Perfluoroalkyl acids (PFAAs) in indoor and outdoor dusts around a mega fluorochemical industrial park in China: Implications for human exposure
Abstract
The manufacture of fluorochemicals can lead to high levels of perfluoroalkyl acids (PFAAs) contaminating the surrounding environment and consequently elevated exposure to the local residents. In this study, measurements of PFAAs associated with indoor and outdoor dusts around a mega fluorochemical industrial park (FIP) were made. Perfluorooctanoic acid (PFOA) and short-chain perfluoroalkyl carboxylic acids (C4-C7 PFCAs) were the predominant forms in all samples. The signature of the PFAAs in dusts in the local area matched that found within the FIP complex. The contamination plume in the local area could be linked to the prevailing wind direction starting from the FIP. The dust concentrations decreased exponentially with distance from the FIP (noticeably in the first 5km). PFAAs contamination could be detected at the furthest location, 20km away from the FIP. The concentrations of PFAAs were higher in indoor dust (73-13,500ng/g, median: 979ng/g) than those in outdoor dust (5-9495ng/g, median: 62ng/g) at every location. The highest estimated daily intake of PFOA via dust ingestion (26.0ng/kg·bw/day) was for toddlers (2-5years) living 2km away from the FIP, which is posing human health risk, though exposure remains within the provisional tolerable daily intake values.
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Perfluoroalkyl acids (PFAAs) in indoor and outdoor dusts around a mega
fluorochemical industrial park in China: Implications for human exposure
Hongqiao Su
a,b
, Yonglong Lu
a,
⁎,PeiWang
a
,YajuanShi
a
, Qifeng Li
a,b
, Yunqiao Zhou
a,b
, Andrew C. Johnson
c
a
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
b
University of Chinese Academy of Sciences, Beijing 100049, China
c
Centre for Ecology & Hydrology, Maclean Building, Crowmarsh Gifford, Wallingford, Oxon OX10 8BB, UK
abstractarticle info
Article history:
Received 8 April 2016
Received in revised form 1 July 2016
Accepted 1 July 2016
Available online xxxx
The manufacture of fluorochemicals can lead to high levels of perfluoroalkyl acids (PFAAs) contaminating the
surrounding environment and consequently elevated exposure to the local residents. In this study, measure-
ments of PFAAs associated with indoor and outdoor dusts around a mega fluorochemical industrial park (FIP)
were made. Perfluorooctanoic acid (PFOA) and short-chain perfluoroalkyl carboxylic acids (C4–C7 PFCAs)
were the predominant forms in all samples. The signature of the PFAAs in dusts in the local area matched that
found within the FIP complex. The contamination plume in the local area could be linked to the prevailing
wind direction starting from the FIP. The dust concentrations decreased exponentially with distance from the
FIP (noticeably in the first 5 km). PFAAs contamination could be detected at the furthest location, 20 km away
from the FIP. The concentrations of PFAAs were higher in indoor dust (73–13,500 ng/g, median: 979 ng/g)
than those in outdoor dust (5–9495 ng/g, median: 62 ng/g) at every location. The highest estimated daily intake
of PFOA via dust ingestion (26.0 ng/kg·bw/day) was for toddlers (2–5 years) living 2 km away from the FIP,
which is posing human health risk, though exposure remains within the provisional tolerable dailyintake values.
© 2016 Elsevier Ltd. All rights reserved.
Keywords:
PFOA
C4–C7 PFCAs
Indoor dust
Outdoor dust
Mega fluorochemical industrial park
1. Introduction
Perfluoroalkyl acids (PFAAs), including perfluorocarboxylates
(PFCAs) and perfluorosulfonates (PFSAs), are synthesized chemicals
which have high surface activity, thermal and acid resistance, and repel-
lency of water and oil (Giesy and Kannan, 2002).Thesepropertieshave
led to theiruse in various commercial products and industrial processes,
such as textile, food containers, upholstery, fire-fighting foams, metal
plating and fluoropolymer manufacturing (OECD, 2002; Buck et al.,
2011; Wang et al., 2014b). Their presence in so many products and
non-biodegradability has led to their wide distribution in the environ-
ment. With a potential for bioaccumulation and potential adverse ef-
fects in biota and humans, they have attracted increasing scientific
attention and enhanced awareness among regulators (Lindstrom et al.,
2011). In 2009, perfluorooctane sulfonic acid (PFOS), its salts, and
perfluorooctane sulfonyl fluoride (POSF) were listed as persistent or-
ganic pollutants (POPs) by the Stockholm Convention (UNEP, 2009).
Perfluorooctanoic acid (PFOA), another highly investigated PFAA, is
due to be phased out in the USA following agreements with industry
in that country by 2015 (USEPA, 2006). There has been a trend for the
manufacture of PFAAs and fluoro-polymers/-telomers to shift from
North America and Europe to emerging economies, especially China
(Wang et al., 2014a; Wang et al., 2016).
In humans, statistical associations between PFOS or PFOA levels and
reduced birth weight (Stein et al., 2009), cholesterol (Nelson et al.,
2010), uric acid (Steenland et al., 2010), sperm quality (Joensen et al.,
2009), kidney and testicular cancer (Barry et al., 2013), and ulcerative
colitis (Steenland et al., 2013) have been reported. The main routes for
human exposure to PFAAs include ingestion of dust, food and drinking
water consumption, and inhalation of PFAAs-contaminated air
(Fromme et al., 2009; D'Hollander et al., 2010). A number of studies
have reported that household dust contains PFAAs (Björklund et al.,
2009; Goosey and Harrad, 2011; Fraser et al., 2013). Indoor dust is mix-
ture of settled particles, human skin and fabric micro fibers, whereas
outdoor dust is mostly made of microorganisms, spores, traffic-related
emissions and soil-derived particles. Humans can mitigate their expo-
sure to contaminants in food or beverages by choosing different prod-
ucts, but this choice does not exist when the contaminant is present in
their physical environment where they work, live and play. Given the
association of PFAAs with dust, it is likely that young children who are
often in close contact with floors and dusty surfaces and have a greater
propensity to put their hands and objects in their mouths will be partic-
ularly exposed.
Our previous studies havefound an important pointsource of PFAAs,
amegafluorochemical industrial park (FIP), in the Xiaoqing River basin
Environment International xxx (2016) xxx–xxx
⁎Corresponding author.
E-mail address: yllu@rcees.ac.cn (Y. Lu).
EI-03396; No of Pages 7
http://dx.doi.org/10.1016/j.envint.2016.07.002
0160-4120/© 2016 Elsevier Ltd. All rights reserved.
Contents lists available at ScienceDirect
Environment International
journal homepage: www.elsevier.com/locate/envint
Please cite this article as: Su, H., et al., Perfluoroalkyl acids (PFAAs) in indoor and outdoor dusts around a mega fluorochemical industrial park in
China: Implications for h..., Environ Int (2016), http://dx.doi.org/10.1016/j.envint.2016.07.002
in northern China (Wang et al., 2014a). PFAAs levels up to 1.06 mg/L,
with a mass load of 174 kg/d, were identified at downstream of the
FIP (Wang et al., 2016). The FIP is one of the largest production facilities
of the fluorochemical industry in Asia. It was founded in 1987and began
to produce polytetrafluoroethylene (PTFE) in 2001, with a production
capacity of 49,000 tons in 2013. This FIP also produces other
fluoropolymers (FP) that involve PFOA as a processing aid (Wang
et al., 2014a; Wang et al., 2016). While PFOA is largely released via the
production and use of Ammonium Perfluorooctanoate (APFO) (Wang
et al., 2014b), the C4–C7 PFCAs mainly come from impurities of PFCAs
in FP/fluoroelastomer (FE) products or degradation of FP precursors
(Shi et al., 2015).
This study provides a detailed and systematic investigation on the
concentration and distribution of PFAAs in indoor and outdoor dust
samples from households around the FIP. The objective was to deter-
mine the influence of PFAAs emitted from the FIP and estimate the
daily intake of dominant PFAAs present in dust.Such information is nec-
essary for effective management of PFAAs production from the FIP and
for human health risk assessment.
Fig. 1. (a) Map ofthe study area and sampling sites; (b)Spatial distribution of PFAAs in indoor dusts; (c)Relative abundanceof individual PFAA inindoor dusts; (d) Spatial distribution of
PFAAs in outdoordusts; (e) Relativeabundance of individualPFAA in outdoor dusts; (f)Comparison of PFAAs concentrationin indoor dust and outdoor dust.The lower and upper ends of
the box are the 25th and 75th percentiles of the data. Thehorizontal solid line within the box is the median value and the symbol ▲represents the arithmetic mean value.
2H. Su et al. / Environment International xxx (2016) xxx–xxx
Please cite this article as: Su, H., et al., Perfluoroalkyl acids (PFAAs) in indoor and outdoor dusts around a mega fluorochemical industrial park in
China: Implications for h..., Environ Int (2016), http://dx.doi.org/10.1016/j.envint.2016.07.002
2. Materials and methods
2.1. Sampling design and collection
The sampling sites are shown in Fig. 1a. With the FIP in Huantai as
the center, samples were taken with the radius of 2, 5, 10 and 20 km
in four directions (East, E; South, S; West, W; North, N). 16 pairs of in-
door and corresponding outdoor dusts samples were collected from
randomly selected homes at each sampling site in October of 2014. An
outdoor dust sample was also collected from a road in the FIP at the
same time. At each site, dust samples were swept with a pre-cleaned
brush from the inside and outside of the house, respectively. Individual
samples were wrapped in aluminum foil and further sealed in polyeth-
ylene zip bags, and then they were transported to the laboratory and
stored at −20 °C until analysis. Before chemical analysis, large debris
and particles (visible hairs, fibers or grits etc.) were removed from the
samples by using a methanol rinsed pair of tweezers.
2.2. Standards and reagents
A total of 12 native PFAAs, including perfluorobutanoic acid (PFBA),
perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA),
perfluoroheptanoic acid (PFHpA), PFOA, perfluorononanoic acid
(PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid
(PFUnDA), perfluorododecanoic acid (PFDoA), perfluorobutane sulfo-
nate (PFBS), perfluorohexane sulfonate (PFHxS), PFOS and 9 mass-
labeled PFAAs, including
13
C
4
PFBA,
13
C
4
PFHxA,
13
C
4
PFOA,
13
C
4
PFNA,
13
C
4
PFDA,
13
C
4
PFUnDA,
13
C
2
PFDoA,
18
O
2
PFHxS and
13
C
4
PFOS were pur-
chased from Wellington Laboratories with purities of N98% (Guelph,
Ontario, Canada). Detailed information about standards and reagents
is given in the Supplementary information.
2.3. Sample extraction and instrumental analysis
Samples were extracted according to published methods (Wang
et al., 2015) with some modifications. A sub-sample of 2 g dust was
spiked with 5 ng mass-labeled internal standards, digested with 2 mL
100 mM NaOH in acetonitrile and ultrasonicated for 30 min. A 20 mL
volume of acetonitrilewas added into the mixture and then the samples
were shaken at 250 rpm for 30 min. Subsequently, 0.1 mL 2 M HCl was
added, followed by centrifugation at 3000 rpm for 15 min. The process
of extraction of acetonitrile was repeated twice. The supernatants
were combined together and concentrated under a gentle flow of
high-purity nitrogen to 1 mL.
Clean-up was performed with solid phase extraction (SPE) using
ENVI-Carb cartridges and Oasis-WAX cartridges. Supelco ENVI-Carb car-
tridges (250 mg, 3 mL, Sigma-Aldrich, St. Louis, USA) were conditioned
with 1 mL methanol for three times, and then the extracts were loaded
and collected. The cartridges were further washed with 1 mL methanol
for three times and collected together with theextracts. All the extracts
were diluted in 100 mL Milli-Q water and subjected to Oasis WAX-SPE
cleanup. The Oasis WAX cartridges (6 cc
3
, 150 mg, 30 μm, Waters, Mil-
ford, MA) were conditioned with 4 mL of 0.1% ammonium hydroxide
in methanol, 4 mL methanol and 4 mL Milli-Q water successively.
After loading the extracts, the cartridges were washed with 4 mL
25 mM ammonium acetate (pH 4) and air-dried. The analytes were
eluted with 4 mL methanol, followed by 4 mL 0.1% ammonium hydrox-
ide in methanol. The eluate was then evaporated under gentle flow of
high-purity nitrogen to 1 mL, filtered through a 0.2 μm nylon filter,
and transferred into a 1.5 mL PP snap top brown glass vial with polyeth-
ylene (PE) septa for HPLC analysis.
All PFAAs were analyzed via an Agilent 1290 Infinity HPLC System
coupled to an Agilent 6460 Triple Quadrupole LC/MS System (Agilent
Technologies, Palo Alto, CA). The instrumentconditionsare listed in Ta-
bles S1, S2.
2.4. Quality control and quality assurance
To avoid contamination, PTFE and other fluoropolymer materials
were not used in sample preparation. Field blanks and procedural
blanks were prepared using anhydrous sodium sulfate as an alternative
of dust to monitor contamination during sample collection and extrac-
tion. Solvent blanks using methanol were run for every 10 samples to
check background interferences of the instrument. Matrix spike recov-
ery was performed with 50 ng native PFAAs standards added into 2 g
outdoor dust samples at site E4, S4, W4 and N4, respectively.
A10-pointinternalquantification curves ranging from 0.01 to
1000 ng/mL were prepared for the quantification of individual PFAAs
with coefficients of determination (r
2
) for all the target analytes higher
than 0.99. Where samples had concentrations of PFAAs higher than
1000 ng/mL, we reduced the amount and extracted again to make
sure the PFAAs concentrations in the extracts fell within the range of
the calibration series. Concentrations of all target PFAAs in any of field
and procedural blanks were less than the limit of detection (LOD),
which was defined as 3 times of signal-to-noise ratio (S/N). The limit
of quantification (LOQ) was set as 10 times of S/N. Matrix spike recover-
ies of PFAAs ranged from 73 to 118%. Detailed QA/QC measurements of
PFAAs in dust are shown in Table S3.
2.5. Statistical analysis
Data analysis was performed with SPSS Statistics V20.0 (SPSS Inc.,
USA) and Origin Pro 9.0 (Northampton, USA). For the purposes of this
analysis, where a detection was less than the LOD they were given a
value by dividing the LOD by the square root of two, and those less
than LOQ were set to half of the LOQ (Wang et al., 2014a). Spatial distri-
butions of PFAAs were analyzed using ArcGIS V10.0 (ESRI).
3. Results and discussion
3.1. PFAAs in indoor dusts
Concentrations of total PFAAs (ΣPFAAs) measured in indoor dust
samples ranged from 73 to 13,500 ng/g, with a median of 979 ng/g
(Table S4). The frequency of detection for C4 to C10 PFCAs and PFBS,
PFHxS and PFOS were 100%, and those of C11 and C12 PFCAs were
82% and 94%, respectively.
The mean concentrations of ΣPFAAs at 2, 5, 10 and 20 km sampling
circles were 6402, 1568, 812 and 243 ng/g, respectively. The concentra-
tions of ΣPFAAs decreased exponentially with the increase of distance
from the source (r
2
≥0.990) (Fig. 2). The mean ΣPFAAslevelsinindoor
dusts from the 2, 5 and 10 km circles were at least one order of magni-
tude greater than the median levels in house dusts from more contam-
inated areas such as UK (350 ng/g), Germany (517 ng/g) and the US
(619 ng/g), and they were also up to 2–3 orders of magnitude higher
than those from slightly polluted areas like Egypt (1.7 ng/g) and
Belgium (1.2 ng/g) (Shoeib et al., 2016).
For all indoor dust samples, PFOA (56–8873 ng/g) was found to be
the dominant PFAA, contributing 80.4% of ΣPFAAs, followed by short
chain PFCAs, including PFPeA (2.90–3362 ng/g, 6.3%), PFBA (5.82–
220 ng/g, 5.0%), PFHpA (1.34–662 ng/g, 3.9%), PFHxA (4.75–424 ng/g,
3.8%) (Fig. 1c). For the other long chain PFCAs and all PFSAs (2.16–
18.5 ng/g), the contribution to the total was b1%. The congener pattern
of PFAAs in dusts was consistent with that in surface water and sedi-
ment in this area, in which PFOA and short chain PFCAs dominated as
well (Wang et al., 2016). Like the congener pattern in the present
study, PFOA was found to be the predominant PFCA in many other
countries, such as Canada, Sweden, Spain or Australia (Eriksson and
Kärrman, 2015). The median concentration of PFOA (852 ng/g) in
house dust here was 1–2 orders of magnitude higher than that in
house dusts from these countries (9–21 ng/g) (Eriksson and Kärrman,
2015) and was also 4 times higher than the mean PFOA concentration
3H. Su et al. / Environment International xxx (2016) xxx–xxx
Please cite this article as: Su, H., et al., Perfluoroalkyl acids (PFAAs) in indoor and outdoor dusts around a mega fluorochemical industrial park in
China: Implications for h..., Environ Int (2016), http://dx.doi.org/10.1016/j.envint.2016.07.002
(205 ng/g) in indoor dusts from ordinary houses without a nearby point
source in China (Zhang et al., 2010).
3.2. PFAAs in outdoor dusts
The concentrations of ΣPFAAs in outdoor dusts ranged from 5 to
9495 ng/g (median: 62 ng/g) (Table S5). The highest ΣPFAAs concentra-
tion was found inthe dust collected from the road located in the FIP. De-
tection frequency of C4 to C9 and C12 PFCAs were 100% and that of C10
and C11 PFCAs were 94%, while the detection rate of PFBS and PFOS was
88% and that of PFHxS was 41%. With the increase in distance from the
FIP, the concentrations of PFAAs in outdoor dusts decreased (Fig. 1d).
Mean concentrations of ΣPFAAs for 2, 5, 10 and 20 km from the FIP
were 747, 319, 77.6 and 34.7 ng/g, which were about 13–274 times
lower than that in dusts from the FIP. The relative contributions of indi-
vidual PFAAs for indoor and outdoor dusts were similar (Fig. 1c, e).
PFOA (4.29–8511 ng/g) was the dominant PFAA and contributed
79.5% of ΣPFAAs, followed by PFBA (0.53–255 ng/g, 7.7%), PFPeA
(0.22–521 ng/g, 4.8%), PFHxA (0.15–108 ng/g, 3.1%), PFHpA (0.03–
82.2 ng/g, 3.1%) (Fig. 1e). Concentrations of C9–C12 PFCAs and all
PFSAs ranged from 0.17 to 16.6 ng/g.
Studies on PFAAs in outdoor dust are rare, although these dusts play
an important role in the global transportation of PFAAs (Yao et al.,
2016). PFOA levels ranged from 1.2 to 11 ng/g in street dust including
residential area and heavy traffic area in Japan (Murakami et al.,
2008), which were lower than PFOA concentrations (11–36 ng/g) in
outdoor dusts from 20 km away from the FIP. As for outdoor dust na-
tionwide in China (Yao et a l., 2016), C4–C12PFCAs as a whole accounted
for 89% of the PFAAs, among which PFOA was the predominant form as
well. In their study, the highest PFOA concentrations (65–100 ng/g) oc-
curred in outdoor dusts from Shanghai, one of the most urbanized cities
in China (Yao et al., 2016), which were N2–6 times lower than the mean
Fig. 2. Decline in C4–C8 PFCAs and ΣPFAAs concentrations in indoordust samples with the distance from the FIP. Thedecline curve was based on the arithmetic meanconcentration. The
lower and upper ends of the box are the 25th and 75th percentiles of the data. The horizontal solid line within the box is the median value and the symbol ▲represents the arithmetic
mean value.
4H. Su et al. / Environment International xxx (2016) xxx–xxx
Please cite this article as: Su, H., et al., Perfluoroalkyl acids (PFAAs) in indoor and outdoor dusts around a mega fluorochemical industrial park in
China: Implications for h..., Environ Int (2016), http://dx.doi.org/10.1016/j.envint.2016.07.002
concentrations of PFOA in dust samples from the 2 km (627 ng/g) and
5 km (254 ng/g) circles, and higher than those from 10 km (59 ng/g)
and 20 km (25 ng/g) circles in our study.
For each site, the concentrations of PFAAs measured in indoor dust
exceeded that measured in outdoor dust (Fig. 1f). The same phenome-
non has also been observed in other organic contaminants, like Fipronil
(Mahler et al., 2009), PBDEs (Yu et al., 2012), or PCBs (Wang et al.,
2013). Indoor dust particles have different properties from outdoor
such as in particle size, or organic content, potentially making them
more attractive sorbents fort PFAAs. Meanwhile, house dust is not sub-
ject to the same environmental conditions as outdoor dust (e.g., wind
and rain dispersal, runoff, moisture, sunlight). Therefore, elimination
or degradation of contaminants associated with dust is assumed to be
slower indoors than outdoors (Vorhees et al., 1999; Mahler et al., 2009).
3.3. Source identification of PFAAs in dust
Associations among different PFAAs concentrations in dusts were
explored using Spearman Rank Correlations (Tables S6, S7). PFCAs
from C4 (PFBA) to C8 (PFOA) were highly correlated (pb0.01, correla-
tion coefficients N0.85) with each other. Furthermore, a significant cor-
relation (pb0.05) was observed among the remaining PFCAs, while
associations within PFSAs as well as between PFCAs and PFSAs were
less significant. The associations among individual PFAAs indicated
that these congeners share similar origins or fate. A significant PFOA
and PFOS correlation in house dust which has been reported in many
studies (Kato et al., 2009; Haug et al., 2011a; Fraser et al., 2013)was
not observed here. This might be due to different dust PFAAs origins.
Correlation analysis of PFAA congeners between the central FIP
(C) and the other dust sampling sites (Tables S8, S9) showed that they
were similar in the signature profiles (pb0.01,correlation coefficients
N0.76). Based on our previous examination of the area (Wang et al.,
2014a), the FIP was the only point source in the study area, which gen-
erated the PFAAs contaminants in dust samples. The FIP is a self-
sufficient manufacturer, so the PFCAs could be generated and released
through their direct production, the production of fluoropolymers or
the production of many intermediates (Wang et al., 2016). Global
source inventories have also demonstrated that emissions of PFCAs
can be largely attributed to these processes (Wang et al., 2014b).
Spatially, PFAAs concentrations of dust samples in the west were
higher than that in other three directions, which were comparable to
each other (Fig. 1b, d). Wind rose plot for local area shows that the E
(east) wind and the ESE (east-south-east) wind are the primary wind
directions in the study area (Fig. 1a, S1). Hence, the downwind location
may be the main reason for higher concentrations of PFAAs at the sites
in the west. So air transport and deposition was the most likely pathway
for PFAAs from the FIP to the households in the surrounding areas,
which is similar to the APFO transportation in environmental media
near a fluorochemical manufacturing facility (Davis et al., 2007).
Correlations of PFAAs in indoor and outdoor dusts at each sample
site were also investigated (Table S10). The total PFAAs in the indoor
dust samples correlated well with that in the corresponding outdoor
dust samples (pb0.01,correlation coefficients N0.74), which implies
similar sources. It is possible that outdoor dust is walked into the houses
by the residents (Mahler et al., 2012). Indoor air and outdoor to indoor
air transport may contribute to the organic contaminants in indoor dust
as well (Mercier et al., 2011). The clothing and skin of workers who live
close to the FIP is possibly another source of PFAAs in dusts (Fu et al.,
2015). These sources of PFAAs in dusts around the FIP (Fig. 3)arediffer-
ent from those in ordinary homes where the source is use, wear and
abrasion of consumer products inside the home (Moriwaki et al.,
2003; Shoeib et al., 2005).
3.4. Human exposure to PFAAs via dust ingestion and dermal absorption
Humans can be exposed to PFAAs in dust via ingestion and dermal
absorption. The estimated daily intake (EDI, ng/kg·bw/day) of PFAAs
through dust ingestion and dermal absorption can be calculated by av-
eraging the intake dose over body weight, with equations and expo-
sure/ingestion factors recommended by the Environmental Protection
Agency of the United States (USEPA, 2011)andZhang et al. (2010,
2015). Considering that body weights and consumption rates vary by
age, we estimated the EDI of PFAAs for five age groups: infants (0–
1 years), toddlers (2–5 years), children (6–10 years), teenagers (11–
17 years), and adults (≥18 years). The details of the calculation and
data sources are shown in Table S11 and Table S12. As for the EDIcalcu-
lation of each sampling circle, arithmetic mean concentrations of PFAAs
were used.
The EDIs of several main PFAAs in the study area via dust ingestion
and dermal absorption varied, depending on the age group and the dis-
tance of the residents from the FIP (Table S13). The EDI of PFAAs
through dust ingestion was approximately 4–14 times higher than
that through dermal absorption. The total exposure of PFBA, PFPeA,
PFHxA, PFHpA, PFOA, and ΣPFAAs via dust were 0.184, 0.997, 0.196,
0.293, 4.42 and 6.09 ng/kg·bw/day for adults who reside about 2 km
away from the FIP, and corresponding exposures were 1.10, 5.81, 1.14,
1.70, 26.0 and 35.9 ng/kg·bw/day for toddlers, respectively (Table 1).
As expected, the EDI for toddlers was higher than those for other age
groups in each sample circle (Fig. 4) due to more frequent hand-to-
mouth contact, indicating that the dust imposes more potential health
risk on this age group. Tolerable daily intake (TDI) values are only avail-
able for PFOS and PFOA. Compared to current recommended TDI values
of 100 to 1500 ng/kg·bw/day for PFOA proposed by several countries
(Fig.4, Table S14), the EDI of PFOA via dust for residents in the study
Fig. 3. Schematic diagram of sources of PFAAs in dust around the FIP.
5H. Su et al. / Environment International xxx (2016) xxx–xxx
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China: Implications for h..., Environ Int (2016), http://dx.doi.org/10.1016/j.envint.2016.07.002
area are less than these limits. However, it is important to note that
there is an ongoing discussion about the relevance of these TDIs. Some
argue that these values are insufficiently protective and may be several
hundred fold too high (Grandjean and Budtz-Jørgensen, 2013;
Grandjean and Clapp, 2015). PTFE production has been expanded in
the FIP with an average annual growth rate of25% since 2001, and with-
out suitable substitutes for PFOA in the production of most
fluoropolymers (Wang et al., 2016), high exposure is likely to continue
for the local residents.
The EDIs of PFAAs via dust ingestion have been reported in the pre-
vious studies. Zhang et al. (2010) estimated PFOA intake via indoor dust
collected from four cities in China to be 0.87 ng/kg·bw/day for toddlers,
about 3 times higher than that for children and teenagers and adults,
and a little lower than the EDI of PFOA for toddlers living about 20 km
away from the FIP. The EDI of PFOA was 0.43 ng/kg·bw/day for adults
and 5.3 ng/kg·bw/day for children in Birmingham, UK (Goosey and
Harrad, 2011) and was 0.20 ng/kg·bw/day for adult women in
Norway (Haug et al., 2011b). The estimated intake of PFAAs (PFOA)
via dust ingestion by 2 years' children was between 2.5 (0.06) and 7.0
(0.11) ng/kg·bw/day in Australia, Canada, the Faroe Islands and Japan,
0.3–0.8 (0.04–0.06) ng/kg·bw/day in Greece, Spain, and Sweden, and
0.02 (0) ng/kg·bw/day in Nepal (Eriksson and Kärrman, 2015). Overall,
the estimated intakes of PFOA/PFAAs by residents about 2 km and 5 km
from the FIP in our study were highest compared with the values previ-
ously reported.
4. Conclusion
PFAAs in indoor and outdoor dusts were investigated around a mega
fluorochemical industrial park (FIP). PFAAs generated from the FIP have
diffused into the surrounding households and resulted in a zone of
PFAAs contamination, at least 20 km in radius. The signature of the
PFAAs in indoor and outdoor dust within this zone matches that within
the FIP facility. The plume shape is consistent with air transport from
the prevailing easterly winds from the FIP. PFOA and C4–C7 PFCAs
were the predominant PFAAs in all dust sampleswith average contribu-
tions over 79% and 19%, respectively. The levels of PFAAs were signifi-
cantly higher in indoor dusts than in outdoor dust. The entry of PFAAs
contaminated dusts into resident's houses is most likely associated
with entry via the window together with dusts being walked in.
The estimated daily ingestion dose of PFAAs for this area in China via
contaminated dusts was higher than any previously recorded around
the world, and the dusts impose more potential health risk on toddlers
than any other age groups. Until new replacement products emerge,
this high local exposure of residents to PFAAs via dust is likely to contin-
ue. In order to mitigate human exposure to fugitive gases and dusts
heavily contaminated with PFOA and other PFAAs released from the
FIP, scrubbers are suggested to be applied in smokestacks to capture
smoke and toxic gases as well as fine particulates, and health risk
awareness for the people (especially children) living in close proximity
to the FIP should be enhanced to prevent them from exposures. This
study identified primarily the sources of dust PFAAs and the possible
transport pathways of PFAAs from the FIP to surrounding areas. Further
investigation is needed for health risk assessment and management.
Acknowledgements
This study was supported by the International ScientificCooperation
Program with Grant No. 2012DFA91150, National Natural Science Foun-
dation of China under Grant No. 414201040045 and No. 41371488, and
the Key Project of the Chinese Academy of Sciences under Grant No.
KZZD-EW-TZ-12.
Appendix A. Supplementary data
Supplementary data to this article can be found online at http://dx.
doi.org/10.1016/j.envint.2016.07.002.
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- ReferencesReferences45
- [Show abstract] [Hide abstract] ABSTRACT: The exposure pathways of perfluoroalkyl acids (PFAAs) to humans are still not clear because of the complex living environment, and few studies have simultaneously investigated the bioaccumulative behaviour of different PFAAs in humans. In this study, serum, dust, duplicate diet, and other matrices were collected around a manufacturing plant in China, and homologous series of PFAAs were analysed. PFAA levels in dust and serum of local residents in this area were considerably higher than those in non-polluted area. Although dietary intake was the major exposure pathway in the present study, dust ingestion played an important role in this case. Serum PFAAs in local residents was significantly correlated with dust PFAAs levels in their living or working microenvironment. Serum PFAAs and dust PFAAs were significantly higher in family members of occupational workers (FM) than in ordinary residents (OR) (p < 0.01). After a careful analysis of the PFAAs exposure pathway, a potential pathway in addition to direct dust ingestion was suggested: PFAAs might transferred from occupational worker's clothes to dinners via cooking processes. The bioaccumulative potential of PFHxS and PFOS were higher than other PFAAs, which suggested a substantial difference between the bioaccumulative ability of perfluorinated sulfonic acids and perfluorinated carboxylic acids.
- [Show abstract] [Hide abstract] ABSTRACT: Perfluoroalkylated substances (PFAS) is the collective name for a vast group of fluorinated compounds, including oligomers and polymers, which consist of neutral and anionic surface active compounds with high thermal, chemical and biological inertness. Perfluorinated compounds are generally hydrophobic but also lipophobic and will therefore not accumulate in fatty tissues as is usually the case with other persistent halogenated compounds. An important subset is the (per)fluorinated organic surfactants, to which perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) belong. The analytical detection method of choice for PFOS and PFOA is currently liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS), whereas both LC-MS/MS and gas chromatography-mass spectrometry (GC-MS) can be used for the determination of precursors of PFOS and PFOA. There are few reports of analysis of food items using these methods. Due to the substantial lack of suitable analytical data, many assumptions have been made in order to derive exposure estimates. Therefore, figures on levels in food and exposure provided in this opinion should be taken as indicative. PFOS, PFOA and other perfluorinated organic compounds have been widely used in industrial and consumer applications including stain- and water-resistant coatings for fabrics and carpets, oil-resistant coatings for paper products approved for food contact, fire-fighting foams, mining and oil well surfactants, floor polishes, and insecticide formulations. A number of different perfluorinated organic compounds have been widely found in the environment.
- [Show abstract] [Hide abstract] ABSTRACT: In order to understand better the pathways for transport of ammonium perfluorooctanoate (APFO) from a point source, a focused investigation of environmental media (water and soil) near a fluoropolymer manufacturing facility (Site) was undertaken. Methods were developed and validated at 2 microg kg(-1) [the limit of quantitation (LOQ)] in soil, and at 50 ng l(-1) in water. Environmental media were sampled from a public water supply well field located north of the Site, across a river. The data suggest that APFO air emissions from the Site are transported to the well field, deposited onto the soil, and then migrate downward with precipitation into the underlying aquifer.
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