THE DISTRIBUTION OF CHLORPYRIFOS FOLLOWING A CRACK
AND CREVICE TYPE APPLICATION IN THE U.S. EPA INDOOR AIR
QUALITY TEST HOUSE.
DM Stout II1 and MA Mason2
'U.S. EPA National Exposure Research Laboratory, Human Exposure and Analysis Branch,
Research Triangle Park, NC 27711, (919) 541-5767, stout.dan@epa.gov.
2U.S. EPA National Risk Management Research Laboratory, Indoor Environment
Management Branch, Research Triangle Park, NC 27711, (919) 541-4835.
ABSTRACT
A study was conducted in the U.S. EPA Indoor Air Quality Test House to determine the
spatial and temporal distribution of chlorpyrifos following a professional crack and crevice
application in the kitchen. Following the application, measurements were made in the kitchen,
den and master bedroom over 21-days. Airborne concentrations were collected using both
polyurethane foam (PUF) and a XAD/PUF (OVS) media. Measured airborne concentrations
were similar for the two samplers, were higher in the three rooms following the application,
reached maximal levels 24-h post-application, and declined steadily over the 21 -day study
period. Spatial and temporal distributions were measured using 10-cm2 cotton deposition
coupons. Sections were cut from existing carpet to determine the total extractable residues.
Chlorpyrifos was measured from all matrixes in the kitchen, den and bedroom and shows the
transport of airborne residues from the point of application to remote locations in the house.
INDEX TERMS: Chlorpyrifos, Translocation, Pesticide, Residential exposure.
INTRODUCTION
Pesticides are applied in and around human habitations to control a variety of pests and may
place toxicants in close proximity to humans. 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 the
compounds physiochemical properties (i. e,, the vapor pressure of the active ingredient and
formulation type), the substrate that deposits contact, and the physical activities of humans
and pets. Pesticide residues found indoors are less influenced by degrading factors such as
photolysis and microbial activity. 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 (Lewis and MacLeod,
1982). Exposure to indoor pollutants such as pesticides may pose risks to occupants through
inhalation, dermal absorption, and direct or indirect ingestion.
A pilot experiment was conducted in the U. S. EPA's Indoor Air Quality Test House to
investigate the contribution of a crack and crevice application of the insecticide chlorpyrifos
to airborne residue levels in the home. In addition, the deposition of airborne residues onto
deposition coupons and indoor carpeting was discussed. Chlorpyrifos is no longer registered
for indoor, residential crack and crevice applications. However, these data are relevant to
understanding the relationships between indoor applications of semi-volatile pesticides and
the movement of like compounds in the indoor environment, and the potential for human
exposure.

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METHODS
The Test House
The study reported here was conducted in November 2000, in the U.S. EPA's Indoor Air
Quality 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 interior
volume of the test house contains a total 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 defined in that air exchange rates, temperature,
and relative humidity are continuously monitored. The rooms are open to the entry hallway
and the kitchen (Figure 1) and their physical separation is only partial. The kitchen is open to
the den via a "pass-through opening".
Master
Bedroom
a
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Clos Clos
Clos
EP
Master
Bath
Bath
Clos
(L) Dmi
(C)B*
(R)m
© BP
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¦ © ¦
Clos Utilit)
Corner
Bedroom
Middle
Bedroom
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Kitchen
Living Room
Clos
Instruments
Garage
PUF Air Sampler	©
Carpet Sections	B
Deposition Coupon ¦
LEFT	(L)
CENTER	(C)
RIGHT	(R)
Pass Through 	
(NOT TO
SCALE)
Figure 1. Overview of the IAQ Test House with the sample locations shown.
The Pesticide Application
A 0.5% solution of chlorpyrifos [0,0-diethyl-0-(3,5,6-trichloro-2-pyridinyl)
phosphorothioate] was prepared as per label directions by diluting 78 mL of a commercially
available, emulsifiable concentrate formulation with 3700 mL of tap water in a pre-cleaned 1-
gallon compressed air sprayer. A total of 259 mL of the finished solution was applied in the
kitchen only (Figure 1) theoretically providing
1.29 g of active ingredient applied. The applications were performed by a licensed pest
control operator using a compressed air sprayer operated at 30 psi and equipped with pin-
stream-type spray tip. The application simulated a "clean-out" type treatment that is
conventional for the control a cockroach infestation. Here the dilute solution is systematically
placed into the potential cockroach harborages such as the cracks and crevices of the
cabinetry, and around and behind the stove, refrigerator and dishwasher.
Prior to the application, all windows were closed and the furnace fan was turned off.
Afterwards, the house thermostat was set to 22 °C (72 °F) for the duration of the experiment.
The interior doors remained open throughout the test.
Air Monitoring
Air monitoring was conducted using both commercially available Polyurethane Foam (PUF)
tubes and the OSHA Versatile Sampler or OVS tubes (SKC Inc., Eighty-Four, PA). The PUF

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tube was a 76 by 20-mm PUF plug in glass filter housing. The PUF system was open faced
with no particle cutoff inlet. The OVS tube consisted of a 74 by 13-mm glass housing
containing a quartz filter and two 140 and 270 mg beds of XAD-2 sandwiched between PUF
partitions. Both monitors were suspended 100-cm above the floor in the living room, den and
the master bedroom (Figure 1). The tubes were connected by Tygon tubing to SKC Universal
XR sample pumps. The pumps were calibrated to a flow rate of 3.8 and 1.0 L/min for PUF
and OVS, respectively. Air was drawn over the media for a period of 24-h. The sample inlets
were directed towards the floor. Samples were collected prior to the application and at days 1,
3, 7, 14 and 21 days post-application. Following sample collection, the PUF and OVS tubes
were capped with aluminum foil and individually sealed in plastic bags. The tubes were put in
ice chests at reduced temperatures for transport.
Deposition Coupons
Johnson and Johnson Sof-Wick Surgical Sponges (100 cm2) were used to determine the
surface deposition of airborne chlorpyrifos following the application. Each deposition coupon
consisted of a surgical sponge backed by solvent rinsed aluminum foil. The deposition
coupons were placed on the floor in the kitchen, den, and bedroom (Figure 1) and collected
prior to, immediately following the application, and at days 3, 7, 14 and 21 days post-
application. At each sampling interval, the deposition coupons were collected and replaced
with a new coupon. Coupons were individually collected immediately following the
application in the kitchen and den, but were aggregated in the bedroom. At all other sampling
intervals, the deposition coupons in the kitchen and den were aggregated by rows across the
length of the room, except in the bedroom where all five coupons were aggregated. The
samples were collected using clean, solvent-rinsed forceps, placed in labeled glass jars
equipped with Teflon lined lids, and stored in ice chests at reduced temperatures for transport.
Carpet Sections
Prior to the insecticide treatment, 16 cm2 carpet sections were precut in the den and master
bedroom (Figure 1). Eight and six groups (consisting of six carpet sections each) were cut
from the den and bedroom, respectively, at locations adjacent to the deposition coupons.
Similar to the deposition coupons, the carpet sections were collected prior to, immediately
following the application, and at days 3,7,14 and 21 days post-application. Each group of
carpet sections remained in place over the course of the study. Samples in the den were
aggregated across rows, while in the bedroom all five samples were aggregated at each
interval. The samples were collected using solvent-rinsed forceps, placed in labeled glass jars,
and stored in ice chests at reduced temperatures for transport.
Chemical Analysis
The samples were extracted using Soxhlet or shake techniques in a solvent of 5% diethyl
ether/hexane. Samples were analyzed using a Hewlett-Packard 5890 gas chromatograph
equipped with a liquid auto-sampler and electron capture detector. A DB-5 fused silica
column (30 m X 0.25 mm) was used for quantitation. The carrier flow rate was 2.0 mL/min.
The temperature program was initiated at 125°C and ramped to 200 °C at 4 °C /min and
ramped from to 290 °C at 8 °C /min. The capillary injector was operated in the splitless mode
for 1-min. Injector and detector temperatures were 240 and 300 °C, respectively.
Other Test House Measurements
The air exchange rates were determined by using the tracer gas decay technique.
Temperatures were measured in all rooms and outdoors and the relative humidity was

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measured in selected rooms and outdoors. Meteorological conditions were measured with a
system on-site. Data for the environmental measurements were recorded continuously during
the study, but are not reported here.
Quality Control
Laboratory quality control included matrix blanks, spikes and duplicates of PUF, OVS, and
deposition coupons and carpet sections. Field quality control was similar, but did not include
carpet spikes. Chlorpyrifos was not detected from any of the laboratory or field blank
samples. Fortified spikes containing 100 ng of chlorpyrifos provided recovery efficiencies
(mean ± SD) for field control samples of PUF, OVS, and deposition coupons of 114±12,
103±11%, and 98±8%, respectively. Laboratory control samples of PUF, OVS, deposition
coupons and carpet sections fortified at a similar level provided recovery efficiencies of
122±9, 115±12%, 104±11% and 120±6%, respectively.
RESULTS AND DISCUSSION
Airborne Concentrations
Airborne concentrations of chlorpyrifos measured using PUF and OVS samplers agreed well
(Table 1). Very low levels of chlorpyrifos were measurable as background. Maximal
chlorpyrifos levels were recovered from both type filters at day 1 (24-h following the
application) and declined by more than 70% by day 21. Chlorpyrifos was detected in all
rooms at each sampling interval at levels above background. Measured levels were highest at
the source and declined as the distance from the source increased.
Table 1. Airborne chlorpyrifos residues collected on PUF and OVS samplers following a
crack and crevice type application in the IAQ test house.
Concentration (|ig/m )
Sampler Type
Room
Pre
la
3
7
14
21
PUF
Kitchen

0.79
0.77
0.32
0.22
0.14

Den
0.003
0.25
0.14
0.09
0.06
0.07

Bedroom

0.10
0.07
0.06
0.04
0.03
OVS
Kitchen

1.0
0.62
0.34
0.34
0.18

Den
0.02
0.33
0.15
0.09(0.08)b
0.06
0.06(0.05)b

Bedroom

0.09(0.14)"
0.06
0.05
0.04
0.03
a Air sampling was initiated immediately following the application and monitored
continuously for 24-h. b The value in brackets represents a field duplicate sample.
Deposition Coupons
Field and laboratory blanks showed no chlorpyrifos and represent pre samples. Chlorpyrifos
concentrations measured from deposition coupons in the kitchen immediately following the
application were highly variable (Table 2). Concentrations were highest at the floor/cabinetry
junction and lowest along the center row. Measurements collected from deposition coupons
located in the den were relatively uniform except for two deposition coupons with high levels
located along the wall that adjoins the kitchen. Average concentrations (Table 3) measured
from the three rooms show a positive contribution of chlorpyrifos from the kitchen (source)
onto the deposition coupons in both the den and bedroom. The chlorpyrifos recovered from
the deposition coupons in the kitchen and den decreased as the distance from the source
increased. In addition, chlorpyrifos measured from the deposition coupons in all rooms
similarly declined over time.

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Table 2. Chlorpyrifos concentrations measured from deposition coupons in the den and
kitchen immediately following a crack and crevice application	
Concentration (jig/100 cm )/ Location in Room
Room
Row
1
2 3
4
Den
Left
0.07
0.09 0.08
0.08

Center
0.09
0.08 0.07
0.07

Right
0.24
1.44 0.06
0.07
Kitchen
Left
0.94
17.86 1.77
22.91

Center
1.19
0.41 0.66
0.66

Right
0.15
5.88 0.59
5.19
Table 3. Average concentrations of chlorpyrifos measured from deposition coupons in the
kitchen, den and bedrooms at intervals following a crack and crevice application.



Concentration p.g/100 cm2 / Room

Day

Kitchen
Den
Bedroomb
la

4.85 ±7.57c
0.20 ±0.39
0.01
3

3.53 +2.46
0.34 ±0.03
0.13
7

1.48 ±0.46
0.25 ±0.05
0.08
14

0.52 ±0.32
0.19 ±0.04
0.17
21

0.36 ±0.44
0.19 ±0.04
0.55
a The samples were collected immediately following the application.b The value represents
the aggregation of five samples.c The value following the concentration represents ±SD.
Carpet Sections
The finding show a higher than anticipated pre-application levels of chlorpyrifos in the
existing carpet (Table 4) and a non-homogenous distribution of chlorpyrifos throughout the
study. The highest but most variable values were measured from the center of the den.
Samples collected from the right and left rows suggest an increase in concentration over time.
Background levels were detected in the bedroom, but increase concentrations suggest a
possible contribution from the application. Background levels may have been associated with
intrusion from sources not associated with this application.
Table 4. Chlorpyrifos measured from carpet sections from three locations in the den and the
bedroom following a crack and crevice application in the IAQ Test House.
Location/ Concentration (jag/100 cm2)
Den
Day
Left
Center
Right
Bedroom3
Pre
1.18
9.83
1.72
0.91
lb
1.56
3.51
2.71 (3.03)c
0.89
3
1.77
7.20
2.38
1.10
7
1.78
11.70
3.22
1.14
14
2.11
7.72
3.40
1.25
21
2.51
4.94
4.31
1.25
8 The value represents an aggregation of five samp The samples were collected
immediately following the application.c The value in brackets represents a duplicate field
sample.

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CONCLUSIONS
Crack and crevice type applications in current used by pest control operators locate
insecticides in cockroach harborage sites and minimize human exposure to the residues. Here
chlopryrifos administered to cracks and crevices in the kitchen resulted in airborne vapors and
deposition onto non-target surfaces. The high levels measured from the kitchen floor and in
the den were likely due to the application factors such as over spray and splashing,
Chlorpyrifos, a semi-volatile compound (vapor pressure 1.7 X 10"5 mm Hg at 25 °C), rapidly
distributed within the house. Diffusive processes were important in the immediate dispersion
from the point of application, but the active HVAC system was also likely a significant factor.
Based on the pesticides distribution throughout the house, many exposed surfaces might be
contaminated and serve as potential sources for human exposure, particularly children playing
on the floor near the point of application. Exposure assessment studies may need to consider
translocation processes when monitoring for semi-volatile insecticides. The high values
detected on deposition coupons and carpet sections suggest that residues persist for a long
time. Exposure estimates may need to evaluate further the persistence of pesticides following
applications indoors beyond 21 days.
Since the inception of this experiment, registrations allowing for the indoor application of
chlorpyrifos have been withdrawn. However, these finding are representative of crack and
crevice applications of a semi-volatile compound and short-term distribution at the point of
application. Pyrethroid insecticides and baits are currently popular in residential pest control.
Transport mechanisms, and spatial distributions are expected to be different and may not be
represent well by these findings. Further experiment are required examining different
application techniques and classes of insecticides to further our understanding of fate,
transport and potential human exposure following residential pesticide applications.
REFERENCES
ASHRAE, ASHRAE Handbook of Fundamentals. American Society of Heating,
Refrigeration and Air Conditioning Engineers, Inc., Atlanta, GA, 1985; p 228.
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.
Lewis, R.G. and MacLeod, K.E., Portable Sampler for Pesticides and Semivolatile Industrial
Organic Chemicals. Anal. Chem. 54, 310-315 (1982).
Mason, M. A.; Sheldon, L. S.; Stout II, D. M. The Distribution of Chlorpyrifos in Air,
Carpeting, and Dust and Its Reemission from Carpeting Following the Use of Total
Release Aerosols in and Indoor Air Quality Test House. In Proceedings of a Symposium,
Engineering Solutions to Indoor Air Quality Problems, Raleigh, NC, July 17-19,2000.
This work has been funded wholly or in part by the United States Environmental Protection
Agency. It has been subjected to Agency review and approvedfor publication. Mention of
trade names or commercial products does not constitute endorsement or recommendation for
use.

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	TECHNICAL REPORT DATA	
16. Abstract
THE DISTRIBUTION OF CHLORPYRIFOS FOLLOWING A CRACK AND CREVICE
TYPE APPLICATION IN THE U.S. EPA INDOOR AIR QUALITY TEST HOUSE. Daniel M.
Stout II1. Mark A. Mason2. (1) U.S. EPA National Exposure Research Laboratory, Human Exposure
and Analysis Branch, Research Triangle Park, NC 27711, (919) 541-5767, stout.dan@epa.gov. (2)
U.S. EPA National Risk Management Research Laboratory, Indoor Environment Management
Branch, Research Triangle Park, NC 27711, (919) 541-4835.
Pesticides found in homes may result from indoor applications to control household pests or by
translocation from outdoor sources. Pesticides disperse according to their physical properties and
other factors such as human activity, residential air exchange, temperature and humidity. A study was
conducted in the U.S. EPA Indoor Air Quality test house to determine the spatial and temporal
distribution of chlorpyrifos following a professional crack and crevice application in the kitchen.
Following the application, measurements were made in the kitchen, den and master bedroom over 21-
days. Airborne concentrations were collected using both polvurethane foam (PUF) and a XAD/'PUF
media. Transferable chlorpyrifos residues were determined using a press sampler and C,g extraction
discs. Spatial distributions, application surface loadings, and redeposition were measured using 10
cm2 deposition coupons. Sections were cut from existing carpet to determine the total cxtractable
residues. Surface wipes were and vacuum dislodgeable residues were collected in the kitchen and
carpeted den, respectively. Measured airborne concentrations were similar for both samplers, detected
in all rooms sampled, reached maximal concentrations 24-hours post-application and steadily declined
by day 21. Concentrations measured from deposition coupons suggest that airborne residues sorbed to
deposition coupons in all rooms sampled. However, carpet sections, due to high background
concentrations of chlorpyrifos, poorly resolve the contribution of the application to carpet residues.
This work has been funded wholly or in part by the United States Environmental Protection Agency. It
has been subjected to Agency review and approved for publication. Mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
17. KEY WORDS AND DOCUMENT ANALYSIS
A. Descriptors
B. Identifiers / Open Ended
Terms
C. COSATI

18. Distribution Statement
19. Security Class (This
Report)
21. No. of Pages
6
20. Security Class (This
Page)
22. Price

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NERL-RTP—heasd-02—oi 9 TECHNICAL REPORT DATA
1. Report No. 2.
EPA/600/A-02/059
3. Recipient's Accession No.
4. Title and Subtitle
THE DISTRIBUTION OF CHLORPYRIFOS FOLLOWING
A CRACK AND CREVICE TYPE APPLICATION IN THE
U.S. EPA INDOOR AIR QUALITY TEST HOUSE.
5. Report Date
6. Performing Organization Code
NERL/HEASD/HEAB
7. Author(s)
Daniel M. Stout II1. Mark A. Mason2.
8. Performing Organization
Report No.
9.Performing Organization Name and Address
(1) U.S. EPA National Exposure Research Laboratory, Human Exposure and
Analysis Branch, Research Triangle Park, NC 27711, (919) 541-5767,
stout.dan(a).eDa.i>ov, (2) U.S. EPA National Risk Management Research
Laboratory, Indoor Environment Management Branch, Research Triangle Park,
NC 27711,(919) 541-4835.
10. Program Element No,
11. Contract/Grant No.
None
12.Sponsoring Agency Name and Address
(1) U.S. EPA National Exposure Research Laboratory, Human Exposure and
Analysis Branch, Research Triangle Park, NC 27711, (919) 541-5767,
stout.dan@eDa.20v.
13. Type of Report and Period
Covered
Conference Proceedings
14.Sponsoring Agency Code
15. Supplementary Notes

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