Environ. Sci. Technol. 2009, 43, 2276–2281
Perfluoroalkyl Compounds (PFCs) in Indoor Dust: Concentrations, Human Exposure Estimates, and Sources ¨ RKLUND, JUSTINA AWASUM BJO KAJ THURESSON, AND CYNTHIA A. DE WIT* Department of Applied Environmental Science (ITM), Stockholm University, SE-106 91 Stockholm, Sweden
Received November 12, 2008. Revised manuscript received February 8, 2009. Accepted February 10, 2009.
Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are globally distributed, persistent, toxic, and are found in human blood and serum. Exposure pathways are not well characterized. To better understand indoor dust ingestion as a potential pathway for human exposure, we determined the concentrations of these compounds in dust collected from 10 houses, 38 apartments, 10 day care centers, 10 offices, and 5 cars. Samples were prepared using a rapid extraction and cleanup method and analyzed using LC-MS/MS. PFOS and PFOA were found in dust samples from all microenvironments and their concentrations were significantly positively correlated to each other. Highest median concentrations were seen in offices (PFOS: 110 ng/g dry weight) and apartments (PFOA: 93 ng/g dw). Adult and toddler dust ingestion exposures were estimated and compared to dietary exposure data from Canada and Spain. Results show that diet is the most important exposure route, but in a worst case scenario, dust ingestion may also be significant.
Introduction Perfluoroalkyl compounds (PFCs) are chemicals that have been used in the production of a wide variety of consumer and industrial products for more than 50 years (1). Because of their widespread use and high persistence, they have been found to be globally distributed in both environmental and biological media. These compounds have been detected in indoor and outdoor air (2, 3) house dust (4), drinking water (5), food (6), and human blood and breast milk (7). PFOS and PFOA are the most commonly studied PFCs and have received wide attention because they are extremely persistent and bioaccumulate in the environment (8). PFOS and PFOA have been found to exhibit acute and subcronic toxicity in the liver (9) and developmental toxicity. (10) They are potent peroxisome proliferators (11), inhibit gap junction intercellular communication (12), and are tumor promoters (13). PFCs have been used in a wide range of consumer products that are found primarily in the indoor environment. Major fields of application include surfactants, surface protection (e.g., for textiles, carpets, and upholstery), paper treatment (e.g., for food packages), and lubricants (14) Although the pathways of human exposure to PFCs remain unclear, some suggested pathways include direct skin contact with consumer products, diet and drinking water, and inhalation of indoor and outdoor air (15). Previous studies * Corresponding author phone: +46 8 674 7180; fax: +46 8 674 7637; e-mail:
[email protected]. 2276
9
ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 43, NO. 7, 2009
have reported that dust is a depot for PCBs and PBDEs, representing a potential source of exposure to these compounds in the indoor environment (16). This may also be the case for PFCs as household dust samples from Japan, Canada, and the United States have been found to contain measurable amounts of PFOS and PFOA (4, 17, 18). Ingestion of house dust may therefore be a significant potential pathway for human exposure to the PFCs. There are no data for PFC concentrations in dust in Sweden. In this study, PFOS and PFOA concentrations in indoor dust collected from day care centers, offices, houses, apartments, and cars from Stockholm, Sweden, were determined. The data obtained from these measurements were used to estimate the daily intake of PFOS and PFOA through dust ingestion for both adults and toddlers (0-2 years). Information gathered using questionnaires was used to determine possible relationships with building characteristics and/or room contents of potential emission sources.
Materials and Methods Standards, Reagents, and Materials. 1,2,3,4-13C4-perfluorooctanoic acid (13C4-PFOA, Wellington Laboratories Inc., Guelph, Ontario, Canada) and 18O2-PFOS (99% HPLC-clean, 3M Company, St. Paul, MN) were used as surrogate standards. As injection standard, 3,5-bis (trifluoromethyl) phenyl acetic acid (ABCR, Karlsruhe, Germany) was used. Standard reference material (SRM 2585, house dust) was obtained from the National Institute of Standards and Technology (Technology Administration, U.S. Department of Commerce, Gaithersburg, MD). Methanol, HPLC grade (Hipersolv) was obtained from WWR International (Leicester, U.K.) and graphitized carbon (Supelclean ENVI-Carb, 120/400) used for cleanup was a product of Supelco (Sigma-Aldrich, Stockholm, Sweden). Polypropylene centrifuge tubes (PP-tubes, 13 mL) were from Sarstedt (Nu ¨ mbrecht, Germany), and cleanup was performed using a syringe (DB Discardit II, Becton and Dickinson S.A., Spain) and 0.45 µm GHP (GHP Acrodisc 13 mm) syringe filters (Pall Life Sciences, Ann Arbor, MI). Dust Sampling. Dust samples were collected during 2006/ 2007 from different microenvironments in Stockholm City, Sweden: living rooms of 10 single detached houses and 3-4 apartments each from 10 different buildings, play rooms from 10 individual day care centers, 10 offices from different buildings, and 5 new cars (4 makes). Dust samples were collected on preweighed cellulose filters in styrene-acrylonitrile holders inserted in a polypropylene nozzle (Krim. Teknisk Materiel AB, Bålsta, Sweden) (19) attached to the intake nozzle of an industrial strength vacuum cleaner (Alto AERO 840). Sampling was done from surfaces at least one meter above the floor, such as on bookshelves, moldings, counters and lampshades in order to eliminate dirt, gravel, and sand. Occupants were asked to fill in a questionnaire regarding construction year; floor area; number of electronic items such as TVs, computers, and video recorders; type of flooring; floor covering; furniture including type of cushioning and covering; presence of textiles, water repellent clothing, Teflon cookware, etc., and when these were acquired. For day care centers, offices and apartment buildings, some of this information was obtained from the building owners. For cars, plastic surfaces were vacuumed first, but as little dust had accumulated there, seat covers were also vacuumed. Before dust sampling, the lid of the styrene-acrylonitrile filter holders was removed and after sampling, the lid was replaced and the holder sealed in a plastic bag and stored at -20 °C. Before extraction, filter holders containing filters were allowed to equilibrate at room temperature for 24 h before being 10.1021/es803201a CCC: $40.75
2009 American Chemical Society
Published on Web 03/05/2009
FIGURE 1. Box and whiskers plots showing the distribution of PFOS and PFOA in dust from houses, day care centers, cars, offices, and apartments. Boxes show 25th and 75th percentiles and median. Whiskers show the lowest and highest concentrations.
FIGURE 2. Correlation between log-transformed PFOS and PFOA concentrations in all dust samples. weighed to determine the amount of dust to be used for extraction. For the houses, offices, and day care centers, dust was carefully scraped off the filter and weighed into four aliquots of which one was placed in a PP tube. For the cars, dust amounts were so small that they could not be scraped off, so the filters were cut in small pieces and placed in PP tubes. For the apartments, the dust on the entire filter was scraped carefully off, divided into four weighed aliquots and the filter cut into four equal sized-pieces. One aliquot and one filter were placed in a PP tube for PFC analysis. The other dust aliquots were used for the analysis of other compounds. Extraction and Cleanup. Extraction and clean up was based on the method described by Powley et al. (20) with some modifications. Surrogate standards (50 µL each of 13C4PFOA (201.4 pg/µL) and 18O2-PFOS (200 pg/µL)) were added to the dust sample (2-170 mg) in a 13 mL PP tube, together with approximately 10 mg of Envi-Carb (incorporated cleanup). Methanol (5 mL) was added and the tube vortexed for 10 s before extraction by ultrasound for 10 min. After extraction, samples were centrifuged for 10 min at 3600 rpm. The supernatant was transferred to a new PP tube. The extraction procedure was repeated once, the extracts combined, and the volume reduced to 500 µL under a gentle stream of nitrogen at 30 °C. Five hundred microliters of a 4 mM ammonium acetate buffer in water was added and the
buffer/extract mixture was filtered through the GHP syringe filter into a PP-autosampler vial, prespiked with 50 µL injection standard ((3,5-bis(trifluoromethyl) phenyl acetic acid in methanol, 200 pg/µL). The autosample vial was vortexed before the LC/MS analysis. Instrumental Analysis. Dust samples were analyzed for PFOS and PFOA using a high-performance liquid chromatograph (Waters Alliance 2695, Waters Corp., Milford, MA) coupled to a tandem mass spectrometer (Micromass Quatro II, Altrincham, U.K) (HPLC-MS/MS) operated in electrospray negative ionization mode. The HPLC-MS/MS was supplied with a built-in autosampler used for sample injection, and controlled by Masslynx 3.2 software. Sample extracts (25 µL) were injected onto a C18-precolumn (Chrom Tech, 10 × 2 mm, 5 µm Hyperpurity) followed by an Ace C18-column (ACT, Aberdeen 15 × 2.1 mm, 3 µm particles). The flow rate was 0.2 mL/min, and the mobile phase consisted of 2 mM ammonium acetate in methanol/water (40:60 v/v) (A) and 2 mM ammonium acetate in methanol/water (95:5 v/v) (B). Prior to analysis, the column was preconditioned for 2 min with 100% B. The elution started by a 6 min linear gradient to 80% B, which was kept for 10 min before returning to 100% A. The run time was 18 min. PFOS and PFOA were measured using MS/MS in selected reaction monitoring (SRM) mode, with argon as collision gas. Ion transitions monitored were m/z 499 > 80 for PFOS, m/z 413 > 369 for VOL. 43, NO. 7, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
9
2277
TABLE 1. Comparison of Median (range) PFOS and PFOA Concentrations (ng/g dry weight) from Different Microenvironments Worldwide country
microenvironment
n
PFOS median (range)
PFOA median (range)
ref
Japan Canada United States Sweden Sweden United Kingdom Sweden Sweden Sweden
homes homes homes & daycare centers houses apartments primary & nursery classrooms daycare centers offices cars
16 67 102 + 10 10 38
25 (11-2500) 38 (2-5700) 201 (9-12100) 39 (15-120) 85 (8a-1100) 1200 (85-3700) 31 (23-65) 110 (29-490) 12 (8a-33)
165 (70-3700) 20 (1-1230) 142 (10 1960) 54 (15-98) 93 (17-850) 220 (42-640) 41 (31-110) 70 (14-510) 33 (12-96)
(4) (17) (18) this study this study (28) this study this study this study
a
10 10 5
LOQ/2.
TABLE 2. Total Differentiated Intake Estimates for PFOS and PFOA in ng/day for Adults and Toddlers Calculated Using Median or Maximum Dust Concentrations in the Different Microenvironments (Tables S2 and S3 in the Supporting Information) Multiplied by the Fraction of Time Estimated to Be Spent in These Microenvironments and Summed (see text); For Purposes of Simplification, the Values Used for Homes Were Calculated by Averaging the Exposure from Houses and Apartments for the Different Scenarios mean dust ingestion scenario
high dust ingestion scenario
adult toddler adult toddler adult toddler adult toddler median median max max median median max max PFOS PFOA sum PFCs
0.3 0.3 0.6
3 3 6
2 2 4
24 21 45
7 7 14
10 11 21
53 32 85
88 75 163
PFOA, m/z 503 > 84 for 18O2-PFOS, and 417 > 372 for 13 C4-PFOA. Optimized parameters applied were capillary voltage, 2.5 kV; source temperature, 120 °C; drying and nebulizer nitrogen gas flows, 400 and 20 L/h, respectively; and argon pressure, 6.1 × 10-4 mbar. QA/QC. Quantification was based on the internal standard method. The ratio of the peak area of the analyte to that of the labeled internal standard was calculated using a onepoint calibration after determining the linearity of PFOS and PFOA using standard solutions over a concentration range from 10 to 2000 ng/g. The linearity of the calibration curves was satisfactory with correlation coefficients greater than 0.99 for each analyte. The labeled internal standards were added before the extraction and used for the identification of PFOS and PFOA. An injection standard was used to monitor the recovery of the internal standard. For each batch of 21 dust samples analyzed, 3 solvent blanks, and 3 NIST SRM 2585 house dust samples were analyzed in parallel. Blank filters (3 in total) used for the sampling were also analyzed. During the LC-MS/MS analysis, solvent injections were done regularly to monitor possible instrumental background/carryover effects. Multiple isomers of PFOS were all integrated and designated PFOS. The limits of detection (LOD) were set to 3 times the average solvent blank values. The LOQ value was set as the lowest quantified sample above the LOD, giving rise to LOQ values of 12 ng/g for PFOS and 12 ng/g for PFOA. Statistical Analyses. For statistical analyses, all concentration data were first log-transformed because of the skewed nature of the data. In order to include all samples in the statistical analysis, those with concentrations below the limit of quantitation (LOQ) were assigned a value of LOQ/2. For correlation analyses (Pearson’s correlation), values below the LOQ were removed. 2278
9
ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 43, NO. 7, 2009
Results and Discussion To determine method precision, we spiked nine replicate dust samples with 18O2-PFOS and 13C4-PFOA and analyzed them. The mean ((standard deviation) recovery calculated from these dust samples was 74 ((5%) for PFOS and 78 ((4%) for PFOA. The method recovery was 88 ( 14% for PFOS and 87 ( 18% for PFOA (mean ( standard deviation (SD), n ) 73). To our knowledge, there is currently no indoor dust standard reference material available with certified or even indicative concentrations of PFOS or PFOA. To include a homogeneous reference dust as quality control, a house dust with certified values for many other halogenated compounds (NIST SRM 2585) was used (21). The average concentrations measured in the NIST SRM 2585 dust were 1990 ( 78 ng/g for PFOS and 673 ( 26 ng/g for PFOA (n ) 19) (see Figure S1 in the Supporting Information). The reported concentrations were corrected for the solvent blanks (typically 0.1-0.5 ng PFOS and 0.02-0.1 ng PFOA). PFOS and PFOA in unused filters were not above the solvent blank concentrations. Comparisons between Microenvironments. Both PFOS and PFOA were found in dust samples from houses, day care centers, and offices. Among the samples from 38 apartments, PFOS and PFOA were detected in 79 and 100% of the samples, respectively. PFOS was detected in 3 out of 5 car samples, whereas PFOA was detected in all of the car samples. PFOA concentrations were higher than those of PFOS in 60% of all the samples. The concentrations of both PFOS and PFOA from all the microenvironments were not normally distributed; they were skewed toward higher concentrations (Figure 1). Although offices had the highest median PFOS concentrations, the highest individual concentrations were found in apartments (Figure 1). The highest individual PFOA concentrations were also found in some apartments (Figure 1). The highest variation for both compounds is seen in apartments. Houses and daycare centers have much less variability in concentrations. A statistical summary (range, median, and mean) is presented in Table S1 of the Supporting Information. The median concentrations in the different microenvironments are within 1 order of magnitude of each other (see Figure S2 in the Supporting Information). The highest median PFOS concentrations were seen in offices (110 ng/g dw); similar but lower concentrations were seen in apartments (85 ng/g dw), houses (39 ng/g dw), and day care centers (31 ng/g dw); and lowest concentrations were seen in cars (12 ng/g dw). For PFOA, the concentrations were more similar between different microenvironments, with highest median concentrations found in apartments (93 ng/g dw) and offices (70 ng/g dw). Offices had higher median PFOS than PFOA concentrations, whereas the opposite was found for the other microenvironments. Correlation between PFOS and PFOA. A statistically significant correlation (p < 0.05) was found between PFOS
TABLE 3. Summary of Estimates of Exposure (ng/day) for Adults and Toddlers to PFOS via Dietary Intake (Spanish estimate (24)) and Mean and High Dust Ingestion and the Relative Significance (%) of Each Pathway. Estimates Have Been Calculated Separately for Dust Exposure When Living in Houses or Apartments adult
toddler
PFOS
median house
median apt
max house
max apt
median house
median apt
max house
max apt
food dust ingestion (mean) dust ingestion (high) ∑mean dusta ∑high dustb
63 0.3 5 63 68
63 0.4 9 63 71
63 0.8 19 63 82
63 4 87 66 149
35 2 7 37 42
35 4 13 39 48
35 5 20 40 55
35 43 157 78 192
95 5
90 10
87 13
45 55
83 17
73 27
64 36
18 82
% contribution mean dust ingestion food dust
100 0.4
food dust
92 8
99 0.6
99 1.2
95 5
high dust ingestion 88 12
77 23
42 58
a ∑mean dust is the sum of PFOS ingested from food and from mean dust ingestion. ingested from food and from high dust ingestion.
and PFOA dust concentrations (log-transformed data) when data from all microenvironments were included (Figure 2). Statistically significant correlations were also seen when dust samples were compared for houses, apartments, and offices separately. No statistically significant correlation was seen when dust samples from only daycare centers were compared. Previous studies of PFOS and PFOA in dust have also found statistically significant correlations between these compounds (4, 17, 18). Because of the limited number of dust samples from cars, it was not possible to carry out a correlation analysis. The significant correlation between PFOS and PFOA suggests that these PFCs may be from a common source in the different microenvironments or may originate from the same precursor compound. Comparisons to Published Data. In Table 1, the median concentrations of PFOS and PFOA from this study are compared to literature data. The PFOS concentrations in Swedish homes were similar (houses, 39 ng/g dw) or higher (apartments, 85 ng/g dw) than those from Japanese and Canadian homes, but five times lower than those of the United States. The PFOA concentrations in Swedish homes were lower (houses 54 ng/g dw, apartments 93 ng/g dw) than in dust from American and Japanese homes, but higher than those in Canadian homes. Both PFOS (31 ng/g dw) and PFOA (41 ng/g dw) concentrations in dust from Swedish daycare centers were lower than those from the United Kingdom (Table 1). In Swedish office environments, the PFOS (110 ng/g dw) and PFOA concentrations (70 ng/g dw) were lower than in U.K. classrooms. There are currently no published data for PFOS or PFOA in dust from cars with which to compare our results. Estimated Human Exposure to PFCs. Measured concentrations from the different microenvironments were used to estimate the exposure of adults and toddlers (6-24 months of age) to PFOS and PFOA from dust ingestion. We have assumed 100% absorption of PFC intake, mean adult and toddler dust ingestion rates of 4.16 and 100 mg/day, and high dust ingestion rates for adults and toddlers of 55 and 200 mg/day (22, 23). Using these dust ingestion rates and the median and maximum PFOS and PFOA concentrations found, we have estimated plausible dust ingestion scenarios of PFOS and PFOA associated with each individual microenvironment, assuming 100% exposure in each microenvironment separately (see Tables S2 and S3 in the Supporting Information).
b
∑high dust is the sum of PFOS
However, PFC ingestion will be proportional to the fraction of time spent in the different microenvironments per day. The fractions of time spent in the various microenvironments in this study are not known so estimates from a study in the United Kingdom were used (16). Toddlers are assumed to spend approximately as much time in daycare centers as adults spend in an office. The average time spent in homes (houses or apartments), offices (adults) or daycare centers (toddlers), cars, and outdoors was estimated as 68, 22, 4, and 5%, respectively. On the basis of these estimates, the major exposure was found to occur in people’s homes (74% for mean and 75% for high dust ingestion scenarios). In Table 2, the differentiated total estimates for adult and toddler exposure to PFOS and PFOA via dust ingestion are summarized. The estimated intakes of PFOS and PFOA are similar (Table 2). Both adults and toddlers are exposed to both PFCs from indoor environments. Toddlers have higher intakes from dust ingestion than adults in all scenarios. The majority of the population probably has a lower exposure to PFCs via dust ingestion, but the results using the worst case scenario indicate that there may be a small percentage of the general population that has a much higher exposure. Comparison of Dust Ingestion and Dietary Intake. There are currently no Swedish estimates for dietary intake of PFCs. The estimated dietary intake of PFOS for adults in Spain was measured to be 63 ng/day (no estimate could be made for PFOA) (24) In a Canadian study, this was 110 ng/day for PFOS and 70 ng/day for PFOA (6). The Spanish dietary estimate is compared with dust ingestion data from this study in Table 3 to provide a preliminary indication of the relative significance of dust ingestion and diet to overall human exposure to PFOS for adults and toddlers. Dietary intake for toddlers has been estimated to be 57% of adult intake (25); this number was used in the calculations. In Table 3, the estimated PFOS intake for adults and toddlers and the significance of exposure via dust ingestion relative to diet are summarized. Diet is the major exposure pathway in the mean dust ingestion scenario (up to 99.6% for adults and 95% for toddlers). However, in the worstcase scenario (high dust ingestion, maximum dust concentrations), dust ingestion could be a major route of exposure to PFOS (58% for adults and 82% for toddlers), particularly for toddlers. In Table S4 of the Supporting Information, the results of comparing dietary intake VOL. 43, NO. 7, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
9
2279
estimates for PFOS from the Canadian study (6) with the dust ingestion estimates of the present study are presented for comparison and show similar results. As the dietary intake estimate for PFOS is higher, however, the dust ingestion estimates in the worst-case scenario are somewhat lower (up to 44% for adults, 71% for toddlers). Similar results were found using the Canadian dietary intake estimates of PFOA (6) (see Table S5 in the Supporting Information). Dietary intake is again the major exposure pathway for PFOA in the mean dust ingestion scenario (up to 100% for adults, and 94% for toddlers), but in the worstcase scenario, dust ingestion becomes more important (40% for adults, 77% for toddlers). These estimates of the contributions to total intake of PFOS and PFOA from dust ingestion are limited by the uncertainty in dust ingestion rates and methods for measuring dust ingestion. To determine which of the exposure scenarios is the most relevant, studies of body burdens of PFOS and PFOA in adults and in toddlers in conjunction with dust sampling are needed as well as studies of the dietary intake of these PFCs from foodstuffs in Sweden. Sources of PFOS and PFOA. On the basis of information provided from questionnaires, relationships between the presence and number of household items that could be potential emission sources of PFCs and concentrations found in dust were studied. No correlations were found. However, one major observation was that offices at a book publisher, a major newspaper publisher, and at work places where large volumes of papers were present had the highest PFOS and PFOA concentrations. Though PFOS is not extensively used on its own, it is an essential degradation product from diverse fluoropolymers that have been used as surfactants, water, and dirt repellents, electrostatic charge and friction control agents for mixtures used in coatings applied to papers and printing plates (26). PFOA has been used as a nonreactive polymerization aid in the production of fluorotelomer alcohol (FTOH) polymers. FTOH derived polymers have been used to impregnate paper/cardboards to make them grease and water repellant (27). To conclude, this study shows that PFOS and PFOA are present in dust from all sampled microenvironment and that dust ingestion could be a significant exposure route to toddlers.
Acknowledgments We thank Karin Syversen, Thorvald Staaf, and Caroline Berg (Stockholm University) for collecting the air and dust samples; Gunnel Emenius, Rebecca Thore´n, and Maria Zetterstedt (Department of Occupational and Environmental Medicine, Karolinska Hospital) for organizing the logistics of sampling apartments; Urs Berger and Karin Nordstro¨m (Stockholm University) for help with the PFC analyses. We also thank Ulla Sellstro¨m for comments on the manuscript. This study was supported financially by the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS) and the Stockholm City Environmental Agency.
Supporting Information Available Two figures showing quality control charts for PFOS and PFOA in the NIST SRM 2585 dust sample over time and median concentrations of both compounds in the different microenvironments; five tables presenting summary statistics of PFOS and PFOA concentrations in dust from different microenvironments, exposure estimates from dust ingestion in adults and toddlers for PFOS and PFOA, respectively, and comparison of dust exposure to dietary 2280
9
ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 43, NO. 7, 2009
exposure for PFOS and PFOA (PDF). This material is available free of charge via the Internet at http://pubs.acs.org.
Literature Cited (1) Olsen, G. W.; Huang, H. Y.; Helzlsouer, K. J.; Hansen, K. J.; Butenhoff, J. L.; Mandel, J. H. Historical comparison of perfluorooctanesulfonate, perfluorooctanoate, and other fluorochemicals in human blood. Environ. Health Perspect. 2005, 113, 539–545. (2) Shoeib, M.; Harner, T.; Ikonomou, M.; Kannan, K. Indoor and Outdoor Air Concentrations and Phase Partitioning of Perfluoroalkyl Sulfonamides and Polybrominated Diphenyl Ethers. Environ. Sci. Technol. 2004, 38, 1313–1320. (3) Barber, J. L.; Berger, U.; Chaemfa, C.; Huber, S.; Jahnke, A.; Temme, C.; Jones, K. C. Analysis of per and polyfluorinated alkyl substances in air samples from northwest Europe. J. Environ. Monit. 2007, 9, 530–541. (4) Moriwaki, H.; Takata, Y.; Arakawa, R. Concentrations of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in vacuum cleaner dust collected in Japanese homes. J. Environ. Monit. 2003, 5, 753–757. (5) Skutlarek, D.; Exner, M.; Farber, H. Perfluorinated surfactants in surface and drinking water. Environ. Sci. and Poll. Res. 2006, 13, 299–307. (6) Tittlemier, S. A.; Pepper, K.; Seymour, C.; Moisey, J.; Bronson, R.; Cao, X. L.; Dabeka, R. W. Dietary exposure of Canadians to perfluorinated carboxylates and perfluorooctane sulfonate via consumption of meat, fish, fast foods, and food items prepared in their packaging. J.Agric. Food Chem. 2007, 55, 3203–3210. (7) Ka¨rrman, A.; Ericson, I.; van Bavel, B.; Darnerud, P. O.; Aune, M.; Glynn, A.; Lignell, S.; Lindstro¨m, G. Exposure of perfluorinated chemicals through lactation: Levels of matched human milk and serum and a temporal trend, 1996-2004, in Sweden. Environ. Health Perspect. 2007, 115, 226–230. (8) Martin, J. W.; Mabury, S. A.; Solomon, K. R.; Muir, D. C. G. Dietary accumulation of perfluorinated acids in juvenile rainbow trout (Oncorhynchus mykiss). Environ. Toxicol. Chem. 2003, 22, 189–195. (9) Lau, C.; Anitole, K.; Hodes, C.; Lai, D.; Pfahles-Hutchens, A.; Seed, J. Perfluoroalkyl acids: A review of monitoring and toxicological findings. Toxicol. Sci. 2007, 99, 366–394. (10) Lau, C.; Butenhoff, J. L.; Rogers, J. M. The developmental toxicity of perfluoroalkyl acids and their derivatives. Toxicol. Appl. Pharmacol. 2004, 99, 366–394. (11) Berthiaume, J.; Wallace, K. B. Perfluorooctanoate, perfluorooctanesulfonate, and N-ethyl perfluorooctanesulfonamido ethanol; peroxisome proliferation and mitochondria biogenesis. Toxicol. Lett. 2002, 129, 23–32. (12) Upham, B. L.; Deocampo, N. D.; Wurl, B.; Trosko, J. E. Inhibition of gap junctional intercellular communication by perfluorinated fatty acids is dependent on the chain length of the fluorinated tail. Int. J. Cancer 1998, 78, 491–495. (13) Beigel, L. B.; Hurtt, M. E.; Frame, S. R.; O’Connor, J. C.; Cook, J. C. Mechanisms of extrahepatic tumor induction by peroxisome proliferators in male CD rats. Toxicol. Sci. 2001, 60, 4455. (14) Prevedouros, K.; Cousins, I. T.; Buck, R. C.; Korzeniowski, S. H. Sources, fate, and transport of perfluorocarboxylates. Environ. Sci. Technol. 2006, 40, 32–44. (15) Vestergren, R.; Cousins, I. T.; Trudel, D.; Wormuth, M.; Scheringer, M. Estimating the contribution of precursor compounds in consumer exposure to PFOS and PFOA. Chemosphere 2008, 73, 1617–1624. (16) Harrad, S.; Hazrati, S.; Ibarra, C. Concentrations of polychlorinated biphenyls in indoor air and polybrominated diphenyl ethers in indoor air and dust in Birmingham, United Kingdom: Implications for human exposure. Environ. Sci. Technol. 2006, 40, 4633–4638. (17) Kubwabo, C.; Stewart, B.; Zhu, J. P.; Marro, L. Occurrence of perfluorosulfonates and other perfluorochemicals in dust from selected homes in the city of Ottawa, Canada. J. Environ. Monit. 2005, 7, 1074–1078. (18) Strynar, M. J.; Lindstrom, A. B. Perfluorinated compounds in house dust from Ohio and North Carolina, USA. Environ. Sci. Technol. 2008, 42, 3751–3756. (19) Bornehag, C. G.; Lundgren, B.; Weschler, C. J.; Sigsgaard, T.; Hagerhed-Engman, L.; Sundell, J. Phthalates in indoor dust and their association with building characteristics. Environ. Health Perspect. 2005, 113, 1399–1404.
(20) Powley, C. R.; George, S. W.; Ryan, T. W.; Buck, R. C. Matrix effect-free analytical methods for determination of perfluorinated carboxylic acids in environmental matrixes. Anal. Chem. 2005, 77, 6353–6358. (21) Stapleton, H. M.; Harner, T.; Shoeib, M.; Keller, J. M.; Schantz, M. M.; Leigh, S. D.; Wise, S. A. Determination of polybrominated diphenyl ethers in indoor dust standard reference materials. Anal. Bioanal. Chem. 2006, 384, 791–800. (22) U. S. Environmental Protection Agency. Exposure Factors Handbook; EPA/600/P-95/002; EPA: Washington, DC, 1997. (23) U. S. Environmental Protection Agency. Child-Specific Exposure Factors Handbook; EPA/600/P-00/002B; National Center for Environmental Assessment, EPA: Washington, DC, 2002. (24) Ericson, I.; Cid, R.; Nadal, M.; Van Bavel, B.; Lindstro¨m, G.; Domingo, J. Human Exposure to Perfluorinated Chemicals through the Diet: Intake of Perfluorinated Compounds in Foods from the Catalan (Spain) Market. J. Agric. Food Chem. 2008, 56, 1787–1794.
(25) Wilford, B. H.; Shoeib, M.; Harner, T.; Zhu, J. P.; Jones, K. C. Polybrominated diphenyl ethers in indoor dust in Ottawa, Canada: Implications for sources and exposure. Environ. Sci. Technol. 2005, 39, 7027–7035. (26) Department for Environment, Food, and Rural Affairs. Perfluorooctane Sulfonate, Risk Reduction Strategy, and Analysis of Advantages and Drawbacks; DEFRA: London, 2004; available at http://www.defra.gov.uk/environment/chemicals/pdf/pfosriskstrategy.pdf. (27) GreenPeace. Uses of Perfluorinated Substances;Greenpeace Research Laboratories Technical Note 06/2006; Greenpeace Research Laboratories: Devon, U.K., 2006. (28) Goosy, E.; Abou-Elwafa, A. M.; Harrad, S. Dust from Primary school and Nursery classrooms in the UK: Its significance as a pathway to exposure to PFOS, PFOA, HBCDs and TBBP-A. Organohalogen Compd. 2008, 70, 855–858.
ES803201A
VOL. 43, NO. 7, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
9
2281
