is only partial. Prior to activation of the aerosol
device, all windows and interior doors were closed, the furnace pilot light was
extinguished, and the furnace fan was turned off. Upon activation, the house was vacated
and reentered 2 hours later when the exterior doors and windows in the living room and
den were opened  and allowed to ventilate for 1 hour. Afterwards, the windows and
exterior doors were closed, the furnace pilot was re-ignited, and the ceiling fans in the
den and living room were 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 master
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  in 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 midway 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
each room prior to the treatment to determine the background chlorpyrifos levels in the
carpeting. The remaining carpet plugs were left in place for collection at later sampling
intervals. See Figure 1.
Figure 1. Sampling locations in EPA's test house.
  Master
  bedroom
                           Master
                           bath
                          Bath
  Clos  I CIos
     Clos    ]
     Corner
     bedroom
Return   ~'~
  air  "
                                          Den
                              9
                                                    v^yo
                                                    oo
               °0
                *
Kitchen
                                                     9
                                            LR
     Middle
     bedroom
                                               ClOS
                                                           m
                                                                           Test
                                                                         instruments
                             Garage
Precut 1 in. carpet plugsoooo  (NOTTOSCALEJ    Small chamber carpet sample CD
Deposition sample  •                  Polyurethane foam air sampler Q
Carpet dust collection site £3             Release Site  ®>

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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 in 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 D5438-934 in the master bedroom, living room, and den. Each location consisted
of an area of 1.5 m2 (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 SFe 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 than 150 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/min, The temperature program was initiated at 80°C and ramped to 300°C at
4°C /min. 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 m2 of floor area with a volume of 158 m3 or 5600 ft . Based upon the
labeled percent active ingredient and the net weight of the containers, a total of 1700 mg
of chlorpyrifos would be released. If the pesticide all deposited evenly on the contiguous
floors, then predicted loading would be 31 mg/m .

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 u.g of chlorpyrifos and gave
recoveries of 83 ± 11%. Three aliquots of carpet dust fortified with 10 p,g 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 (<0.08 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.

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Table 1, Chlopyrifos loadings measured from deposition coupons, carpet samples, and
housedust.
Location
Loading (mg/m2)
Living Room
deposition carpet
dust
Den
deposition carpet
dust
Master Bedroom
deposition
carpet
dust
Preapplication
Center
Midpoint
Baseboard 1
Baseboard 2
Mean ±S,D.
--a
~
—
--
--
0.71
1,1
0.78
0.71
0.83 ±0.1 9
—
0.00012
—
—
--
--
—
—
—
--
0.12
0.12
0.20
0.10
0.14±0.04
--
0.00055
—
—
—
—
—
—
—
--
0.8I(0.75)b
0.78
0.73
0.61
0,62±0.23
—
0.00013
—
--
—
Application Day
Center
Midpoint
Baseboard 1
Baseboard 2
Mean ±S.D.
73(120)
28
29
32
47±34
30±2.1C
44 (55)
21
30
20
30il4
24±5.5C
--
0.52
—
--
—
72 (74)
37
29
31
43±21
32±4.2C
96(83)
33
22
46
48±30
34±12C
—
1.0(0.95)
—
—
—
0.44
0.23
<0.08
0.39
0.28±0.18
0.69
0.91
1.10
0.59
0.83±0.22
—
0.0024
~
—
—
14 Days Post- Application
Center
Midpoint
Baseboard 1
Baseboard 2
Mean ±S.D.
--
--
—
--
—
30
14
14
17
19±7.6
15±1.7C
—
0.060
—
—
—
—
—
—
—
—
49
18
14
9.4
22±18
14±4.3C
—
0,87(0.83)
—
—

™-
*"
"""
—
"*"
—
0.68
0.93
0.69
0.77±0.14
—
0.0013
"""
~
"
a 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/m
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

-------
 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/m .  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.

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 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.

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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)

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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

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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

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 NRMRL- RTF- P- 533
       TECHNICAL REPORT DATA
(Please read Iruouctions on the reverse before completing,
1. REPORT NO.
      EPA/600/A-00/-60
                           2.
                                                      3. RE
4. TITLE AND SUBTITLE
                The Distribution of Chlorpyrifos In
Air, Carpeting, And Dust  and its Reemission from
Carpeting Following the Use of Total Release Aerosols  in
anIndoor Air Quality Test
                                                      5. REPORT DATE
                             6. PERFORMING ORGANIZATION CODE
7-*UTHOR(s>M. Mason (NRMRL),  L.Sheldon  (NERL),
 Z.Guo (NRMRL), and D. Stout (NERL)
                                                      8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION 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 277U
                                                       13. TYPE OF REPORT AND PERIOD COVERED
                                                       Published paper; 10/93-6/94
                             14. SPONSORING AGENCY CODE
                               EPA/600/13
is.SUPPLEMENTARY NOTES APpcD 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.	
16. ABSTRACTrj-ne paper gives results of experiments to explore the relationships between
 the insecticide chlorpyrifos and its distribution into  carpet,  carpet dust, and reemis
 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 obsefved^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
                                             COSATI Field/Group
 Pollution
 Carpets
 Dust
 Aerosols
 Insecticides
 Ventilation
                  Pollution Control
                  Stationary Sources
                  Chlorpyrifos
                  Indoor Air
13 B
HE
11G
07D
06F
13A
18. DISTRIBUTION STATEMENT
 Release to Public
                                           19. SECURITY CLASS (This Report}
                                           Unclassified
                                                                    21. NO. OF PAGES
                 20. SECURITY CLASS (This page)
                  Unclassified
                                          22. PRICE
EPA Form 2220-1 (9-73)

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