United States
Environmental Protection
Agency
Atmospheric Research and
Exposure Assessment Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-94/189 November 1994
EPA Project Summary
Development and Evaluation of
Monitoring Methods for
Polycyclic Aromatic
Hydrocarbons in House Dust and
Track-In Soil
Jane C. Chuang, Patrick J. Callahan, Vanessa Katona, and Sydney M. Gordon
The analytical method for determin-
ing polycyclic aromatic hydrocarbons
(PAHs) in dust and soil consists of
sonication with 10 mL of hexane (C6)
for two 30-min extractions and analy-
sis of the C6 extract by gas chromatog-
raphy/mass spectrometry (GC/MS). The
analytical method for determining poly-
chlorinated biphenyls (PCBs) in dust
and soil involves sonication with 10
mL of 10 percent ether in C6 for two
10-min extractions, silica gel column
chromatography, and analysis of the
target fraction by GC/MS. Quantitative
recoveries of spiked perdeuterated PAH
and 13C-!abeled PCB are obtained us-
ing the above methods.
The sum of the concentrations of all
target PAH In the house dust samples
evaluated in this study ranged from 16
to 580 ppm. Higher concentrations were
observed in entryway soil samples, and
the sum of the concentrations of target
PAH ranged from 68 to 4000 ppm and
58 to 5500 ppm in samples collected
before (October 1992) and after (April
1993) the winter heating season, re-
spectively. The sum of the concentra-
tions of PAH in the pathway soil
samples varied from 3.0 to 1200 ppm
in samples collected before the heat-
ing season (October 1992). The sum of
the concentrations of PAH ranged from
0.58 to 610 ppm and from 0.63 to 63
ppm in pathway soil and foundation
soil samples collected after the heat-
ing season (April 1993), respectively.
The concentrations of most 4- to 6-ring
PAH, the sum of all target PAH, and the
sum of PAHs that are probable human
carcinogens in house dust correlated
well with the corresponding levels in
entryway soil. However, there was no
correlation between the PAH concen-
trations in house dust and in pathway
soil, nor was any relationship found
between house dust and foundation
soil.
The PCB concentrations in house
dust, entryway soil, pathway soil, and
foundation soil were lower than the PAH
concentrations in these samples. The
sum of the concentrations of all target
PCB varied from 210 to 1900 ppb in
house dust, from 30 to 880 ppb in
entryway soil, from 16 to 500 ppb in
pathway soil, and from 18 to 210 ppb
in foundation soil. Higher PCB concen-
trations were found in house dust
samples than in entryway soil samples.
Similar PCB concentrations were ob-
served in pathway soil samples and
foundation soil samples, which are
lower than the PCB found in entryway
soil samples. The concentrations of
penta-PCB, hexa-PCB, and the sum of
all target PCB in house dust correlated
well with corresponding levels in
entryway soil. However, this relation-
ship was not observed for the PCB
concentrations in house dust and path-
way soil, nor was there any discernible
relationship between the PCB concen-
trations in house dust and foundation
soil samples.
This report is submitted in fulfillment
of Contract Number 68-DO-0007, Work
Assignment No. 35, Task 1, by Battelle
under the sponsorship of the U.S. En-
vironmental Protection Agency. This
report covers the period between June
1992 and September 1993. Work was
completed as of September 1993.
Printed on Recycled Paper
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This Project Summary was developed
by EPA's Atmospheric Research and
Exposure Assessment Laboratory, Re-
search Triangle Park, NC, to announce
key findings of the research project that
Is fully documented In a separate report
of the same title (see Project Report
ordering Information at back).
Introduction
Recant studies to develop suitable sam-
pling and monitoring techniques for estab-
lishing human exposure to pesticides have
suggested that relatively high levels of
pesticide residues may occur in house
dust. Residues tracked into the home may
remain in carpets for prolonged periods
due to the absence of environmental
weathering effects. These residues may
be picked up by the skin on contact. Once
on the skin, the pesticides may be ad-
sorbed directly or transferred to the mouth
and ingested. Because young children
spend a great deal of time on the floor,
they are particularly susceptible to expo-
sure to these chemicals as a result of
dermal contact with house dust and the
frequent hand-to-mouth contact that ac-
companies their normal play activities. An
estimate of average daily soil and dust
ingestfon by young children ranges from
0.02 to 0.2 g, with a potential for up to 5 g
per day for children exhibiting pica behav-
ior who live in a dusty home or have
access to exposed soil.
PAHs and PCBs represent two impor-
tant groups of semivolatile organic com-
pounds (SVOCs) that have been found in
indoor and ambient air. Many PAHs are
known to be carcinogens or mutagens,
and adverse health effects have been
linked to exposure to PAH. The presence
of environmental tobacco smoke has been
shown to be the most important indoor
source of PAH in air. Other indoor activi-
ties that may contribute to PAH concen-
trations in indoor air are grilling of foods,
the use of gas cooking and heating appli-
ances, the use of fireplaces or woodstoves,
the use of unvented kerosene space heat-
ers, and the intrusion of contaminated
ambient air. The levels of PCB in indoor
air have been found to be higher than in
outdoor air in several studies. Defective
fluorescent light ballasts are suggested as
one important indoor PCB source.
Higher PAH levels have been found in
dust or soil samples taken near heavy
traffic. Therefore, homes located down-
wind of heavy traffic may have higher
PAH levels in house dust than those in
lighter traffic areas. Very little information
Is available, however, about the occur-
rence and distribution of PAH and PCB in
house dust resulting from indoor sources
or from track-in of outdoor dislodgeable
soil residues. Data also suggest a pos-
sible magnification of lead (Pb) in soil
near foundations. If such magnification
near the foundation occurs, it may be due
to the deposition of atmospheric Pb on
the roof and the outside surfaces of the
house, which then falls or washes down
to the soil near the drip line of the roof. It
is not clear whether such magnification
also occurs with SVOCs, such as PAH
and PCB.
Objectives
There are no established monitoring
methods for PAH and PCB in house dust
and track-in soil. Therefore, this study was
undertaken to evaluate monitoring meth-
ods for PAH and PCB in dust and soil
samples. The specific objectives of the
study were
1) to evaluate and validate analytical
methods for measuring PAH and
PCB in dust and soil samples;
2) to obtain concentration profiles for
PAH and PCB in dust and soil
samples from an eight-home pilot
field study conducted in Columbus,
Ohio, before and after the 1992-
1993 heating season;
3) to determine whether track-in of
outdoor soil residues is an impor-
tant source of PAH and PCB in
house dust; and
4) to determine whether magnification
of PAH and PCB levels occurs in
the foundation soil.
This study was carried out in two phases
to accomplish the above objectives:
Phase I—Validate analytical meth-
ods for determining PAH and PCB
in house dust and soil samples;
• Phase II—Conduct a small-scale
pilot field study.
Procedures
Two extraction methods, Soxhlet extrac-
tion and sonication, were evaluated and
validated for removing PAH and/or PCB
from dust and soil sample matrices. The
analytical method validated for determin-
ing PAH in house dust and soil samples
consists of sonical extraction of the sample
with C6 and GC/MS analysis. The vali-
dated analytical method for determining
PCB in dust and soil samples consists of
1) sonical extraction of the sample with
10 percent ether in C6)
2) silica gel fractionation of the sample
extract, and
3) GC/MS analysis of the target frac-
tion.
A small-scale pilot field study was con-
ducted before and after the 1992-1993
heating season by collecting and analyz-
ing house dust and soil samples from
eight homes. The first sampling session
took place in June 1992 when only house
dust samples were collected. The second
sampling session occurred in October
1992. At each home, house dust, entry way
dirt, and pathway soil samples were col-
lected. During the third sampling session
in April 1993, house dust, entryway dirt,
pathway soil, and foundation soil samples
were collected from each home. The dust
and soil samples were prepared by the
methods validated for PAH and PCB analy-
sis.
Results
Quantitative recoveries (> 80 percent)
of the spiked perdeuterated PAH were
obtained when either DCM or C? were
used as the extraction solvent with the
Soxhlet technique. Both DCM and C6 ef-
fectively remove PAH from the dust and
soil samples, but the silica gel cleanup
step is not required when Ce is used.
Therefore C6 was used as the extracting
solvent in the experiments to evaluate dif-
ferent sonication conditions. Quantitative
recoveries were obtained when the
samples were sonicated twice with C6 for
30 minutes. The recoveries in this experi-
ment ranged from 91 percent for
fluorene-d10 to 100 percent for pyrene-d,0.
This sonication condition was used with
the spiked soil samples, and recoveries
ranged from 91 percent (fluorene-d,0) to
98 percent (benzo(k)fluoranthene-d,2). The
precision for measuring native PAH in trip-
licate samples was within 15 percent (rela-
tive standard deviation) with this sonication
method. In summary, the analytical method
adopted consists of extracting the sample
twice by sonication with 10 mL of C6 and
analyzing the concentrated C6 extract by
GC/MS to determine the target PAH. The
two 30-minute sonications with C6 offer
the best recoveries for perdeuterated PAH
in spiked dust and soil samples but not for
spiked 13C-labeled PCB. Approximately 50
percent of each spiked 13C-labeled PCB
was recovered using this method. Experi-
ments were then carried out using a more
polar solvent, 10 percent ether in C6. In
summary, the analytical method used con-
sists of extracting the samples twice by
sonication with 10 mL of 10 percent ether
in C6 for 10 minutes, fractionating the ex-
tract on a silica gel column, and analyzing
the target fraction by GC/MS.
In the pilot field study, the average PAH
concentrations in house dust samples were
less than 1 ppm for most 2- to 3-ring PAH
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and greater than 10 ppm for most 4- to
6-ring PAH. Among the measured target
PAH, the most abundant PAHs found in
these house dust samples were 4-ring
(fluoranthene and pyrene) and 5-ring
(benzofluoranthenes and benzo(a)pyrene)
PAH. The least abundant PAHs found in
these samples were, in general, the vola-
tile 2-ring PAH and the reactive PAH such
as acenaphthylene and cyclopenta-
(c.d)pyrene. Note that naphthalene con-
centrations were less than 1 ppm from
samples collected in June 1992 and April
1993, but the concentrations were greater
than 1 ppm from samples collected in
October 1992. The low concentrations of
acenaphthylene and cyclopenta(c,d)pyrene
in house dust samples are partly due to
the reactivities of these compounds. As
demonstrated in previous studies,
acenaphthylene and cyclopenta(c,d)pyrene
can oxidize to naphthalene dicarbonylic
• acid anhydrides and pyrene dicarbonylic
acid anhydrides, respectively. The highest
PAH concentrations in dust were found in
samples collected from a nonsmoker's
house (H08) for all three sampling events.
In this house, similar PAH concentrations
were obtained from house dust samples
collected before the heating season (June
1992 and October 1992). Relatively lower
PAH concentrations were observed in the
house dust sample collected after the heat-
ing season (April 1993). The concentra-
tions of the well known carcinogen,
benzo(a)pyrene (BaP) in this house were
54, 44, and 24 ppm in house dust samples
collected during June 1992, October 1992,
and April 1993, respectively. The PAH
concentrations in dust samples collected
from the smokers' houses (HOI, H04, H05,
and H06) were not always higher than
those from the nonsmokers' houses. This
finding suggests that the presence of en-
vironmental tobacco smoke (ETS) is not
the only source for PAH in house dust.
The sum of the concentrations of the seven
B-2 PAH (probable human carcinogen)
were 10 to 300 ppm in the dust samples
collected before the heating season (June
1992 and October 1992) and 13 to 160
ppm in the samples collected after the
heating season (April 1993). These levels
are well above the 1 ppm level that the
Washington State Model Toxics Control
Act sets as standard for the B-2 PAH for
residential soil at hazardous waste sites.
Note that the sum of the concentrations of
B-2 PAH are approximately half of the
total concentrations of all 19 target PAHs
(2- to 6-ring) in all but four samples col-
lected during the three sampling sessions.
The most abundant and least abundant
PAH in entryway soil are similar to those
found in house dust. The concentrations
of target PAH were higher in entryway soil
in samples compared to house dust
samples. The PAH concentrations found
in entryway soil in samples collected be-
fore the heating season are within the
same order of magnitude as levels in the
samples collected after the heating sea-
son. The highest PAH concentrations in
entryway soil samples were from House
H08, which also showed the highest PAH
concentrations in house dust samples. The
BaP concentrations in entryway samples
from House H08 were 350 and 380 ppm
before and after the heating season,
respectively. The sum of the concen-
trations for B-2 PAH were also about half
of the sum of the concentrations for all 19
PAHs in most entryway soil samples. We
also investigated the relationship between
the measured PAH concentrations in
house dust and entryway soil samples to
determine whether any correlation exists
between the PAH levels in these samples.
A linear regression analysis was performed
on each measured target PAH to deter-
mine the correlation coefficient (R2). Stron-
ger relationships were observed for B-2
PAH (probable human carcinogens), other
nonvolatile 4- to 6-ring PAHs, and the
sum of all PAHs. As expected, the volatile
PAH and reactive PAH showed weaker
relationships. These results suggest that
the effect of track-in from the door mat is
an important source of PAH in house dust.
The PAH concentrations found in path-
way soil samples were lower than the
levels in house dust and entryway soil
samples. The least and most abundant
PAH found in pathway soil samples were
similar to house dust and entryway soil
samples. Higher PAH concentrations were
found in pathway soil samples collected
before the heating season (October 1992)
compared to those collected after the heat-
ing season (April 1993) for all but one
household. The average concentrations
from the eight houses sampled ranged
from 0.059 ppm of naphthalene to 36 ppm
of pyrene before the heating season, and
from 0.023 ppm of naphthalene to 16 ppm
of fluoranthene after the heating season.
The fact the House H08 showed the high-
est PAH concentrations in entryway soil
and house dust samples may have been
caused by the pathway soil samples in
this house having been taken along the
driveway, the major walkway of the house.
The homeowner paved the driveway ap-
proximately 2 weeks before the October
1992 sampling session.
The average PAH concentrations in the
foundation soil samples ranged from 0.023
ppm of naphthalene to 3.3 ppm of
fluoranthene. Levels of PAH found in the
foundation soil samples were lower than
the levels in the pathway samples for all
but one house (H05). The PAH concen-
trations in the foundation soil from House
H08 were not one of the highest levels of
all the foundation soil samples. This can
be partly expjained by the fact that the
foundation soil sample from House H08
was taken from the driveway. The sources
of the extremely high levels of PAH in
house dust, entryway soil, and pathway
soil from this house (H08) are not under-
stood clearly yet. In general, the relative
concentration trend for target PAH is
entryway soil > house dust > pathway >
foundation soil.
The most abundant PCB found in house
dust entryway soil, pathway soil, and foun-
dation soil samples are. penta-PCB, and
the least abundant PCB was the most
volatile mono-PCB. None of the nona-PCB
and deca-PCB were found in these
samples. The concentrations of penta-PCB
ranged from 71 to 950 ppb in house dust
samples, from 10 to 520 ppb in entryway
soil samples, from 4.6 to 280 ppb in path-
way soil samples, and from 7.5 to 87 ppb
in foundation soil samples. The highest
PCB concentrations in the house dust,
entryway soil, pathway soil, and founda-
tion soil samples are from House H03.
Unlike PAH, the highest PCB concentra-
tions were found in house dust samples
followed by entryway soil samples. Simi-
lar PCB concentrations were found in path-
way soil and foundation soil samples. We
conducted a linear regression analysis on
the measured PCB concentrations from
house dust and entryway soil samples.
The concentrations 'of penta-PCB,
hexa-PCB, and total PCB show strong
correlations between house dust samples
and entryway soil samples. Weaker rela-
tionships were observed for mono-, di-,
tri-, and tetra-PCB, which are probably
due to the low concentrations for these
PCBs in most of the samples. There is no
correlation between the PCB concentra-
tions in house dust and pathway soil, nor
can any significant relation be established
between house dust and foundation soil
samples. This is probably due to differ-
ences in environmental weathering effects
between pathway and foundation soil on
the one hand and between entryway soil
and house dust on the other.
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Conclusions and
Recommendations
An analytical method consisting of
sonlcal extraction of the sample with C6
and GO/MS analysis was validated for
determining PAH in house dust and soil
samples. With this method, the spiked
PAHs were quantitatively recovered from
dust and soil samples. The recoveries
ranged from 91 (fluorene-d10) to 100
(pyrene-d10) percent in the dust samples
and from 91 (fluorene-d,0) to 98
(banzo(k)fluoranthene-d12) percent in the
soil samples.
An analytical method for determining
PCB in the dust and soil samples was
validated. This method consists of
1) sonical extraction of the sample with
10 percent ether in C6,
2) silica gel fractionation of the sample
extract, and
3) GO/MS analysis of the target frac-
tion.
The recoveries of spiked 13C-labeled PCB
ranged from 91 (4-chlorobiphenyl (13C6)) to
99 percent (3,3',4,4'-tetrachlorobiphenyl
(13C«)) in the dust samples and from 90
(2,2', S.S'.S.S'.e.e'-octachlorobiphenyl (13C12))
to 93 percent (3,3',4,4'-tetrachlorobiphenyl
("0,2)) In the soil samples.
The sum of the target PAH concentra-
tions in house dust ranged from 16 to 580
jig/g (ppm) in samples collected before
the 1992-1993 heating season and from
25 to 310 ppm in samples collected after
the heating season. PAH concentrations
were higher in entryway soil samples than
in the corresponding house dust samples.
The sum of PAH concentrations in
entryway soil samples ranged from 66 to
4000 ppm and 58 to 5500 ppm in samples
collected before and after the heating sea-
son, respectively. The sum of PAH con-
centrations ranged from 3.0 to 1200 ppm
and 0.58 to 610 ppm in pathway soil
samples collected before and after the
heating season, respectively. The sum of
PAH concentrations in foundation soil
samples collected after the heating sea-
son ranged from 0.63 to 63 ppm.
The concentrations of those PAHs that
are probable human carcinogens (desig-
nated as. B-2 PAH) account for roughly
half of the concentrations of the sum of all
target PAHs in most dust and soil sam-
ples. With few exceptions, the general con-
centration trend for the PAH in the house
dust samples was entryway soil > house
dust > pathway soil > foundation soil. The
concentrations of the 4- to 6-ring PAH,
B-2 PAH, and the sum of all target PAH in
entryway soil samples correlate well with
the corresponding levels in house dust
samples. However, there is no correlation
between the PAH concentrations in house
dust and in pathway soil samples. Nor
does any relation exist between the PAH
concentrations in house dust and in foun-
dation soil samples. This absence of a
relationship is probably due to differences
in environmental weathering effects on
pathway and foundation soils compared
with the effects on house dust and
entryway soils. The effect of track-in could
be a significant factor contributing to PAH
levels in house dust, and more studies
are needed to investigate this factor. The
presence of environmental tobacco smoke
is not the only important source of PAH in
house dust. Furthermore, there is no evi-
dence that PAH magnification occurs in
foundation soil samples.
The sum of the target PCB concentra-
tions in house dust samples varied be-
tween 210 and 1900 ng/g (ppb) and, in
entryway soil samples, ranged from 30 to
880 ppb. The sum of the PCB concentra-
tions ranged from 16 to 500 ppb and from
18 to 210 ppb in pathway soil and founda-
tion soil samples, respectively. All these
samples were collected during April 1993.
The PCB concentrations are lower than
the PAH concentrations in all house dust,
entryway soil, pathway soil and founda-
tion soil samples. Unlike PAH, the general
concentration trend for PCB was house
dust > entryway soil > pathway soil. Simi-
lar PCB concentrations were found in path-
way soil and foundation soil samples. As
in the case of the PAH, there is no evi-
dence of PCB magnification occurring in
foundation soil. The concentrations of
penta-PCB, hexa-PCB, and total PCB
house dust samples correlate well with
those in entryway samples. However, there
is no significant correlation for mono-, di-,
tri-, and tetra-PCB concentrations in house
dust and entryway soil samples, which is
probably due to the low concentrations of
these PCB compounds. There is also no
correlation between the sum of the PCB
concentrations in house dust and path-
way soil samples. Furthermore, there is
no relationship between the PCB concen-
trations in house dust and in foundation
soil.
There are several important issues that
remain to be addressed in order to as-
sess exposure due to house dust and
soil. In future studies, we recommend
1) Measuring the PAH in house dust,
entryway soil, pathway soil and
foundation soil in a sufficiently large
sample of homes located in the
same community as House H08 in
this study, in order to investigate
whether the high PAH concentra-
tions observed in the house dust
and soil at this house are also found
in these samples.
2) Conducting a similar study in a city
in a colder climate with a history of
coal burning.
3) Conducting a similar study in a city
in a mountain valley with a history
of wood burning.
4) Conducting a similar study in a city
with heavy traffic.
5) Determining the effect of track-in
and dust control techniques on ex-
posure to PAH in house dust.
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