Environ. Sci. Technol. 2010, 44, 8075–8081
Polyfluorinated Compounds in Residential and Nonresidential Indoor Air V E R A L A N G E R , †,‡ A N N E K A T R I N D R E Y E R , * ,† A N D RALF EBINGHAUS† GKSS Research Center, Max Planck Str. 1, 21502 Geesthacht, Germany, and Leuphana University Lu ¨ neburg, Scharnhorststr 1, 21335 Lu ¨ neburg, Germany
Received July 14, 2010. Revised manuscript received September 17, 2010. Accepted September 20, 2010.
Indoor air concentrations of fifteen volatile per- and polyfluorinated compounds (PFCs) (five fluorotelomer alcohols (FTOHs), three fluorotelomer acrylates (FTAs), three perfluorinated sulfonamido ethanols (FASEs), and three perfluorinated sulfonamides (FASAs)) were determined in residential and nonresidential indoor air environments. Air samples were taken with passive samplers, consisting of XAD-4 impregnated polyurethane foam (PUF) disks in steel housings. Impregnated PUF disks were extracted by fluidized bed extraction (FBE) using methyl-tert-butyl ether/acetone (1:1) and analyzed by gas chromatography-mass spectrometry. Total PFC indoor air concentrations ranged from 8.2 to 458 ng m-3. Individual PFC concentrations were between 42 pg m-3 (6:2 FTA) and 209 ng m-3 (8:2 FTOH). Concentrations of total FTOHs, FTAs, and FASAs + FASEs ranged from 0.2 to 152 ng m-3 (FTAs), from 3.3 to 307 ng m-3 (FTOHs), and from 4.4 to 148 ng m-3 (FASAs + FASEs). Most elevated individual, group, and total PFC concentrations were detected in two stores selling outdoor equipment, one furniture shop, and one carpet shop. Indoor air concentrations were several orders of magnitude higher than published outdoor air concentrations indicating indoor air environments as sources for PFCs to the atmosphere. Concentrations were used to estimate human exposure to investigated PFCs.
Introduction In recent years, per- and polyfluorinated compounds (PFCs) including persistent ionic perfluorinated carboxylates (PFCAs) and perfluorinated sulfonates (PFSAs) have been detected in various environmental compartments, biota, and humans on a global scale (1–5). Principally, PFCs are transported by two main mechanisms in the environment. First, (particularly ionic) PFCs travel long distances by transport with ocean currents (5–7). Second, nonpersistent, volatile, and neutral PFCs (the so-called “precursor” PFCs), including fluorotelomer alcohols (FTOHs), fluorotelomer acrylates (FTAs), perfluoroalkylsulfonamids (FASAs), and perfluoroalkylsulfonamido ethanols (FASEs), are transported in the atmosphere (1, 3, 8, 9). During their transport within the * Corresponding author present address: Eurofins GfA GmbH, Stenzelring 14, 21107 Hamburg, Germany; e-mail: annekatrindreyer@ eurofins.de; phone: +49-4152-872352; fax: +49-4152-872332. † GKSS Research Center. ‡ Leuphana University Lu ¨ neburg. 10.1021/es102384z
2010 American Chemical Society
Published on Web 10/06/2010
atmosphere, these compounds undergo OH radical-initiated transformation to yield the persistent acids (10–12). The estimated atmospheric lifetimes of individual precursors (2-80 days) are mostly long enough to ensure long-range atmospheric transport to remote regions of the earth (1, 10, 13, 14). Global perfluorooctanesulfonyl fluoride (POSF)-production from 2002 onward is likely to be about 1000 tonnes (t) per year (15). Total global POSF-related emissions to water and air were between 6800 and 45 250 t in the years 1970-2002 (15). Estimated total emissions of perfluorooctane sulfonate (PFOS)-related substances and PFOS-polymers in the EU for the year 2000 were 174 t (16). The worldwide production of FTOHs during the years 2000 and 2002 was 5000 t per year, and increased to currently 11 000-14 000 t per year (17). Whereas it is expected that PFCAs and PFSAs are mostly emitted directly to aqueous phases during manufacture and use (6, 15), the emission sources of volatile PFCs are more diffuse, as they are not only directly emitted to the atmosphere during manufacture of related products, but can also be released indirectly into the atmosphere as components or impurities of the final products (17–19). The molecular structure of PFCs includes a hydrophobic per- or polyfluorinated alkyl chain and a lipophobic functional moiety which makes the PFC molecule amphiphilic (20). Therefore polyfluorinated surfactants have beneficial properties as both water and oil repellents (20). Common and important fields of application of PFCs are carpet protection, paper and board protection, textile protection, leather protection, specialty surfactants and polymerization aids, metal plating, photographic and photolithographic uses, semiconductor industries, hydraulic fluids, and aqueous firefighting foams (6, 15, 16, 18–20). FASAs and FASEs were predominantly applied as intermediates in the production of perfluorinated products or as add-ons in polymers or other substances (20, 21). FTOHs were mainly used for paper coatings, food packaging, and carpet treatments (17, 20) and have been detected in microwave popcorn bags (22, 23), nonstick cookware (23), impregnating agents, and other household consumer products (18, 19). FTAs are used in the manufacture of FTOH-based polymers (10). In contrast to PFCAs and PFSAs sources to the aquatic system, specific sources of volatile precursor PFCs to the atmosphere are less known. Generally, elevated concentrations were observed in air masses arriving from populationand/or industry-rich areas, indicating a rather diffuse emission pattern (24). Furthermore, enhanced concentrations of selected PFCs were observed in indoor air (9, 25–28). However, although indoor contamination may be a significant exposure route for humans (29) and a potentially important source for airborne PFCs in the environment, detailed investigations on PFCs in indoor air or indoor air as a source for PFCs in the atmosphere are still lacking. The objective of this study was to determine indoor air concentrations of volatile PFCs at locations that can be regarded as being possible sources for the release of volatile PFCs. Therefore, PFC indoor air contamination was determined in several shops selling products potentially containing PFCs. These concentrations are to be compared to those observed at residential indoor air sampling sites.
Materials and Methods Chemicals. All standard compounds, chemicals and gases used were of high quality and purity. Details on manufacturers, purities, and abbreviations are given in the Supporting Information (Table S1). VOL. 44, NO. 21, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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Preparation of the Sampling Material. Passive sampling media were prepared as described by Shoeib et al. (26). PUF disks (14 cm ×1.35 cm, surface area 365 cm-2, mass 4.4 g, density 0.00213 g cm-3, Tisch Environmental, Cleves, OH) were cleaned by ultrasonication with acetone three consecutive times, dried in a clean lab, and stored in glass jars. Amberlite XAD-4 polymeric resin (GFS chemicals, Powell, OH) was ground in a ball mill (Retsch, Haan, Germany) and cleaned with acetone and dichloromethane for 24 h each, using Soxhlet extraction. Powdered XAD-4 (6.5 g) was suspended in 1 L of hexane and thoroughly stirred. This suspension was used to impregnate a set of ten PUF-disks (which are thus referred to as sorbent-impregnated (SIP) disks in the text). Each disk was dipped and pivoted in the suspension three times, then dried in a clean lab, and stored in a Petri dish. SIP disks were impregnated with an average XAD-4 mass of 450 (( 87) mg. Recently, these SIP disks proved to be suited for determining volatile PFCs in outdoor air (30). Steel housings were cleaned in a dishwasher, manually wiped with acetone, and stored in a clean lab. They were wiped with acetone again just before sampling. Sampling. Indoor air samples were taken in April-May 2009 and March 2010 in and around Hamburg, Germany in the following 16 locations: 2 furniture shops (FS 1; FS 2), 2 stores selling outdoor equipment (OS 1; OS 2), 2 printing shops (PRI 1; PRI 2), 2 residential houses (H 1; H 2), 2 offices (OF 1; OF 2), 2 auto body shops (ABS 1; ABS 2), 1 powder coating service (COS), 1 carpet shop (CAS), 1 electroplating service (EP), and 1 car selling shop (CAR). FS 1 was a threestory building mainly selling upholstery. FS 2 consisted of only one salesroom and was selling mainly wood furniture. Sampling at OS was conducted in the storage room (OS 2a) and in the sales room adjacent to the storage room (OS 2b). Sampling at OS 1 was conducted only in the storage room. The density of selling items in storage rooms was higher than that in sales rooms. The storage room at OS 2 was about three times as big as that at OS 1. Both residential houses were noncarpeted. OF 1 was newly painted. OF 2 was newly carpeted. ABS 1 and ABS 2, as well as PRI 1 and PRI 2, were about the same size. CAR was selling new cars only. Passive samplers were used to collect air samples. Analytes were trapped on SIP disks which were placed in protective stainless steel housings. Prior to taking real samples, a field calibration was performed to determine the passive sampler uptake behavior for the target analytes (Figures S1, S2, S3 in the Supporting Information). As result, samples were taken for a period of 14 days. Passive samplers were deployed as duplicates at all sampling locations. Placing samplers close to windows and ventilation shafts or in direct sunlight was avoided. After sampling, SIP disks were sealed airtight and stored at -20 °C until extraction. Sampling Preparation and Instrumental Analysis. SIP disks were extracted by fluidized bed extraction (FBE) using 200 mL of acetone/methyl-tert-butyl ether (MTBE) (1:1; v:v) as solvent. Prior to the extraction, PUF disks were spiked with 80 µL of a solution containing the following mass-labeled internal standards: 13C 4:2 FTOH, 13C 6:2 FTOH, 13C 8:2 FTOH, 13 C 10:2 FTOH, EtFOSA D5, MeFOSA D3, MeFOSE D7, and EtFOSE D9 (750 µg mL-1). Samples were extracted in three consecutive heating and cooling cycles. For each cycle, samples were heated up to and kept at 70 °C for 30 min and then cooled down to 30 °C. After FBE extraction, solvent was reduced to 5 mL using rotary evaporators at a pressure of 420 mbar and a temperature of 30 °C. Solvent was further reduced under a gentle stream of preheated nitrogen to a volume of 150 µL, using ethyl acetate as a keeper. Samples were transferred to amber vials and 50 µL of the injection standard 13C TCB (400 pg µL-1) were added. Analytes were separated by gas chromatography and detected by mass spectrometry (GC-MS) using positive 8076
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chemical ionization (PCI) and the selective ion monitoring (SIM) mode. Details on instrumental parameters are given by Dreyer et al. (24). Analyte concentrations were calculated using a seven-point calibration (10-200 pg µL-1) and recovery-corrected by mass-labeled internal standards. Calculation of Indoor Air PFC Concentrations. Indoor air PFC concentrations were calculated applying eq 1: CA ) M/[kA × ASIP × t]
(1)
where CA is the indoor air contamination of the analyte (pg m-3), M is the total mass of analyte sequestered on the SIP disk (pg), kA is the airside mass transfer coefficient of the analyte (m d-1), ASIP is the surface area of the SIP disk (0.00365 m2), and t is the deployment time (14 days). Shoeib et al. (26) published kA values for 8:2 FTOH, 10:2 FTOH, MeFOSE, EtFOSA, and EtFOSE (Table S2). For the remaining target analytes investigated in this study, kA values were estimated (Table S2). Statistical Analysis. Statistical analysis was performed using Winstat version 2007. The Kolmogorov-Smirnov test was applied to determine whether analyte compositions were normally distributed. Cluster analysis applying the WARD agglomeration method (sometimes also referred to as “incremental sums of squares method”) was performed on normally distributed PFC compositions. The number of clusters was determined according to the elbow-criterion. Quality Assurance/Quality Control. PFC-containing equipment was avoided during sampling and sample preparation. Glassware and sampling equipment were thoroughly cleaned with water and solvent before use. If possible, they were also heated to 250 °C for 12 h. A passive sampler calibration was performed to investigate the analyte uptake of the sampling medium. Seven-point calibrations were run with each set of samples measured. Compound-specific mass-labeled internal standards were used to account for analyte losses (Table S3). Field and laboratory blanks were regularly taken (Table S4). Laboratory blanks were taken for each set of seven PUF disks extracted. Contamination, if detected at all, was found to be irrelevant relative to PFC concentrations of the samples which were several orders of magnitude higher than blank concentrations. The combined uncertainty of the method was calculated on the basis of paired measurements according to ISO 20988 (31) and was on average 29% for high concentration sites and 49% for low concentration sites (Table S5). Estimation of the General Exposure to PFC from the Investigated Sites. Indoor air concentrations (Table 1) were used to get a rough worst case estimate of the chronic daily human exposure to determined PFCs resulting from staying at the investigated locations (eq 2). Ei,A ) CA × Rair × Fuptake /MBW
(2)
Ei,A is the estimated daily exposure to the analyte (A) in a certain indoor air environment (ng d-1 kg-1 b.w.). CA is the measured indoor air concentration of the analyte (ng m-3). MBW is the body weight (kg b.w.) which was set to 60 kg for an adult person (32). Rair is the total daily air volume inhalation rate (m3 d-1). It is assumed to be 13.3 m3 (33). Fromme et al. (32) assumed that people generally spend 90% (21.6 h) of their daytime indoors and 10% (2.4 h) outdoors, resulting in a total inhalation rate of about 12 m3 d-1 of indoor air. We assumed that the general human spends 8 h per day at work. Therefore, Rair for all nonresidential indoor air environments was set to 4.43 m3 d-1. Rair for residential indoor air environments (H 1, H 2) was set to 7.54 m3 d-1 (corresponds to 13.6 h). Fuptake is the uptake fraction of PFCs and was set to 1 (i.e., complete uptake). Metabolism of PFCs or their elimination was not considered.
TABLE 1. Average (n = 2) PFC Indoor Air Concentrations (ng m-3)a ng/m3
H1
H2
OF 1
OF 2
COS
CAR
PRI 1
PRI 2
ABS 1
ABS 2
EP
FS 1
FS 2
CAS
OS 1
OS 2a
OS 2b
4:2 FTOH 6:2 FTOH 8:2 FTOH 10:2 FTOH 12:2 FTOH 6:2 FTA 8:2 FTA 10:2 FTA EtFOSA MeFBSA MeFOSA MeFOSE MeFBSE EtFOSE
0.8 1.1 8.1 1.9 0.8 n.d. 0.2 0.7 1.2 n.d. 1.0 2.7 2.4 2.1
1.2 2.9 17.4 5.1 1.7 0.2 1.5 1.1 1.6 n.d. 1.2 3.1 2.6 2.2
0.04 3.4 5.5 2.4 1.5 3.4 7.5 2.1 1.5 0.4 0.6 2.0 1.5 1.5
1.1 6.0 4.3 1.1 0.5 0.2 2.6 0.5 1.2 n.d. 0.8 2.3 3.5 2.1
n.d. 1.1 2.3 0.8 0.5 0.1 0.6 0.1 0.8 0.6 0.5 1.0 1.0 1.2
0.4 1.8 13 5.7 3.9 0.3 1.4 0.5 0.4 n.d. 2.4 7.6 17 12
0.3 2.1 62 0.5 0.5 0.2 0.5 0.2 0.1 2.1 0.7 10 9.2 11
0.4 3.5 5.8 1.2 1.0 0.3 0.6 1.9 0.3 0.3 0.1 10 11 11
n.d. 0.6 1.9 0.5 0.2 0.2 0.3 0.1 0.8 0.4 0.5 1.1 0.6 0.9
0.6 5.1 14 2.9 1.8 0.3 0.5 0.1 1.1 3.4 1.5 7.7 9.7 8.3
1.0 0.1 1.1 0.1 1.1 0.1 0.1 0.1 1.2 1.0 1.2 1.3 2.6 1.7
n.d. 1.3 3.0 0.9 0.4 0.1 0.6 0.1 1.1 0.8 1.1 1.6 6.3 1.4
n.d. 33 164 44 16 1.8 67 8.4 1.5 1.2 1.5 1.3 4.2 2.0
n.d. 9.9 15 4.1 16 0.2 0.9 1.6 0.5 2.8 0.7 2.0 141 0.7
0.2 20 209 48 17 2.9 132 16 1.0 0.8 0.8 1.2 7.1 1.0
n.d. 37 196 54 19 2.5 86 11 1.6 1.4 1.6 1.2 4.0 1.9
n.d. 13 79 28 10 1.0 23 5.9 1.0 0.6 0.9 1.6 4.2 9.0
Σ FTOH Σ FTA Σ FASA/E
13 0.9 9.4
28 2.8 11
13 13 7.6
13 3.3 9.8
4.7 0.7 5.0
25 2.3 39
66 0.8 33
12 2.8 32
3.3 0.6 4.4
25 0.8 32
3.4 0.2 9.0
5.7 0.8 12
257 77 12
45 2.7 148
294 152 12
307 100 12
130 30 17
Σ PFC
23
42
33
26
10
66
100
47
8.2
57
13
19
346
196
458
418
177
a
n.d.: not detected. FS: furniture shop, OS: store selling outdoor equipment, PRI: printing shop, H: residential house, OF: office, ABS: auto body shop, COS: powder coating service, CAS: carpet shop, EP: electroplating service, CAR: car selling shop. Note that sample OF1b was lost during laboratory work-up (i.e., nOF1 ) 1).
FIGURE 1. Average (n ) 2) PFC concentrations (ng m-3) in indoor air. FS: furniture shop, OS: store selling outdoor equipment, PRI: printing shop, H: residential house, OF: office, ABS: auto body shop, COS: powder coating service, CAS: carpet shop, EP: electroplating service, CAR: car selling shop. Note that sample OF1b was lost during laboratory workup.
Results An overview about concentrations of volatile PFCs in indoor air is given in Table 1 and Figure 1. Total PFC concentrations ranged from 8.2 (ABS 1) to 458 ng m-3 (OS 1). Sum concentrations for FTAs ranged from 0.2 (EP) to 152 ng m-3 (OS 1), for FTOHs from 3.3 (ABS 1) to 307 ng m-3 (OS 2a), and for FASAs + FASEs from 4.4 (ABS 1) to 148 ng m-3 (FS 2). Individual PFC concentrations determined in this study ranged from 42 pg m-3 (6:2 FTA, H 1) to 209 ng m-3 (8:2 FTOH, OS 1). FTOHs were the predominant analyte group in most of the samples (Figure 2). Except for CAS (72% MeFBSE), 8:2 FTOH was observed in highest proportions. The results of the cluster analysis are given in Figure 3. According to their composition, sites can be divided into the following four clusters: cluster 1 (ABS 1, ABS 2, COS, EP, FS 1), cluster 2 (PRI 1, PRI 2, H 1, H 2, OF 1, OF 2, CAR) cluster 3 (FS 2, OS 1, OS 2a and OS 2b), and cluster 4 (CAS). Table 2 displays the chronic human exposure to volatile PFCs in the specific residential and nonresidential build-
ings. Total human exposure ranged from 0.6 (ABS 1) to 33.8 (OS 1) ng d-1 kg-1 b.w. and was usually highest for 8:2 FTOH and MeFBSE.
Discussion Overall PFC Contamination. Of the sites investigated in this study, high and low concentration locations became obvious (Figure 1, Table 1). Sites of low PFC air concentrations are H 1, H 2, OF 1, OF 2, COS, ABS 1, ABS 2, PRI 1, PRI 2, CAR, EP, and FS 1. Sites of high PFC air concentrations are FS 2, CAS, OS 1, OS 2a, and OS 2b. On average, these sites’ total PFC concentrations differed by a factor of 50. Concentrations of individual analytes were up to 2000 times higher at high contamination sites than at low contamination sites. Results of the cluster analysis (Figure 3) and thus PFC composition generally supported the separation of sampling locations into low and high PFC contamination sites. Clusters 1 and 2 consist of low contamination sites. Clusters 3 and 4 are composed of high contamination sites (see below). VOL. 44, NO. 21, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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FIGURE 2. Average (n ) 2) PFC composition in indoor air.. FS: furniture shop, OS: store selling outdoor equipment, PRI: printing shop, H: residential house, OF: office, ABS: auto body shop, COS: powder coating service, CAS: carpet shop, EP: electroplating service, CAR: car selling shop. Note that sample OF1b was lost during laboratory workup.
FIGURE 3. Results of cluster analysis. Cluster analysis was performed on the analyte composition. Proportions of 4:2 FTOH and 6:2 FTA were not included due to a lack of normal distribution. FS: furniture shop, OS: store selling outdoor equipment, PRI: printing shop, H: residential house, OF: office, ABS: auto body shop, COS: powder coating service, CAS: carpet shop, EP: electroplating service, CAR: car selling shop. Note that sample OF1b was lost during laboratory workup. High Concentration Sites. Total PFC concentrations at the high concentration sites ranged from 177 (OS 2b) to 458 ng m-3 (OS 1). Similar composition of analytes was observed at all sites of cluster 3 (FS 2, OS 1, OS 2a, and OS 2b). These samples were dominated by FTOHs and FTAs (>90%), with 8:2 FTOH and 8:2 FTA observed at highest concentrations. Contribution of FASAs and FASEs to the overall PFC contamination was less than 10% and their concentrations were in the same order of magnitude as those detected at the low concentrations sites. Thus, the high PFC contamination of FS 2, OS 1, OS 2a, and OS 2b is due to strongly elevated FTOH and FTA concentrations. The stores selling outdoor equipment that were sampled in this study were selling a similar range of products (sleeping bags, tents, waterproof shoes, and clothing). At both sites, storage rooms had no windows or air conditioning and ventilation was only enabled by the exchange of air through the doors to adjacent selling rooms. Although of different size, analyte concentrations in storage rooms of OS 1 and OS 2 (OS 2a) were quite similar, indicating that the density of selling items is an important parameter influencing the 8078
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magnitude of PFC indoor air concentrations. This was also confirmed by PFC concentration differences observed between OS 2a (higher density of selling items) and the adjacent sales room OS 2b (lower density of similar selling items, room size three times larger). Surprisingly, almost the same analyte composition as that of both stores selling outdoor equipment was observed at furniture shop 2. FS 2 was mainly selling wooden items, unlike FS 1 which contained a broad spectrum of furniture (e.g., furniture, upholstery, carpets, etc., made of different materials). Whereas the origin of PFC contamination in FS 2 is not known, it can be concluded that items available from both stores selling outdoor equipment (such as tents, clothes, or shoes) are impregnated with FTOH or FTA-containing agents to a high degree. This is supported by several studies that observed FTOH contaminations in waterproofing agents and outdoor clothing (16, 18, 19). FASA and FASE impregnations appeared to be less often used for these items, possibly due to the phase-out of long-chain PFSA derivatives (34). In contrast to the other high contamination sites, the carpeting shop (cluster 4) was characterized by different analyte composition (75% FASAs + FASEs). With about 25%, proportions of FTOHs were much lower than its proportion average. The FTA contribution at the carpet shop appeared to be insignificant compared to the remaining PFC classes. CAS was characterized by a remarkably high contamination with MeFBSE (141 ng m-3) which was 8-fold to 58-fold higher than concentrations determined at the remaining sampling locations of this study. FASEs were frequently applied for carpet treatment and strongly elevated MeFOSE concentrations were detected in samples taken within a region where the North American carpet manufacturing and treatment industry is located (8). The strongly elevated MeFBSE signal observed at the carpet selling store may reflect substitution of long-chain PFAS derivatives (C g 8) by their short-chain analogues (34). Low Concentration Sites. Overall, total PFC concentrations of low concentration sites were less than 100 ng m-3. Except for 4:2 FTOH and MeFBSA in a few samples, all analytes were detected. Cluster analysis indicated a further subdivision of low concentration sites into residential homes and “regular” working environments (CAR, H 1, H 2, OF 1, OF 2, PRI 1, PRI 2; cluster 2) and rather “industrial” locations
TABLE 2. Estimated Exposure of General People of Western Countries to PFCs Resulting from Indoor Air Inhalation (ng d-1 kg-1 b.w.)a Rair
H1 7.54
H2 7.54
OF 1 4.43
OF 2 4.43
COS 4.43
CAR 4.43
PRI 1 PRI 2 ABS 1 ABS 2 4.43 4.43 4.43 4.43
EP 4.43
FS 1 4.43
FS 2 4.43
CAS 4.43
OS 1 4.43
OS 2a 4.43
OS 2b 4.43
4:2 FTOH 6:2 FTOH 8:2 FTOH 10:2 FTOH 12:2 FTOH 6:2 FTA 8:2 FTA 10:2 FTA EtFOSA MeFBSA MeFOSA MeFOSE MeFBSE EtFOSE
0.09 0.12 0.87 0.20 0.09 n.d. 0.02 0.08 0.13 n.d. 0.11 0.29 0.26 0.23
0.13 0.31 1.87 0.55 0.18 0.02 0.16 0.12 0.17 n.d. 0.13 0.33 0.28 0.24
n.d. 0.07 0.22 0.38 0.35 0.27 0.15 0.07 0.10 0.03 0.22 0.01 0.48 0.16 0.13 0.03 0.10 0.08 0.03 n.d. 0.04 0.05 0.13 0.15 0.10 0.22 0.10 0.13
n.d. 0.07 0.15 0.05 0.03 0.01 0.04 0.01 0.05 0.04 0.03 0.06 0.06 0.08
0.03 0.11 0.82 0.36 0.25 0.02 0.09 0.03 0.03 n.d. 0.15 0.48 1.08 0.76
0.02 0.13 3.93 0.03 0.03 0.01 0.03 0.01 0.01 0.13 0.04 0.63 0.58 0.70
0.03 0.22 0.37 0.08 0.06 0.02 0.04 0.12 0.02 n.d. 0.01 0.63 0.70 0.70
n.d. 0.04 0.12 0.03 0.01 0.01 0.02 0.01 0.05 0.03 0.03 0.07 0.04 0.06
0.04 0.32 0.89 0.18 0.11 0.02 0.03 0.01 0.07 0.22 0.10 0.49 0.61 0.53
0.06 0.01 0.07 0.01 0.07 0.01 0.01 0.01 0.08 0.06 0.08 0.08 0.16 0.11
n.d. 0.08 0.19 0.06 0.03 0.01 0.04 0.01 0.07 0.05 0.07 0.10 0.40 0.09
n.d. 2.12 10.39 2.79 1.01 0.11 4.24 0.53 0.10 0.08 0.10 0.08 0.27 0.13
n.d. 0.63 0.95 0.26 1.01 0.01 0.06 0.10 0.03 0.18 0.04 0.13 8.93 0.04
0.01 1.29 13.24 3.04 1.08 0.18 8.36 1.01 0.06 0.05 0.05 0.08 0.45 0.06
n.d. 2.38 12.41 3.42 1.20 0.16 5.45 0.70 0.10 0.09 0.10 0.08 0.25 0.12
n.d. 0.84 5.00 1.77 0.63 0.06 1.46 0.37 0.06 0.04 0.06 0.10 0.27 0.57
Σ FTOH Σ FTA Σ FASA/E
1.40 3.01 0.82 0.10 0.30 0.82 1.01 1.18 0.48
0.82 0.30 1.58 0.21 0.04 0.15 0.62 0.32 2.47
4.18 0.05 2.09
0.76 0.18 2.03
0.21 0.04 0.28
1.58 0.05 2.03
0.22 0.36 16.28 2.85 0.01 0.05 4.88 0.17 0.57 0.76 0.76 9.37
Σ PFC
2.48 4.52 2.09
1.65 0.63 4.18
6.33
2.98
0.52
3.61
a
3
18.62 19.44 8.23 9.63 6.33 1.90 0.76 0.76 1.08
0.82 1.20 21.91 12.41 29.01 26.47 11.21 -1
n.d.: not detected. Rair: total daily air volume inhalation rate (7.54 m d for residential indoor air environments, 4.43 m3 d-1 for non-residential indoor air environments). The exposure estimate accounts only the time the general person will stay in the certain indoor environment (i.e., 8 h at work, 13.6 h at home). FS: furniture shop, OS: store selling outdoor equipment, PRI: printing shop, H: residential house, OF: office, ABS: auto body shops, COS: powder coating service, CAS: carpet shop, EP: electroplating service, CAR: car selling shop.
(COS, ABS 1, ABS 2, FS 1, EP; cluster 1). The origin of PFC contamination at these locations can only be guessed. At sites of cluster 2, concentrations of FTOHs usually exceeded those of FASAs + FASEs. In comparison to most other low contaminated sites, H 1 and H 2 contained elevated FTOH (particularly 8:2 FTOH) proportions. Since there were no carpets in either of the houses, this is probably due to the application of household impregnating items such as shoeimpregnation sprays or the existence of impregnated jackets and shoes in both households. These products have been previously observed to contain FTOHs (16–19). Elevated FTA concentrations of about 40% were detected in OF 1 which may have been caused by paint additives, as the office had been freshly painted. Although in the same cluster, the printing shops PRI 1 and PRI 2 were characterized by different analyte compositions. In contrast to PRI 2, PRI 1 was composed of an elevated 8:2 FTOH concentration. The use of FTOHs in paper coatings has been described before (16).
Therefore, the observed differences may be due to different types of coated paper used in the sampled printing shops. The car selling shop (CAR) contained elevated FASA and FASE concentrations and proportions which were likely caused by the use of FASA- and FASE-containing varnishes and textile/ leather protection agents (16, 19). Cluster 1 sites represent locations of lowest PFC contamination observed in this study. FASA + FASE concentrations exceeded those of FTOHs. The coating service and both auto body shops were characterized by very similar analyte compositions, possibly caused by the application of similar varnishes or coatings in those shops. Although not to the same extend as at CAS, an elevated MeFBSE proportion was observed at FS 1, which may be explained by the predominance of upholstery in this furniture shop and suggests that carpets and upholstery are rather impregnated with FASAand FASE-containing products (as did results of CAS), where-
TABLE 3. Published PFC Indoor Air Concentrations (pg m-3)a residential houses
analyte 4:2 FTOH 6:2 FTOH 8:2 FTOH 10:2 FTOH 12:2 FTOH MeFOSA MeFOSE EtFOSA EtFOSE
laboratory
library
office
Tromsø, Norway Ottawa, Canada Northern Norway Canada Canada Canada Germany 2005 2002/2003 2008 2001/2003 2001/2003 2005/2006 2007 HVS PAS HVS HVS HVS PAS LVS Barber et al. (9) Shoeib et al. (27) Huber et al. (28) Shoeib et al. (35) Shoeib et al. (35) Shoeib et al. (26) Jahnke et al. (25) 114 2990 3424 3559 n.a. 6600 6018 6626 5755
n.a. n.a. n.a. n.a. n.a. 35 1970 59 1100
24 9830 11100 n.a. n.a. n.a. n.a. 147 n.a.
n.a. n.a. n.a. n.a. n.a. 5-283 667-8300 n.a. 289-1800
n.a. n.a. n.a. n.a. n.a. n.a. 1700 n.a. 1917
n.a. 1680 3350 1700 n.a. n.d. 273 86 188
n.d. 177-248 421-853 898-1660 n.a. n.d. 727-798 158-188 305-815
a n.a.: not analyzed. n.d.: not detected. HVS: high volume sampling. LVS: low volume sampling. PAS: passive air sampling.
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as wooden furniture (FS 2) may rather be impregnated with FTOH- and FTA-containing products. Comparison of Residential and Nonresidential PFC Indoor Air Contamination. The two residential homes sampled in this study belong to the low contaminated sites. However, not only residential houses, but also most of the indoor air samples of this study were characterized by low PFC air concentrations. Thus, residential houses do not necessarily contain lower PFC air concentrations than buildings in which PFC-containing goods potentially may be applied or sold. Yet, all highly contaminated sites of this study were nonresidential. Therefore, it can be concluded that the PFC contamination of indoor air in houses is, compared to some other indoor air environments investigated in the present study, low, although it is still about 1 order of magnitude higher than in outdoor air (see below). Nonresidential sites can be either lowly or highly contaminated, depending on the amount/density and type of PFCcontaining products in the location. For further investigations, the number of samples taken at both residential and nonresidential houses needs to be increased. Comparison to PFC Previously Determined Indoor and Outdoor Air. Individual PFC indoor air concentrations and compositions observed in the present study are generally consistent with previous findings for FTOHs, FASAs, and FASEs in residential houses, laboratories, libraries, and offices (9, 25–28, 35) (Table 3). To date, FTA concentrations were not determined in indoor air. In the aforementioned studies, PFC air concentrations were in the same order of magnitude as those observed at low concentration sites. FTOH concentrations of the present study’s high contamination sites were up to 50-fold higher than those already published. Overall, this and other studies (6, 16–19) indicate a widespread application and use of PFC-containing products by consumers in households or by industry which potentially results in low-level PFC contamination of indoor air and similar substance composition. Elevated PFC concentrations as observed in the present study were likely caused by an accumulation of PFC-containing items or specialized application using particular substances (e.g., MeFBSE concentration at CAS). This study’s individual indoor air PFC concentrations were several orders of magnitude higher than published PFC outdoor air concentrations, indicating that indoor air is likely to be an important source of PFCs in the atmosphere. This may also explain elevated PFC outdoor air concentrations observed in air masses from areas of high population density (24), which were several orders of magnitude higher than those observed in marine background areas (1, 3). Outdoor air PFC samples were characterized by proportions of up to 80% of FTOHs followed by FASEs, FTAs, and FASAs (1, 3, 9, 24). Results of this study demonstrate that indoor air PFC composition (Figure 2, Tables S7, S8) was less uniform than that observed in outdoor samples. This study also reveals that FTOHs are the dominant compounds in indoor air and thus supports findings in outdoor air assuming that PFC outdoor air concentrations are significantly influenced by indoor sources. Estimation of the General Exposure to PFC from the Investigated Sites. Exposure to volatile PFC in the present study is lower than that resulting from the application of consumer products (18) and up to 1 order of magnitude higher than that summarized by Fromme et al. (32) Total daily intake (low-exposure to high-exposure) of the general population of an industrialized country was estimated to range 4-520 ng d-1 kg-1 b.w. (36), 3-220 ng d-1 kg-1 b.w. (37), or 1.6-8.8 ng d-1 kg-1 b.w. (32) for PFOS, and 0.3-140 ng d-1 kg-1 b.w. (36), 0.4-130 ng d-1 kg-1 b.w. (37), or 2.9-12.6 ng d-1 kg-1 b.w. (32) for perfluorooctanoate (PFOA). With the conservative estimate, that 5% of the FTOHs are 8080
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transformed to PFOA and 20% of the FOSAs + FOSEs are transformed to PFOS (32), volatile precursors as determined in the present study have only negligible contribution to the adult PFOA and PFOS exposure resulting from staying at the investigated places. Thus, precursor-based PFOA and PFOS exposure is of rather low importance for the general western population which generally confirms previously published data (32, 36).
Acknowledgments We thank all people who enabled sampling at their shops, residential houses, and offices.
Supporting Information Available Details of the method, results, and sample calibration. This material is available free of charge via the Internet at http:// pubs.acs.org.
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