Estimating risk at a Superfund site using passive sampling devices as biological surrogates in human health risk models

Environmental and Molecular Toxicology Department, Oregon State University, Corvallis, OR, USA.
Chemosphere (Impact Factor: 3.34). 07/2011; 85(6):920-7. DOI: 10.1016/j.chemosphere.2011.06.051
Source: PubMed
ABSTRACT
Passive sampling devices (PSDs) sequester the freely dissolved fraction of lipophilic contaminants, mimicking passive chemical uptake and accumulation by biomembranes and lipid tissues. Public Health Assessments that inform the public about health risks from exposure to contaminants through consumption of resident fish are generally based on tissue data, which can be difficult to obtain and requires destructive sampling. The purpose of this study is to apply PSD data in a Public Health Assessment to demonstrate that PSDs can be used as a biological surrogate to evaluate potential human health risks and elucidate spatio-temporal variations in risk. PSDs were used to measure polycyclic aromatic hydrocarbons (PAHs) in the Willamette River; upriver, downriver and within the Portland Harbor Superfund megasite for 3 years during wet and dry seasons. Based on an existing Public Health Assessment for this area, concentrations of PAHs in PSDs were substituted for fish tissue concentrations. PSD measured PAH concentrations captured the magnitude, range and variability of PAH concentrations reported for fish/shellfish from Portland Harbor. Using PSD results in place of fish data revealed an unacceptable risk level for cancer in all seasons but no unacceptable risk for non-cancer endpoints. Estimated cancer risk varied by several orders of magnitude based on season and location. Sites near coal tar contamination demonstrated the highest risk, particularly during the dry season and remediation activities. Incorporating PSD data into Public Health Assessments provides specific spatial and temporal contaminant exposure information that can assist public health professionals in evaluating human health risks.

Full-text

Available from: Greg James Sower, Oct 16, 2014
Estimating risk at a Superfund site using passive sampling devices
as biological surrogates in human health risk models
Sarah E. Allan, Gregory J. Sower, Kim A. Anderson
Environmental and Molecular Toxicology Department, Oregon State University, Corvallis, OR, USA
article info
Article history:
Received 29 November 2010
Received in revised form 6 June 2011
Accepted 13 June 2011
Available online xxxx
Keywords:
Passive sampling
Public Health Assessment
Polycyclic aromatic hydrocarbons
Bioavailable
Superfund
abstract
Passive sampling devices (PSDs) sequester the freely dissolved fraction of lipophilic contaminants, mim-
icking passive chemical uptake and accumulation by biomembranes and lipid tissues. Public Health
Assessments that inform the public about health risks from exposure to contaminants through consump-
tion of resident fish are generally based on tissue data, which can be difficult to obtain and requires
destructive sampling. The purpose of this study is to apply PSD data in a Public Health Assessment to
demonstrate that PSDs can be used as a biological surrogate to evaluate potential human health risks
and elucidate spatio-temporal variations in risk. PSDs were used to measure polycyclic aromatic hydro-
carbons (PAHs) in the Willamette River; upriver, downriver and within the Portland Harbor Superfund
megasite for 3 years during wet and dry seasons. Based on an existing Public Health Assessment for this
area, concentrations of PAHs in PSDs were substituted for fish tissue concentrations. PSD measured PAH
concentrations captured the magnitude, range and variability of PAH concentrations reported for fish/
shellfish from Portland Harbor. Using PSD results in place of fish data revealed an unacceptable risk level
for cancer in all seasons but no unacceptable risk for non-cancer endpoints. Estimated cancer risk varied
by several orders of magnitude based on season and location. Sites near coal tar contamination demon-
strated the highest risk, particularly during the dry season and remediation activities. Incorporating PSD
data into Public Health Assessments provides specific spatial and temporal contaminant exposure infor-
mation that can assist public health professionals in evaluating human health risks.
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
Urban rivers that are used by local residents for recreational
purposes such as boating, and sport or subsistence fishing are often
heavily polluted. Public Health Assessments inform the public
about the relative risks of these activities in a specific area by pro-
viding information about potential exposures and the likelihood
that those exposures could lead to adverse health effects. A Public
Health Assessment develops an estimated human exposure dose
based on environmental and contaminant data for a specific site
and existing regulatory standards (ATSDR, 2005) (for more infor-
mation about Public Health Assessments please see Section 1 in
Supplementary information). Currently, exposure due to consump-
tion of resident organisms is based on tissue contaminant data
from fish or shellfish harvested in the area. However, obtaining
organisms for analysis can be difficult, usually requires destruction
of the organism and often provides limited specific spatial or tem-
poral information (Huckins et al., 2006). Studies have highlighted
spatial and temporal variations in contamination and exposure
(Ko and Baker, 2004; Brown and Peake, 2006) and others have
called for their consideration in risk assessments (Linkov et al.,
2002). Recently, developing methodology for more accurately
assessing exposure has become a priority for risk assessment
(Birnbaum, 2010). Passive sampling devices (PSDs) can be strategi-
cally deployed to address spatial and temporal issues in bioavail-
able contaminant concentrations, an issue that has been shown
to significantly affect risk (Huckins et al., 2006).
PSDs, such as semipermeable membrane devices (SPMDs), sim-
ulate biological membranes and lipid tissue and thus sequester
only the freely-dissolved or bioaccessible fraction of lipophilic or-
ganic contaminants. Huckins et al. (2006) reviewed over 30 studies
with side-by-side comparisons of SPMDs with organisms and
found good correlations with finfish and bivalves, though few
studies have investigated PAHs specifically (Peven et al., 1996;
Baussant et al., 2001; Verweij et al., 2004; Boehm et al., 2005; Ke
et al., 2007). Correlations between PAHs in SPMDs and organisms
0045-6535/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.chemosphere.2011.06.051
Abbreviations and definitions: PSD, passive sampling device; LFT, lipid-free
tubing PSD; RM, River Mile on the Willamette River, Oregon. River miles are
measured from the confluence of the Willamette River with the Columbia River;
P
16
PAH, sum of 16 PAH compounds.
Corresponding author. Address: Environmental and Molecular Toxicology
Department, Oregon State University, ALS 1007, Corvallis, OR 97331, USA. Tel.: +1
541 737 8501; fax: +1 541 737 0497.
E-mail address: kim.anderson@oregonstate.edu (K.A. Anderson).
Chemosphere xxx (2011) xxx–xxx
Contents lists available at ScienceDirect
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journal homepage: www.elsevier.com/locate/chemosphere
Please cite this article in press as: Allan, S.E., et al. Estimating risk at a Superfund site using passive sampling devices as biological surrogates in human
health risk models. Chemosphere (2011), doi:10.1016/j.chemosphere.2011.06.051
Page 1
have been found in terrestrial and aquatic systems, although inves-
tigators observed differences in the composition of the PAHs
sequestered by organisms and PSDs (Baussant et al., 2001; Ke
et al., 2007; Tao et al., 2008). Baussant et al. (2001) found that low-
er molecular weight PAHs predominated in caged finfish while Ke
et al. (2007) measured higher concentrations of PAHs in SPMDs
compared to tissue from caged carp. While these studies demon-
strate that PSD concentrations can be correlated to organism tissue
concentrations, they do not link the PSD concentrations to human
health risks.
Recent lab and field trials have resulted in simpler and cheaper
variants of SPMDs (Adams et al., 2007; Sower and Anderson, 2008;
Allan et al., 2009). These PSDs are constructed from low density
polyethylene lay-flat tubing without triolein and designated li-
pid-free tubing samplers, or LFTs. PSDs, such as the LFT used in this
study, offer numerous advantages over using organisms for envi-
ronmental assessment including simplicity, low cost, fast and min-
imal extraction and clean-up procedure, no metabolic activity and
no organisms are destroyed. Though numerous physical, physio-
logical and ambient factors affect concentrations in organisms, all
accumulate contaminants like PSDs: from water across biological
membranes (Huckins et al., 2006). Also, unlike organisms, PSDs
spiked with performance reference compounds provide chemical
specific calibrations of time-integrated, bioavailable concentra-
tions that can be standardized across studies (Huckins et al.,
2006; Adams et al., 2007). Using PSDs to determine the time inte-
grated water concentration of contaminants is well established,
however, this is the first demonstration of the direct application
of PSD data for assessing potential human health risks from
consumption.
PSDs are particularly useful in areas where point sources are
significant contributors to contamination and where seasonal fluc-
tuations in contaminant concentrations are suspected. To this end,
the Portland Harbor Superfund megasite on the Willamette River
in Portland, Oregon (river miles or RM 3.5–9.2) is an ideal model
system for examining the application of PSD data to Public Health
Assessments to elucidate potential exposures and risks in an urban
river. Portland Harbor is an industrialized area containing several
PAH point sources including coal tar and a remediated former cre-
osoting plant, which is its own Superfund site within the larger
harbor site. Additional sources of PAHs in the lower Willamette in-
clude ship, train and vehicle emissions, combined sewer overflows,
urban runoff, atmospheric deposition and petroleum product leaks
and spills. Additionally, significant seasonal flow and precipitation
fluctuations occur on the river and seasonal variations in contam-
ination concentrations have been observed (Sower and Anderson,
2008).
The Willamette River is used extensively for both sport and sub-
sistence fishing. Eating contaminated fish from the harbor is con-
sidered the most significant health risk from chemical
contamination at the site (ATSDR, 2006). Although fish advisories
have been issued for some areas, based on exposure to other indus-
trial contaminants, the most recent Public Health Assessment
could not evaluate risk from exposure to PAHs due to insufficient
fish data. Of 39 species of resident fish in this area, eight constitute
the most likely to be caught and consumed by local sport and sub-
sistence fishers, including walleye, black crappie, white crappie,
smallmouth bass, pikeminnow, yellow bullhead, carp and large-
scale sucker. Clams and crayfish are also commonly harvested for
consumption. Details about resident fish as well as fish consump-
tion data for different population groups is available in the Port-
land Harbor Public Health Assessment (ATSDR, 2006).
The purpose of this study is to apply PSD data in a Public Health
Assessment to demonstrate that PSDs can be used as a biological
surrogate to elucidate spatial and temporal variations in potential
human health risks. To achieve this, the PSD mass concentrations
of PAHs were substituted for fish tissue contaminant concentra-
tions. The spatial and temporal distribution of PSD measured
PAH concentrations were applied to cancer and non-cancer human
health risk assessment models.
2. Methods
2.1. Study area
The study area was the lower 18.5 miles of the Willamette Riv-
er, up to its confluence with the Columbia River. Samplers were
placed at 13 sites on west (W) and east (E) sides of the river chan-
nel from 2004 to 2006 (Fig. 1). The sites were located upriver (RMs
18.5E, 17E, 15.5E, 13W, and 12E), downriver (RM 1E) and within
the Portland Harbor Superfund megasite (RMs 3.5E, 3.5W, 5W,
6.5W, 7W, 7E and 8E). Residential and commercial uses dominate
the upriver area whereas the Superfund megasite area is heavily
industrialized and contains PAH point sources including creosote
and coal tar contaminated sites at RMs 7E and 6.3W respectively.
In addition, urban runoff and combined sewer overflows affect
the area. Undeveloped or agricultural areas predominate down-
river from the harbor.
The study period overlapped with remediation activities that
were carried out at RM 6.3 from August to October, 2005. During
this time submerged tar from a manufactured gas plant (MGP) site
was removed by dredging and a cap was placed over the contam-
inated sediment. The temporal effects of this remediation activity
are analyzed separately from the seasonal data and serve to high-
light the importance of having specific spatial and temporal data
for effective risk assessment in areas affected by sporadic peaks
in contaminant inputs.
2.2. Chemicals and solvents
PAH standards (purities P99%) were obtained from ChemSer-
vice, Inc. (West Chester, PA, USA) and Pesticide or Optima
Ò
grade
cleanup and extraction solvents from Fisher Scientific (Fairlawn,
NJ, USA) were used. The 16 target analytes, which correspond to
the USEPA 16 priority PAHs, included naphthalene, acenaphthene,
acenaphthylene, fluorene, anthracene, phenanthrene, fluoranth-
ene, pyrene, chrysene, benz(a)anthracene, benzo(b)fluoranthene,
benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a,h)anthracene
benzo(ghi)perylene, and indeno(1,2,3-c,d)pyrene.
2.3. Sample collection, extraction and analysis
LFT passive samplers were constructed and fortified with per-
formance reference compounds (PRCs) using methods described
in Sower and Anderson (2008) Briefly, additive-free, 2.7 cm wide,
low-density polyethylene membrane (Barefoot) from Brentwood
Plastic, Inc. (St. Louis, MO, USA) was cleaned with hexanes, cut into
100 cm strips, fortified with dibenz(ah)anthracene as a PRC and
heat sealed at both ends.
From 2004 to 2006 samplers were deployed in multiple 21-d
events during July or August (‘‘dry season’’) and October or Novem-
ber (‘‘wet season’’). This period represents the transition from the
lowest precipitation and river flows of the year to relatively high
precipitation and flows. In 2006 two sampling events were added
from May through June, the transition from high to low flow. Stain-
less steel cages were loaded with five LFTs and suspended 3 m
above the river bottom at each site with an anchor–cage–float sys-
tem described elsewhere (Sethajintanin and Anderson, 2006).
A YSI
Ò
sonde was used during sampler deployment and retrie-
val to collect water chemistry data including temperature, pH, spe-
cific conductivity, and oxidative-reductive potential (ORP). LFT
2 S.E. Allan et al. / Chemosphere xxx (2011) xxx–xxx
Please cite this article in press as: Allan, S.E., et al. Estimating risk at a Superfund site using passive sampling devices as biological surrogates in human
health risk models. Chemosphere (2011), doi:10.1016/j.chemospher e.2011.06.051
Page 2
field cleanup and laboratory extraction were carried out as de-
scribed in Sower and Anderson (2008). Field quality control con-
sisted of duplicate samplers at RMs 7W and 8E, field blanks, trip
blanks and field cleanup blanks. Laboratory quality control in-
cluded reagent blanks, high and low concentration fortifications,
and unexposed fortified LFTs.
After extraction, samples were analyzed by HPLC with diode-ar-
ray (DAD) and fluorescence (FLD) detectors. DAD signals were 230
and 254 nm and FLD excitation and emissions were 230 and 332,
405, 460, respectively. Flow was 2.0 mL min
1
beginning with
40/60% acetonitrile and water and steadily ramping to 100% aceto-
nitrile over a 28 min run per column maker recommendations.
2.4. Exposure, cancer, non-cancer and ecological risk modeling
Water concentrations were calculated using equations pro-
vided in Huckins et al. (2006). PSD concentrations for risk mod-
els are based on the mass of contaminant collected vs. the mass
of the sampler. This mass:mass concentration treats the PSD as a
direct biological surrogate and represents the amount of contam-
inant an organism would take up through passive partitioning.
PAHs do not biomagnify in fin fish and chemical uptake from
water and/or pore water has been described as the most likely
dominant route of uptake for fish and shellfish (Connell, 1990;
Huckins et al., 2006). LFT concentrations best reflect exposure
of organisms residing in the water column; benthic fauna and
infauna may be exposed to different sediment and/or pore water
PAH concentrations.
Exposures and human health endpoints were calculated by
substituting the PSD mass concentrations for the fish tissue con-
taminant concentrations in models previously used for the Port-
land Harbor Public Health Assessment (ATSDR, 2006).
The PSD mass concentrations of PAHs that are recognized as
carcinogenic by the USEPA (benzo(a)anthracene, chrysene,
benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, in-
deno(1,2,3,-c,d)pyrene, and dibenzo(a,h)anthracene) were used
for cancer risk modeling. The PSD mass concentrations of PAHs
that are not recognized as carcinogens were used in the non-cancer
endpoint risk model. The other equation variables and default val-
ues in both the cancer and non-cancer risk models are the same as
those used in the Portland Harbor Public Health Assessment (ATS-
DR, 2006)(Table S1).
Exposure (
l
gkg
1
d
1
) was calculated using Eq. (1) where C is
the mass concentration (PSD substituted for fish), CF is a conver-
sion factor, EF and ED are exposure frequency and duration, respec-
tively, BW is body weight and AT is the averaging time (Table S1).
Exposure ¼
C CF IR EF ED
BW AT
ð1Þ
RM 1E
RM 3.5E
RM 3.5W
RM 5W
RM 6.5W
RM 7E
RM 7W
RM 8E
RM 12E
RM 13W
RM 15.5E
RM 17E
RM 18.5E
Sampling Site
Superfund Megasite
Willamette
River Basin
N
Fig. 1. Sampling sites on the lower Willamette River 2004–2006. Each site is designated by a yellow circle. Not all sites were used every deployment. The red line indicates
the approximate boundaries of the Portland Harbor Superfund megasite.
S.E. Allan et al. / Chemosphere xxx (2011) xxx–xxx
3
Please cite this article in press as: Allan, S.E., et al. Estimating risk at a Superfund site using passive sampling devices as biological surrogates in human
health risk models. Chemosphere (2011), doi:10.1016/j.chemosphere.2011.06.051
Page 3
The ingestion rates (IR) are the 90th (17.5 g d
1
) and 99th per-
centiles (142.4 g d
1
) for fish consumption that were used in the
Portland Harbor Public Health Assessment (ATSDR, 2006) that
evaluated local sport and subsistence angling populations. These
rates may not apply to other situations. In order to assess potential
public health implications of exposure, estimates of exposure can
be compared to estimates of a dose that is likely to be without
appreciable risk of deleterious effects, such as minimal risk level
(MRLs) or reference doses (RfD) (ATSDR, 2006).
Excess cancer risk was determined by normalizing the slope
factors for carcinogenic PAHs to benzo(a)pyrene and then multi-
plying by the sum contaminant exposure (Eq. (2)). Unacceptable
cancer risk, as a matter of policy, was set at an excess of one in
one million (1 10
6
).
Excess cancer risk ¼ Exposure slope factor ð2Þ
For the non-cancer endpoint each contaminant’s exposure was
divided by a chronic RfD or MRL to determine a hazard quotient
(HQ) for the chemical (Eq. (3)). The sum of the HQs for the individ-
ual chemicals yields the hazard index (HI) and, as a matter of pol-
icy, a HI exceeding one represents an unacceptable risk.
Hazard quotient ¼
Exposure
Rfd or MRL
ð3Þ
Analysis of exposure data was carried out using S-plus
Ò
(8.0,
Insightful Corp.); Wilcoxon rank sum tests were used for seasonal
comparisons and Kruskal–Wallis was used for analysis of spatial
differences in exposure, followed by multiple comparisons using
the Tukey 95% simultaneous confidence intervals method. Spatial
and temporal differences in cancer risk were analyzed using
Mann-Whitney rank sum tests in SigmaStat
Ò
. SigmaPlot
Ò
was used
for graphing.
3. Results
A total of 110 samples, from 3 years and 10 different sampling
events are included in this study: six dry (summer) and four wet
season (fall and spring) events, defined by river flow. The wet sea-
son is defined as flow greater than 300 m
3
s
1
; median flows were
higher during the wet season (494 m
3
s
1
) than during the dry sea-
son (246 m
3
s
1
, p < 0.001). Results for water chemistry parameters
support the seasonal delineation; the dry season had higher tem-
perature (22 vs. 16 °C), higher specific conductivity (0.1 vs.
0.08 mS cm
1
), lower ORP (139 vs. 196 mV; all n = 17, p < 0.05),
but no difference in pH (7.4, p = 0.9).
Relative standard deviation (RSD) for the PAH concentrations at
duplicate sites averaged 19%. Target compounds in blanks were
either non-detect or below levels of quantitation. Results are
recovery corrected. Recoveries from method spikes range from an
average 43% for NAP, the lowest molecular weight and most vola-
tile PAH, to 108% for IPY, with an overall average of 77%.
A detailed analysis of spatial and temporal variations of water
concentrations of PAHs in the lower Willamette River can be found
in Sower and Anderson (2008). Briefly, the sum concentration of 16
PAH analytes (
P
16
PAH) in the Superfund area (11.4 ng L
1
) is sig-
nificantly higher than upriver sites (3.1 ng L
1
, p < 0.001), but not
downriver sites. The upriver area does not exhibit significant vari-
ation among sites, but Superfund sites do. RMs 7W, 6.5W and 5W
are consistently the most contaminated sites. None of the average
concentrations for any site exceed the EPA human health Water
Quality Criteria for consumption of water (3.8 ng L
1
)or
‘water + organism’ (18 ng L
1
)(US EPA, 1999) for the total carcino-
genic PAHs, though some sites exceeded the threshold seasonally
or during specific sampling events.
3.1. Comparison of PSD and fish tissue concentration data
While it is widely understood that humans do not consume pas-
sive samplers, comparisons of PAH concentrations in PSDs and fish
tissue from the Portland Harbor Superfund site demonstrate that
using PSD concentrations in a Public Health Assessment would
provide a reasonable and conservative estimate of exposure that
would be protective of human health without significantly overes-
timating risk. Table 1 presents fish tissue data from the Lower Wil-
lamette Group (Integral et al., 2009), some of which was used in
the Portland Harbor Public Health Assessment (ATSDR, 2006)as
well as PSD data from this study. The fish and shellfish were col-
lected from Portland Harbor during a period that overlapped with
the PSD study; however these two studies are unrelated to one an-
other. Furthermore, it is important to highlight that PAHs were not
included in the Portland Harbor Public Health Assessment because
of insufficient data (ATSDR, 2006); therefore, the data presented in
Table 1 is based on a limited sample set. The side-by-side compar-
ison demonstrates that PSDs from this study captured the magni-
tude, range and variability of PAH concentrations that have been
reported in a variety of fish and shellfish tissues from the harbor
and provide an estimate of exposure that is realistic and protective.
3.2. Spatial and temporal variations in PAH exposure
As detailed in Section 2, exposure to PAHs from consumption of
fish is dependent on a number of factors; some of which have stan-
dard values in risk assessment models, and others that are deter-
mined for specific human populations, such as consumption rates
of organisms. In this study, the mass:mass concentrations of PAHs
in LFT passive samplers are substituted for fish tissue concentra-
tions in the exposure formula. Exposure is therefore a factor of con-
sumption rate on the measured PSD concentrations.
To avoid confounding the interpretation of spatial differences in
exposure to PAHs, data that were acquired during the tar removal
dredging in the Superfund have been removed from these analyses.
The effects of remediation activities on exposure and risk are dis-
cussed later in the results.
Significant differences in PSD concentrations of the
P
16
PAH
were observed within and outside of the Superfund megasite
(p < 0.001). A median
P
16
PAH concentration of 603
l
gkg
1
in
the Superfund was significantly greater than 431
l
gkg
1
at upri-
ver sites (p < 0.001) but not greater than the downriver area. Sim-
ilarly, significant differences in carcinogenic PAHs were observed
(p < 0.001), where median exposure was greater within the Super-
fund (12.1
l
gkg
1
) than upriver (5.7
l
gkg
1
) but not downriver.
A more detailed analysis of PSD concentrations shows signifi-
cant differences between sites, both within and outside of the
Superfund megasite for
P
16
PAH and carcinogenic PAHs
(p = 0.002 and p < 0.001 respectively). Exposure to
P
16
PAH is
greater at RM 7W and 3.5W (1110 and 1150
l
gkg
1
medians
respectively) than three upriver sites, which had median concen-
trations between 353 and 466
l
gkg
1
. A similarly high median
concentration of
P
16
PAH was observed in PSD extracts from RM
6.5W (1270
l
gkg
1
); however this site was not differentiated
from other sites in the analysis, likely due to a smaller sample size.
Furthermore, the PSD concentration at RM 7W was significantly
greater than at RM 8E (448
l
gkg
1
median), though both sites
are located within a mile of each other in the Superfund megasite
(Fig. 2).
Median PSD concentrations of carcinogenic PAHs were greater
at RM 3.5W (22.3
l
gkg
1
) than RMs 18.5E, 17E and 12E (4.2, 5.5
and 6.4
l
gkg
1
respectively). Additionally, it was greater than at
RM 8E (10.1
l
gkg
1
), which is also located in the Superfund
megasite. Interestingly, RM 7W did not differentiate itself from
other sites with regards to carcinogenic PAHs, although it had
4 S.E. Allan et al. / Chemosphere xxx (2011) xxx–xxx
Please cite this article in press as: Allan, S.E., et al. Estimating risk at a Superfund site using passive sampling devices as biological surrogates in human
health risk models. Chemosphere (2011), doi:10.1016/j.chemospher e.2011.06.051
Page 4
significantly higher levels of total PAHs than sites located both
within and outside of the Superfund area (Fig. 2).
No differences in exposure to total or carcinogenic PAHs were
observed between the wet and dry seasons at the upriver or down-
river sites. In contrast, significant differences were observed be-
tween the wet and dry season for both carcinogenic and total
PAHs within the Superfund megasite (p < 0.001). PSD concentra-
tions of PAHs in the Superfund megasite were greater during the
dry than the wet season (1470 and 442
l
gkg
1
respectively). Sim-
ilarly, median concentrations of carcinogenic PAHs were
33.5
l
gkg
1
in the dry season compared to 8.5
l
gkg
1
in the
wet season.
3.3. Spatial and temporal variations in cancer and non-cancer risk
All areas exceed the established threshold of one excess cancer
risk in 1 000 000 (1 10
6
). Estimated risk of cancer in excess of
the background rate for the Superfund megasite and downriver
(1.3 10
5
and 1.7 10
5
, respectively, for average consumption)
were significantly higher than upriver sites (4.5 10
6
, p < 0.001)
(Fig. 3). Within the Superfund megasite, estimated excess risk
was up to five times greater at RM 7E than 7W; sites located on
opposite banks and separated by only a few hundred meters (Ta-
ble 2). These estimated numbers of cancer cases in excess of the
background are based on the assumption, from the risk assessment
model applied here, that all individuals are equally exposed.
Non-cancer risk from PAHs was also higher at Superfund and
downriver sites than urban areas (p < 0.001) with RMs 7W, 6.5W,
and 3.5W exhibiting the highest hazard quotients, though all were
below one by more than two orders of magnitude (Table 2).
The increased PAH concentrations in the Superfund area during
the dry season result in significantly elevated risk (Fig. 3). Both
non-cancer HQs and excess cancers increased during the dry peri-
od (p = 0.004 and p < 0.001 respectively), however the non-cancer
HQs remained below unacceptable risk levels (Table 2). The cancer
model predicts four times greater cancer risk from fish consump-
tion in the Superfund area during the dry season compared to
wet season. Notably, the excess cancer risk at RM 7W from average
consumption of PSD measured mass concentrations increases by
sevenfold during the dry season from 7.8 10
6
to 6.0 10
5
(n = 18, p = 0.005).
3.4. Effects of remediation activities on risk
Dredging of a coal tar contaminated site at RM 6.3W removed
more than 11 500 m
3
of submerged tar contamination from August
Table 1
Concentrations of PAHs in PSDs and fish and shellfish tissue from the Portland Harbor Superfund site.
Chemical Concentration (
l
gkg
1
) average (maximum)
PSD
a
Fish and shellfish from Portland Harbor Superfund
b
Superfund Upstream Smallmouth bass Carp Sculpin Crayfish Clam
Naphthalene 1.0 (6.5) 0.7 (3.8) 10 (86) 20 (56) 19 (250) 0.82 (2.9) 25 (78)
Acenaphthene 5.5 (54) 0.02 (1.1) 13.7 (95)
c
34.1 (75)
c
NA NA NA
Fluorene 13 (84) 5.4 (70) 9.31 (69)
c
22.3 (53)
c
NA NA NA
Phenanthrene 44 (219) 4.9 (24) 20 (85) 10 (16) 6.8 (33) 52 (97) 35 (300)
Fluoranthene 170 (850) 24 (57) 2.77 (36)
c
NA NA 10.2 (130)
c
NA
Benz(a)anthracene 51 (504) 10 (44.6) NA NA NA 2.01 (80)
c
NA
Chrysene 36 (172) 10 (28) 20 (85) NA NA 2.16 (87)
c
NA
Pyrene 170 (733) 35 (92) 2.9 (39)
c
NA NA 4.02 (83) NA
Benzo(a)pyrene 14 (70) 4.1 (21) 0.64 (1.3) NA NA 1.1 (7.5) 34 (490)
P
16
PAH 819 (3094) 397 (1147) 71.5 (308) 85.5 (222) 52.3 (550) 71.2 (477) 478 (4980)
P
carcinogenic PAH 23 (123) 7.6 (25.2) 2.5 (6.8) 2.1 (2.8) 3.18 (9.8) 22 (170) 220 (2700)
NA indicates that data was not available for this publication.
Notes: PSD average and maximum concentrations are based on measurements made during the study period; data obtained in the superfund during tar removal remediation
were not included. Concentrations in organisms correspond to reported whole body measurements in fish and shellfish obtained from the Portland Harbor Superfund site in
an unrelated study. Not all analytes used to compute reported totals were available to be shown in this table.
a
PSD measured concentrations of PAH analytes (this study).
b
Data from the Lower Willamette Group Portland Harbor RI/FS (Integral et al., 2009) except where noted (c).
c
Data from Portland Harbor Public Health Assessment (ATSDR, 2006).
0
500
1000
1500
2000
2500
3000
3500
Dry Season
Wet Season
Tar Removal
River Mile
1E
3.5W
3.5E
6.5W
7W
7E
8E
12E
13W
15.5E
17E
18.5E
0
50
100
150
200
Downriver
Superfund Upriver
Fig. 2.
P
16
PAH and carcinogenic PAHs in PSDs. Mass-to-mass concentration of sum
PAHs and sum carcinogenic PAHs in passive sampling devices (PSDs) at sites
downriver, upriver and within the Portland Harbor Superfund megasite. Each point
represents one observation during the dry season (closed circles), wet season (open
circles) or tar removal remediation (triangles). These values were used in place of
fish tissue concentrations to calculate exposure for risk assessment models.
S.E. Allan et al. / Chemosphere xxx (2011) xxx–xxx
5
Please cite this article in press as: Allan, S.E., et al. Estimating risk at a Superfund site using passive sampling devices as biological surrogates in human
health risk models. Chemosphere (2011), doi:10.1016/j.chemosphere.2011.06.051
Page 5
to October 2005. LFT samplers downriver at RM 3.5W and upriver
at RM 7W during this period accumulated significantly elevated
P
16
PAH and carcinogenic PAH concentrations (Fig. 2). September
2005 samples, taken during the middle of the dredging activity,
from RM 7W down to RM 1 are the highest concentrations of
P
16
PAH and carcinogenic PAHs recorded during this study
(Fig. 2). The median
P
16
PAH and carcinogenic PAH pre- and
post-tar removal are significantly lower than the tar removal med-
ian. The highest observed carcinogenic PAH concentrations in
water measured during this study occurred at RMs 7W and 5W
in September 2005 (71 ng L
1
and 20 ng L
1
, respectively). At RM
3.5W, chrysene and benz(a)anthracene exceed the US EPA Water
Quality Criteria limit of 3.8 ng L
1
for the consumption of water
and organism, while at RM 7W benzo(b)fluoranthene and ben-
zo(a)pyrene exceeded this limit and chrysene and benz(a)anthra-
cene exceeded the 18 ng L
1
limit for the consumption of
organisms.
4. Discussion
PSDs are well established for determining the water concentra-
tions of freely dissolved and thus bioavailable, organic contami-
nants (Huckins et al., 2006; Adams et al., 2007; Anderson et al.,
2008). Their use for risk assessment is less well established, how-
ever, they respond to the need for biologically relevant exposure
data (Birnbaum, 2010) and they can be standardized across stud-
ies. Furthermore, initial comparisons of PAH concentrations in
PSDs and fish tissue demonstrate that PSDs capture the magnitude
and variability of PAH exposure, and thus are an adequate surro-
gate for this parameter in some risk models. Obtaining PSD data
from sites within and outside of the Superfund area provided a
more representative range of concentrations for highly mobile fish
species that are likely to move through large areas of the river and
might avoid contaminated areas. Conversely, less motile or sessile
organisms, such as crayfish and clams from the Superfund area had
concentrations of PAHs in their tissues more closely aligned with
PSD data from the Superfund area. Fin fish, unlike PSDs, ingest
and metabolize PAHs, however passive partitioning has been
shown to be the principal route of uptake (Connell, 1990) and
the results of this study concord with other publications that dem-
onstrate the comparability of PSDs (SPMDs) with finfish and bi-
valves (Huckins et al., 2006). As mentioned by other researchers
(Baussant et al., 2001; Ke et al., 2007) a comparison of this study
to fish tissue data from the area (Table 1) demonstrated higher
concentrations of low molecular weight PAHs in fin fish than PSDs.
This observation merits further study; however, due to these com-
pounds classification as non-carcinogenic and their relatively high
MRLs, the lower concentrations observed in PSDs do not have a sig-
nificant effect on the outcomes of a Public Health Assessment
based on the PSD data.
Using PSDs as direct biological surrogates by measuring unme-
tabolized parent compounds through mass:mass concentrations
reveals a more complete exposure potential. In Portland Harbor,
the large number of PSD samples over several seasons and years,
provided a much more complete understanding of risk for the area,
with specific spatial and temporal resolution that proved to be sig-
nificant. Notably, risk from exposure to PAHs from consumption of
fish had not been evaluated in the Public Health Assessment for
Portland Harbor due to insufficient fish data. Using PSDs in place
of organisms eliminates problems associated with capturing
Table 2
Cancer and non-cancer risk associated with consumption of fish estimated by PSD
a
,
b
.
River location and season N Non-cancer hazard quotient consumption Excess cancer risk consumption
Average High p-Value Average High p-Value
Upriver 37
Wet 13 2.0 10
4
1.3 10
3
3.8 10
6
3.1 10
5
Dry 24 4.0 10
4
3.3 10
3
0.07 5.6 10
6
4.6 10
5
0.31
Superfund megasite 64
Wet 28 9.3 10
4
7.6 10
3
6.7 10
6
5.4 10
5
Dry 36 3.3 10
3
2.7 10
2
0.004 2.6 10
5
2.1 10
4
<0.001
Superfund no tar events 45
Wet 22 3.6 10
4
3.0 10
3
6.5 10
6
5.3 10
5
Dry 23 2.9 10
3
2.4 10
2
<0.001 2.2 10
5
1.8 10
4
<0.001
RMs 7W and 5W 28
No tar 19 1.1 10
3
8.5 10
3
1.5 10
5
1.2 10
4
Tar 9 4.5 10
3
3.7 10
2
0.02 9.1 10
5
7.4 10
4
<0.001
Downriver 10
Wet 4 3.4 10
4
1.5 10
2
9.1 10
6
7.4 10
5
Dry 6 1.9 10
3
2.8 10
3
0.11 1.8 10
5
1.5 10
4
0.18
Threshold = 1 Threshold = 1.0 10
6
All test are at
a
= 0.05.
a
Mann–Whitney rank sum tests within location between seasons.
b
p-Values are for comparisons between seasons.
Downriver Superfund Upriver
Number of Excess Cancers
(per 1,000,000 individuals)
0
50
100
150
200
Wet Season
Dry Season
Tar Removal
Fig. 3. Estimated number of cancers, in excess of the background rate, per
1 000 000 individuals exposed to carcinogenic PAHs. Calculations are based on
average fish consumption rates; where PSD concentrations have been substituted
for fish tissue concentrations. Data from all sites located in each area of the river
(upriver, downriver and within the Superfund) were averaged for the wet and dry
seasons and observations associated with tar removal remediation activities are
presented separately. Error bars represent 95% confidence intervals, based on
variability in the PSD measured concentrations for each site-season, and only one
observation was made at the downriver site during tar removal. See Table 2 for
statistical analyses of these data.
6 S.E. Allan et al. / Chemosphere xxx (2011) xxx–xxx
Please cite this article in press as: Allan, S.E., et al. Estimating risk at a Superfund site using passive sampling devices as biological surrogates in human
health risk models. Chemosphere (2011), doi:10.1016/j.chemospher e.2011.06.051
Page 6
samples, destructive sampling and analyzing compounds in an
analytically complex biological matrix.
Temporal disparities in exposure and estimated risk were ob-
served in the Superfund area. Several studies have observed higher
PAH concentrations with increasing precipitation, flows, and urban
runoff (Ko and Baker, 2004; Gasperi et al., 2005; Brown and Peake,
2006) and Stout et al. (2004) note that storm water is the greatest
contributor to sediment PAHs over time. However, our data dem-
onstrate an opposite tendency, where the dry season is associated
with higher water concentrations, higher exposure, and conse-
quently higher risk, in the Superfund area. Dilution does not ex-
plain the concentration and risk disparities between wet and dry
seasons in the Superfund area either. Unlike the Superfund sites,
upriver and downriver areas do not demonstrate seasonal varia-
tions. If the observed differences in the Superfund were due to
dilution, this should be a uniform effect in the river. One potential
explanation for the seasonal differences observed only within the
Superfund site, and especially at 7W, 6.5W and 3.5W, is that con-
taminant diffusion from sediments into overlying water is respon-
sible for high concentrations. The contamination may be from
riverbank sediments and higher wet season flows could inhibit
groundwater movement into the river due to hydraulic pressure
and bank storage (Winter et al., 1998; Sower and Anderson,
2008). Another possible explanation is that higher summer tem-
peratures cause greater contaminant diffusion from the sediment
to the water column. Further investigation is required to elucidate
sources of seasonal disparities in PAH contamination in the Super-
fund area.
A sediment cap over creosote contaminated sediments at RM
7E, installed prior to this study, was found to be effective in pre-
venting PAH contamination into the overlying water column
(Sower and Anderson, 2008) but did not diminish RM 7W high con-
centrations. The cause of the significant difference observed be-
tween sites located in close proximity to one another, such as
RMs 7E, 7W and 8E, merits further study. It also highlights the
importance of considering spatial differences in risk on a small
scale, which can be achieved by taking PSD data into account in
risk assessments.
While remediation of contaminated sites is desirable, few stud-
ies have assessed the potential impacts of dredging on exposure
and risk during and after remediation (Committee on Sediment
Dredging at Superfund Megasites, 2007). This study provided an
opportunity to evaluate the effects of dredging on PAH bioavail-
ability and potential human health risks from exposure. Prior to
capping, dredging at RM 6.3W removed significant quantities
(>11 500 m
3
) of coal tar; however the area remains a higher risk
with higher freely-dissolved PAH concentrations than surrounding
areas, particularly in the dry season.
This study demonstrates an association between variable flows,
sediment disturbance and freely-dissolved and, thus, bioavailable
contamination in the water column. Although the dredging pro-
duced a spike in exposure to PAHs, and a corresponding increase
in risk values, the duration of the effect was limited to the time
that it took to complete the operation. The short duration of the
disturbance would only be expected to have an immediate and
more substantial effect on aquatic organisms. Though fish kills
were observed within the containment area, none were observed
outside the barriers (Parametrix, 2006).
The site downriver from the Superfund megasite, RM 1E, is not
significantly different in concentration from the Superfund sites.
While the Portland Harbor Public Health Assessment only sampled
within the Portland Harbor Superfund sites, our data demonstrate
that the downriver site has similar concentrations and could pose
similar health risks. Seasonal and spatial information like this
could be useful to public health officials when constructing a
health assessment or determining where to post warning signs.
5. Conclusions
PSDs provide spatially and temporally resolved contaminant
exposure information that, as demonstrated here, can be incorpo-
rated into risk assessment models. This study revealed significant
spatial and temporal differences in risk that would not have been
elucidated in a traditional risk assessment, such as the Portland
Harbor Public Health Assessment. Although it is clear that humans
do not consume PSDs, their application as a biological surrogate in
risk assessment models has the potential to provide specific spatial
and temporal contaminant exposure information that can assist
public health professionals in accurately evaluating human health
risks. Furthermore, using PSDs for risk assessment has the advan-
tages of larger sample size, non-destructive sampling and compa-
rability across studies. PSDs provide biologically relevant
exposure data for risk assessment that could be used when organ-
ism data is not available or to complement, and further refine,
other measures of exposure.
Acknowledgements
This project was supported in part by award numbers P42
ES01645 and P42 ES00210 from the National Institute of Environ-
mental Health Sciences. Further funding was provided by the
SETAC Chemistry Early Career for Applied Ecological Research
Award sponsored by the American Chemistry Council to K.A.A
and MFGSC Grant E3003850. The content is solely the responsibil-
ity of the authors and does not necessarily represent the official
views of the funding agencies. We appreciate assistance from R.
Grove of USGS, Corvallis, OR, and D. Sethajintanin, E. Johnson, W.
Hillwalker, L. Quarles, K. Hobbie and A. Perez from OSU.
Appendix A. Supplementary material
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.chemosphere.2011.06.051.
References
Adams, R.G., Lohmann, R., Fernandez, L.A., Macfarlane, J.K., Gschwend, P.M., 2007.
Polyethylene devices: passive samplers for measuring dissolved hydrophobic
organic compounds in aquatic environments. Environ. Sci. Technol. 41, 1317–
1323.
Allan, I.J., Booij, K., Paschke, A., Vrana, B., Mills, G.A., Greenwood, R., 2009. Field
performance of seven passive sampling devices for monitoring of hydrophobic
substances. Environ. Sci. Technol. 43, 5383–5390.
Anderson, K.A., Sethajintanin, D., Sower, G., Quarles, L., 2008. Field trial and
modeling of uptake rates of in situ lipid-free polyethylene membrane passive
sampler. Environ. Sci. Technol. 42, 4486–4493.
ATSDR, 2005. Public Health Assessment Guidance Manual (2005 Update). ATSDR,
Atlanta, GA. <http://www.atsdr.cdc.gov/hac/PHAManual>.
ATSDR, 2006. Public Health Assessment: Portland Harbor, Multnomah County,
Oregon, EPA Facility ID: OR0001297969. Oregon Department of Human Services
Superfund Health Investigation and Education Program, US Department of
Health and Human Services, Agency for Toxic Substances and Disease Registry,
Atlanta, GA.
Baussant, T., Sanni, S., Jonsson, G., Skadsheim, A., Borseth, J.F., 2001.
Bioaccumulation of polycyclic aromatic compounds: 1. Bioconcentration in
two marine species and in semipermeable membrane devices during chronic
exposure to dispersed crude oil. Environ. Toxicol. Chem. 20, 1175–1184.
Birnbaum, L.S., 2010. Applying research to public health questions: biologically
relevant exposures. Environ. Health Perspect. 118.
Boehm, P.D., Page, D.S., Brown, J.S., Neff, J.M., Bence, A.E., 2005. Comparison of
mussels and semi-permeable membrane devices as intertidal monitors of
polycyclic aromatic hydrocarbons at oil spill sites. Mar. Pollut. Bull. 50, 740–
750.
Brown, J.N., Peake, B.M., 2006. Sources of heavy metals and polycyclic aromatic
hydrocarbons in urban stormwater runoff. Sci. Total Environ. 359, 145–155.
Committee on Sediment Dredging at Superfund Megasites, N.R.C., 2007. Sediment
Dredging at Superfund Megasites: Assessing the Effectiveness. National
Academies Press, Washington, DC.
Connell, D.W., 1990. Bioaccumulation of Xenobiotic Compounds. CRC Press Inc.,
Boca Raton, FL.
S.E. Allan et al. / Chemosphere xxx (2011) xxx–xxx
7
Please cite this article in press as: Allan, S.E., et al. Estimating risk at a Superfund site using passive sampling devices as biological surrogates in human
health risk models. Chemosphere (2011), doi:10.1016/j.chemosphere.2011.06.051
Page 7
Gasperi, J., Rocher, V., Moilleron, R.G., Chebbo, G., 2005. Hydrocarbon loads
from street cleaning practices: comparison with dry and wet weather flows
in a Parisian combined sewer system. Polycyclic Aromat. Compd. 25, 169–
181.
Huckins, J.N., Petty, J.D., Booij, K., 2006. Monitors of Organic Chemicals in the
Environment: Semipermeable Membrane Devices. Springer, New York.
Integral, Windward, Kennedy/Jenks, Anchor-QEA, 2009. Portland Harbor RI/FS
Remedial Investigation Report IC09-0003. Prepared for the Lower Willamette
Group, Portland OR by Integral Consulting Inc., Portland, OR; Windward
Environmental LLC, Inc., Seattle, WA; Kennedy/Jenks Consultants, Portland,
OR; and Anchor QEA LLC, Seattle, WA, Portland Oregon.
Ke, R.H., Xu, Y.P., Huang, S.B., Wang, Z.J., Huckins, J.N., 2007. Comparison of the
uptake of polycyclic aromatic hydrocarbons and organochlorine pesticides by
semipermeable membrane devices and caged fish (Carassius carassius) in Taihu
Lake, China. Environ. Toxicol. Chem. 26, 1258–1264.
Ko, F.C., Baker, J.E., 2004. Seasonal and annual loads of hydrophobic organic
contaminants from the Susquehanna River basin to the Chesapeake Bay. Mar.
Pollut. Bull. 48, 840–851.
Linkov, I., Burmistrov, D., Cura, J., Bridges, T.S., 2002. Risk-based management of
contaminated sediments: consideration of spatial and temporal patterns in
exposure modeling. Environ. Sci. Technol. 36, 238–246.
Parametrix, 2006. GASCO Early Removal Action Construction Oversight Report.
Portland, Oregon.
Peven, C.S., Uhler, A.D., Querzoli, F.J., 1996. Caged mussels and semipermeable
membrane devices as indicators of organic contaminant uptake in Dorchester
and Duxbury Bays, Massachusetts. Environ. Toxicol. Chem. 15, 144–149.
Sethajintanin, D., Anderson, K.A., 2006. Temporal bioavailability of organochlorine
pesticides and PCBs. Environ. Sci. Technol. 40, 3689–3695.
Sower, G.J., Anderson, K.A., 2008. Spatial and temporal variation of freely dissolved
polycyclic aromatic hydrocarbons in an urban river undergoing superfund
remediation. Environ. Sci. Technol. 42, 9065–9071.
Stout, S.A., Uhler, A.D., Emsbo-Mattingly, S.D., 2004. Comparative evaluation of
background anthropogenic hydrocarbons in surficial sediments from nine
urban waterways. Environ. Sci. Technol. 38, 2987–2994.
Tao, Y., Zhang, S., Wang, Z., Christie, P., 2008. Predicting bioavailability of PAHs in
soils to wheat roots with triolein-embedded cellulose acetate membranes and
comparison with chemical extraction. J. Agric. Food. Chem. 56, 10817–10823.
US EPA, 1999. National Recommended Water Quality Criteria-Correction. National
Center for Environmental Publications and Information, Office of Water, United
States Environmental Protection Agency, Cincinnati, OH.
Verweij, F., Booij, K., Satumalay, K., van der Molen, N., van der Oost, R., 2004.
Assessment of bioavailable PAH, PCB and OCP concentrations in water, using
semipermeable membrane devices (SPMDs), sediments and caged carp.
Chemosphere 54, 1675–1689.
Winter, T.C., Harvey, J.W., Franke, O.L., Alley, W.M., 1998. Ground Water and Surface
Water: A Single Resource. United States Geological Survey, Denver, CO.
8 S.E. Allan et al. / Chemosphere xxx (2011) xxx–xxx
Please cite this article in press as: Allan, S.E., et al. Estimating risk at a Superfund site using passive sampling devices as biological surrogates in human
health risk models. Chemosphere (2011), doi:10.1016/j.chemospher e.2011.06.051
Page 8
  • Source
    • "wastewater markers) and Polycyclic Aromatic Hydrocarbons (PAHs) (Stewart et al., 2015). The blueprint for this study was recent international developments in using PSDs in environmental monitoring (Allan et al., 2011; Alvarez et al., 2014; Perron et al., 2013). "
    Full-text · Technical Report · Mar 2016
  • Source
    • "With regard to MTBE, the American Conference of Governmental Industrial Hygienists (ACGIH) has established an occupational Threshold Limit Value (TLV) of 50 ppm. The present study was designed to conduct cancer and non-cancer risk assessments for inhalation exposure to MTBE in petrol station environments in southern China by using human health risk models [30,31]. "
    [Show abstract] [Hide abstract] ABSTRACT: Methyl tertiary butyl ether (MTBE), a well known gasoline additive, is used in China nationwide to enhance the octane number of gasoline and reduce harmful exhaust emissions, yet little is known regarding the potential health risk associated with occupational exposure to MTBE in petrol stations. In this study, 97 petrol station attendants (PSAs) in southern China were recruited for an assessment of the health risk associated with inhalation exposure to MTBE. The personal exposure levels of MTBE were analyzed by Head Space Solid Phase Microextraction GC/MS, and the demographic characteristics of the PSAs were investigated. Cancer and non-cancer risks were calculated with the methods recommended by the United States Environmental Protection Agency. The results showed that the exposure levels of MTBE in operating workers were much higher than among support staff (p < 0.01) and both were lower than 50 ppm (an occupational threshold limit value). The calculated cancer risks (CRs) at the investigated petrol stations was 0.170 to 0.240 per 106 for operating workers, and 0.026 to 0.049 per 106 for support staff, which are below the typical target range for risk management of 1 × 10−6 to 1 × 10−4; The hazard quotients (HQs) for all subjects were <1. In conclusion, our study indicates that the MTBE exposure of PSAs in southern China is in a low range which does not seem to be a significant health risk.
    Full-text · Article · Feb 2016 · International Journal of Environmental Research and Public Health
  • Source
    • "When these passive samplers are placed in the aquatic environment , they mimic the bioconcentration process of aquatic animals absorbing PAHs from the surrounding area, and concentrations of PAHs in the passive samplers are then integrated over the entire duration of exposure (Huckins et al. 1990). In addition, the passive samplers are effective in measuring time-integrated subnanograms-per-liter levels of PAHs in water (Lohmann and Muir 2010; Allan et al. 2011). "
    [Show abstract] [Hide abstract] ABSTRACT: One year after the Deepwater Horizon oil spill accident, semipermeable membrane devices (SPMDs) and polyethylene devices (PEDs) were deployed in wetland areas and coastal areas of the Gulf of Mexico (GOM) to monitor polycyclic aromatic hydrocarbons (PAHs). The measured PAH levels with the PEDs in coastal areas were 0.05-1.9 ng/L in water and 0.03-9.7 ng/L in sediment porewater. With the SPMDs, the measured PAH levels in wetlands (Barataria Bay) were 1.4-73 ng/L in water and 3.3-107 ng/L in porewater. The total PAH concentrations in the coastal areas were close to the reported baseline PAH concentrations in GOM; however, the total PAH concentrations in the wetland areas were one or two orders of magnitude higher than those reported in the coastal areas. In light of the significant spatial variability of PAHs in the Gulf's environments, baseline information on PAHs should be obtained in specific areas periodically.
    Full-text · Article · Sep 2015 · Environmental Monitoring and Assessment
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