National Screening Study on 10 Perfluorinated Compounds in Raw and Treated Tap Water in France

Transcription

1 Arch Environ Contam Toxicol (2012) 63:1 12 DOI /s National Screening Study on 10 Perfluorinated Compounds in Raw and Treated Tap Water in France Virginie Boiteux Xavier Dauchy Christophe Rosin Jean-François Munoz Received: 2 November 2011 / Accepted: 13 February 2012 / Published online: 9 March 2012 Ó Springer Science+Business Media, LLC 2012 Abstract The occurrence of seven perfluoroalkyl carboxylates (PFCAs) and three perfluoroalkyl sulfonates (PFASs) was studied in raw- and treated-water samples from public water systems. Two sampling campaigns were performed during the summer of 2009 and in June Sampling was equally distributed across the 100 French departments. In total, 331 raw-water samples and 110 treated-water samples were analyzed during this study, representing approximately 20% of the national water supply flow. Concentrations of perfluorinated compounds (PFCs) were determined using automated solid-phase extraction and liquid chromatography tandem mass spectrometry. In raw-water samples, the highest individual PFC concentration was 139 ng/l for perfluorohexanoic acid (PFHxA). The sum of all of the determined components was [100 ng/l at three sampling points (199, 117, and 115 ng/l). Of the investigated PFCs, perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA), and PFHxA predominated (detected in 27%, 13%, 11%, and 7% of samples, respectively). Geographical variability was observed, with departments crossed by major rivers or with high population densities being more affected by PFC contamination. Compared with raw water, short-chain PFCAs, but not PFASs, were found in higher abundance in treated water. This difference suggests a relative effectiveness of certain water treatments for the elimination of PFASs but also Electronic supplementary material The online version of this article (doi: /s ) contains supplementary material, which is available to authorized users. V. Boiteux X. Dauchy (&) C. Rosin J.-F. Munoz Water Chemistry Department, Nancy Laboratory for Hydrology, ANSES, Nancy, France xavier.dauchy@anses.fr a possible degradation of PFCA precursors by watertreatment processes. Our investigations did not show any heavily contaminated sites. In treated-water samples, the highest individual PFC concentration was 125 ng/l for PFHxA. The sum of all of the determined components was [100 ng/l at one sampling point (156 ng/l). The values observed for PFOS and PFOA in drinking water were not greater than the health-based drinking-water concentration protectives for lifetime exposure that have been defined for other countries. Perfluorinated compounds (PFCs) include a large number of chemicals that have been produced and used worldwide since the 1950s (Prevedouros et al. 2006). They are characterized by their carbon chain of varying length, in which all or most of the carbon hydrogen bonds are replaced by carbon fluorine (C F) bonds (see Table 1A in Supplemental Material for a list of the main PFCs). The C F bond is thermodynamically one of the strongest known (488 kj/ mol) and gives PFCs unique physical and chemical properties. The C F tail makes PFCs extremely resistant to heat and chemical degradation, and they are good repellents to oils and grease in addition to water. The C F chain length influences the surfactant properties, with the C 8 F 17 chain being optimal according to industry scientists. Their ability to repel both oil and water makes PFCs suitable as protective coatings for carpets, textiles, and leather, as well as grease repellents for paper, e.g., for popcorn bags and food-wrapper coatings. However, PFCs are also added to polishes, paints, adhesives, and waxes to make them easier to apply. They are also used in firefighting foams, electronics, semiconductors, insecticides, cleaners, and space materials (Giesy and Kannan 2002; Moody and Field 2000; Renner 2001, 2007).

2 2 Arch Environ Contam Toxicol (2012) 63:1 12 Owing to their dual oleophobic and hydrophobic properties, the environmental behavior of fluorinated chemicals is probably different from that of most organic compounds (Rayne and Forest 2009). Due to their widespread applications and stability, they are omnipresent in the environment and have been found at different levels of concentration in water (Ahrens 2011; Mak et al. 2009; Murakami et al. 2009; Plumlee et al. 2008; Schultz et al. 2004; Taniyasu et al. 2005), wastewater-treatment plant sludge (D Eon et al. 2009), precipitation (Kwok et al. 2010; Scott et al. 2006), wildlife (Kelly et al. 2009; Yeung et al. 2009), and in both indoor and outdoor air (Shoeib et al. 2004; Stock et al. 2004). The general population is exposed to PFCs as indicated by PFC presence in blood (Calafat et al. 2007; Olsen et al. 2008). Several exposure pathways e.g., ingestion of food that has come into in contact with articles treated with fluorinated polymers (D Eon and Mabury 2007), ingestion of contaminated water, and inhalation of PFCs, with relative contributions varying with lifestyle and location are probably involved in human blood contamination. In the environment, some PFCs can degrade through biological or nonbiological processes into perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFASs), which are the two most widely known groups of PFCs, and final degradation products of a variety of PFC precursors, including fluorotelomer alcohols (FTOHs), fluorotelomer sulfonates, perfluorooctane sulfonamidoethanols, and perfluorooctane sulfonamide (Lee et al. 2010; Rhoads et al. 2008; Washington et al. 2009). PFCAs and PFASs do not break down in the environment and thus persist indefinitely. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are the most commonly investigated and detected compounds. Environmental presence of PFASs and PFCAs results mainly from two pathways: direct release from their salts, which are used as processing aids in fluoropolymer manufacturing (Prevedouros et al. 2006), and indirect release through the degradation of fluorotelomer-based polymers or unbound residual precursors, whose the significant presence has been reported in a suite of consumer and industrial products (Dinglasan-Panlilio and Mabury 2006; Washington et al. 2009). PFCs have been released into air, water, and soil from various manufacturing and use point sources. Discharges from wastewater-treatment plants, consumer use, and disposal (landfill and incineration) are considered to contribute more diffusively to the global spread of PFCs (Kunacheva et al. 2011; Shivakoti et al. 2010). Several serious cases of drinking water contaminated by emissions from industrial facilities have been described (Emmett et al. 2006; Skutlarek et al. 2006; Steenland et al. 2009). Human-biomonitoring studies have shown that increased PFC exposure by way of drinking water leads to greater PFC levels in plasma compared with nonexposed groups (Hölzer et al. 2008; Wilhelm et al. 2008). Bioaccumulation of PFCs in wildlife and humans is a concern because increased exposure to these compounds can affect the liver, lipid metabolism, the immune system, reproduction, and development (Giesy et al. 2010; Lau et al. 2007; Steenland et al. 2010). The goal of this study was to evaluate the occurrence of 10 PFCs (PFOA, PFOS, perfluorobutanoic acid [PFBA], perfluorobutane sulfonate [PFBS], perfluorohexane sulfonate [PFHxS], perfluorohexanoic acid [PFHxA], perfluoropentanoic acid [PFPeA], perfluoroheptanoic acid [PFHpA], perfluorononanoic acid [PFNA], and perfluorodecanoic acid [PFDA]) in raw and treated water. We collected and analyzed 331 samples of surface water and groundwater used for public water systems and 110 samples of treated water. These samples were taken from 262 sites that together represent approximately 20% of the national water supply flow. To our knowledge, the only national screening campaign on perfluorinated substances (with a comprehensive nationwide sampling scheme and a large number of samples) has been conducted in Sweden (Woldegiorgis et al. 2006). With 21 water samples, the Swedish sampling strategy was designed around the possible sources of PFCs. Our sampling strategy aimed to investigate all French departments and to select sites providing significant water flow relative to national production as well as ensure a reasonable number of samples. France is divided into 96 metropolitan departments and four overseas departments. Each is run by its own local council, which has its headquarters in the principal town. The 10 PFCs were selected according to their occurrence in water as reported in other publications (Mak et al. 2009; Nakayama et al. 2010; Skutlarek et al. 2006). Additional goals were to observe the distribution of the composition profile in groundwater and surface-water samples and to evaluate the potential PFC exposure of a significant part of the French population due to water consumption. Materials and Methods Chemicals and Standards All chemicals were of the purest quality available. PFCs and 13 C-labeled internal standards were purchased from Wellington Laboratories (Guelph, Ontario, Canada). All standards had purities C98%. PFC solutions were prepared with a mix of methanol and liquid chromatographymass spectrometry (LC MS) grade water (30/70 v/v). Reagent-grade formic acid and ammonium acetate were obtained from Merck (Germany). LC MS grade water and

3 Arch Environ Contam Toxicol (2012) 63: methanol were obtained from Biosolve (Holland). A reagent-grade ammonia solution was purchased from Carlo-Erba (France). Sample Collection and Preparation Sample collection was performed by personnel from the French Ministry of Health during two sampling campaigns. During the first sampling campaign, both raw- and treatedwater samples were collected from July to September All 100 French departments were included in this study. For each department, two sample sites were monitored: (1) the drinking-water source producing the greatest flow in the department and (2) a randomly selected drinking-water source. Raw- and treated-water samples were systematically collected. Sixty-six additional samples of raw water only were included because these sites were possibly affected by releases due to industrial or commercial activities, thus increasing the likelihood of detection of PFCs. Each department was permitted to select no more than one additional sample. During this first sampling campaign, we analyzed only the treated-water samples, which had PFC levels greater than the limit of quantification (LOQ) in raw water. In total, 262 raw-water samples and 41 treated-water samples were analyzed. A second sampling campaign was conducted in June 2010 during which 69 raw-water and 69 treated-water samples were collected and analyzed. This sampling campaign focused on the sites from the first sampling campaign that had PFC levels greater than the LOQ. The objectives were to confirm PFC presence in the water and to determine if there were any temporal trends between the two sampling campaigns. In total, 331 raw-water and 110 treated-water samples were analyzed during this study. All water samples were collected in high-density polyethylene bottles, shipped on cold packs in polystyrene boxes, and arrived at our laboratory within 24 to 48 h. The raw-water samples were stored at 4 C before analysis after acidification by formic acid (3 \ph \4) to prevent bacterial activity. In most cases, samples were extracted within 15 days of collection. Sodium thiosulphate was added to treated-water samples to neutralize free residual chlorine. Chemical Analysis Water samples of 500 ml were used for extractions. No filter was used to eliminate the suspended solids. Solidphase extraction (SPE) cartridges (Oasis Wax 6 cm 3 / 150 mg; Waters, France) were used to extract the perfluorinated alkylated substances. The samples were passed through the cartridges at a flow rate of 4 ml/min. Cartridges were then dried for 20 min with nitrogen. The analytes were eluted from the cartridges with 2 ml of methanol and then with 4 ml of NH 4 OH 0.1% (v/v) in methanol. Offline enrichment was conducted on an automated system (GX-274, Aspec; Gilson, France). Finally, the volume of the solvents was decreased under nitrogen and adjusted to an extracted volume of 200 ll with a 70:30 ratio of water to methanol. The purified SPE eluents were separated and quantified using a TSQ Quantum Ultra liquid chromotographer tandem mass spectrometer (Thermo Scientific, France) operating in negative electrospray ionization mode. The analytical method is described in detail in Supplemental. Quality Control and Assurance Quantification of the individual compounds was performed using 13 C-labeled internal standards. They were added to each water sample and used to check the overall recovery of target chemicals during the analytical procedure. PFOA, PFNA, and PFHxS were quantified using 13 C-labeled PFOA. PFHxA, PFPeA, PFHpA, and PFBS were quantified using 13 C-labeled PFHxA. PFOS, PFDA, and PFBA were quantified using their respective 13 C-labeled homologues. With the use of the appropriate 13 C-labeled compounds, the recoveries were greatly improved and ranged from 60% (PFPeA) to 130% (PFBS) regardless of the water matrix. The LOQ was defined as the smallest concentration of standard that results in a reproducible measurement of peak areas consistent with the calibration curve. This concentration was used as the second point of the calibration curve and was confirmed before each set of determinations. For the method employed here, the LOQ for a 500-mL water sample by LC/MS MS was 4 ng/l for each PFC. Limits of detection (LODs) for the analytes were defined as LOQ/3 (ISO/TS Guidance on analytical quality control for chemical and physicochemical water analysis). Concentrations of target analytes were quantified using calibration curves constructed using mixtures of individual standards. Six different concentrations were analyzed (2, 4, 20, 40, 60, and 80 ng/l), and the quadratic fit of the calibration curves obtained was systematically checked. The compounds were identified by retention time match and their specific multiple reaction monitoring (MRM) transitions. To ensure that quantification was valid throughout the entire analysis, calibration check standards were run during and at the end of analytical runs. For sampling protocols and methodologies, care was taken to avoid sample contact with products, such as Teflon, known to contain PFCs. The absence of contamination was assessed by pouring LC MS grade water into collection bottles and performing the overall analytical procedure. Despite these precautions, PFOA was consistently observed in the analysis of our blanks at concentrations lower than the LOD. Consequently, the PFOA LOD was set at 2 ng/l.

4 4 Arch Environ Contam Toxicol (2012) 63:1 12 The stability of PFCs was investigated before the sampling campaign by a spiking experiment at 40 ng/l during a period of 30 days using surface- and tap-water samples. The spiked samples were stored in the dark and frozen at 20 C. All PFCs were relatively stable during this time period (recoveries ranged from 58% to 128% depending to the compound). It is known (De Silva and Mabury 2006) that some PFCs may have distinct structural isomers (linear and branched). In this study, all PFC concentrations were determined by integrating a single chromatographic peak. This peak was selected based on retention-time match and specific MRM transitions with the individual standard injections. This peak was presumed to be the linear isomer, but branched isomers may have coeluted. According to the mass chromatograms of the water samples that we observed, our chromatographic conditions were able to separate some branched isomers (Supplemental Fig. A4). For linear PFOS isomers, branched isomers were also found in water samples. The peak areas were sometimes equal to those attributed to the linear isomer. Due to possible differences between the electrospray-ionization response of the isomers and the linear standards, these peaks were not quantified. The occurrence of branched isomers was attributed to the manufacturing process, with electrochemical fluorination yielding 30% branched PFOS isomers, whereas telomerization produces [98% of linear PFOS isomers (Martin et al. 2004). Reliability of the above-mentioned method was further verified through participation in the Third Interlaboratory Study on PFCs (April 2009), which was coordinated by the Institute of Environmental Studies (Amsterdam, Holland). Our laboratory reported satisfactory results for the water samples (z-scores \2). The analytical procedure used for this study was performed according to the ISO method entitled Determination of PFOA and PFOS Method for Unfiltered Samples Using Solid-Phase Extraction and Liquid Chromatography/Mass Spectrometry (published in 2009) with slight modifications. Thus, we deemed that the results of this study are accurate and precise. Results and Discussion The results were not compared site by site given the broad geographic scale of the sampling design (nationwide coverage) and due to limitations inherent to the sampling procedure (i.e., absence of systematic analyses on all of the raw-water sources supplying the same drinking-water treatment plant; only two samples taken at a 1-year interval during the same season; and lack of information on the treatments used at each drinking-water treatment plant). The results were therefore interpreted on a nationwide scale, and analyses are thus based on a large and robust data set. This approach made it possible to observe trends, some of which lend support to previous reports and others that require further investigation to be confirmed. PFCs in Raw Water (First Sampling Campaign) The study involved drinking-water facilities supplied by groundwater and surface water. Due to the sampling strategy, groundwater samples were predominant, accounting for 62% of the 262 collected samples. In 132 samples (50%), no PFCs were observed above the method s LOD. In 64 samples (24%), at least 1 PFC was detected at trace levels ranging from the LOD (1.3 ng/l) to the LOQ (4 ng/l). In 66 samples (25%), at least 1 PFC was detected at a concentration greater than the LOQ. The majority of these 66 samples (61 [92%]) contained at least 1 other PFC at trace levels. Information on the analytical results for each PFC according to the water source is listed in Table 1. Concentration ranges of the most frequently detected PFCs were\4 to 62 ng/l (PFOS),\4 to 32 ng/l (PFHxS), \4 to 28 ng/l (PFHxA), and\4 to 12 ng/l (PFOA). At all sampling sites, PFNA, PFBS, and PFBA were detected only rarely and at low concentrations. These concentrations ranged from \4 to 14 ng/l (PFNA), \4 to 6 ng/l (PFBS), and \4 to 8 ng/l (PFBA). PFPeA and PFHpA were infrequently detected but sometimes at high concentrations (40 ng/l). PFDA was only detected in 1 sample at a trace level. Our results are within the range of previously reported values for sites contaminated by diffuse pollution. Our investigations did not show any heavily contaminated sites. We compared our data with those of two earlier studies (Loos et al. 2009, 2010). These two studies were selected for comparison with our results for four reasons. First, a large number of samples ([100) were monitored on the same continent (Europe). Second, the analyzed PFCs are almost the same as those included in the present study. Third, the studies aimed to monitor groundwater and surface-water contamination separately. Finally, the examination of water known to be heavily polluted was not the objective of the studies. The comparison data are listed in Supplemental Tables A5 and A6. Regarding average and median PFC concentrations, the data comparison did not show any significant differences, especially in groundwater. Regarding the percentage of samples greater than the LOD and the range of PFC levels, the earlier studies (Loos et al. 2009, 2010) exhibited higher values, particularly for long-chain PFCs (C C8) in surface water. The different sampling strategies employed may explain the discrepancy in the results. Unlike the two other studies, our sites were representative of the quality of drinking-water sources and not of the overall contamination of the rivers.

5 Arch Environ Contam Toxicol (2012) 63: Table 1 Summary of analytical results of perfluorinated compounds in raw- and treated-water samples (first sampling campaign) PFBS PFHxS PFOS PFBA PFPeA PFHxA PFHpA PFOA PFNA PFDA SW a GW b SW GW SW GW SW GW SW GW SW GW SW GW SW GW SW GW SW GW Raw water n % [LOD c % [LOQ d Maximum \1 1 (ng/l) Average (ng/ \1 \ \1 \1 \1 1 \1 1 \ \1 \1 \1 \1 L) Median (ng/ \1 \1 \1 \1 1 \1 \1 \1 \1 \1 \1 \1 \1 \1 1 \1 \1 \1 \1 \1 L) Treated water n % [LOD c % [LOQ d Maximum \1 \1 (ng/l) Average (ng/ \ \ \ \1 1 \1 \1 L) Median (ng/ L) \1 \ \1 \ \ \1 \1 \1 \1 a Surface water b Groundwater c Frequency of detection d Frequency of quantification The spatial distribution of the water sources where the presence of PFCs was observed is presented in Fig. 1. The 66 contaminated samples came from 46 departments. Mountainous regions or those with small urban centers were less affected by PFC contamination than industrial regions crossed by major rivers. The departments around Paris and those crossed by the Loire, Rhône, or Moselle rivers accounted for 26 of the 46 departments that showed contamination. The anthropogenic origin of these compounds is clearly demonstrated by the spatial distribution of the contaminated sites. Moreover, 38% of the 66 additional samples potentially affected by releases from industrial or commercial activities contained PFCs at quantifiable levels. A lower percentage (21%) of quantifiable PFC levels was observed for the 196 other samples with the most significant flow in the department or randomly selected in the department. However, no significant relationship was found between the department s population density and the presence or the levels of PFCs in the water source. This absence of correlation may be due to the long-range transport of PFCs from industrial sites. A water source located in a department with low population density may be contaminated by industrial production or widespread commercial use located in an upstream department. Population density is therefore not always a good indicator in the case of diffuse PFC contamination, particularly when the sampling density (number of sites per km 2 ) is low, as in the present study (average of 0.4 sites/ 1000 km 2 ). Many cases of PFC presence have been reported in areas of low population density, such as the Arctic, due to atmospheric transport of volatile precursor substances (Ellis et al. 2004) or agricultural areas due to polluted sludge applied to fields (Skutlarek et al. 2006). PFCs in Raw Water (Data Compiled From Two Sampling Campaigns) As previously observed (Quiñones and Snyder 2009), PFOS, PFHxS, PFOA, and PFHxA were the most frequently detected PFCs in this study. The occurrence frequencies of each PFC are listed in Table 2. These data are also represented graphically (Supplemental Fig. A7). PFOS was more frequent in surface-water samples, whereas short-chain PFCs (PFHpA, PFHxA, PFHxS, PFPeA, PFBA, and PFBS) were more frequent in groundwater samples. The occurrences of PFOA and PFNA were evenly

6 6 Arch Environ Contam Toxicol (2012) 63:1 12 Fig. 1 Map of major French rivers and cities. The black triangles represent all sampling locations where at least one PFC was quantified. Island territories (Corsica, Guadeloupe, Réunion, and Martinique) and French Guyana are not shown, but no PFCs were found that were greater than the limit of quantification (4 ng/l) at these sampling sites. Supplementary data associated with this figure (concentrations at each sample site and zooms of areas surrounded by grey circles) are listed in Supplemental Table A3 and Figs. A3-1, A3-2 distributed between the two types of water source. Only three carboxylates (PFOA, PFNA, and PFHxA) were detected in surface water, whereas six (PFOA, PFHxA, PFHpA, PFNA, PFBA, and PFPeA) were detected in groundwater. It has been noted that PFCs with short perfluorocarbon chain lengths and a carboxylate head group have decreased sorption potential (Higgins and Luthy 2006). Moreover, it has been recently observed that contrasts in perfluoroalkylate concentrations between surface and deeper-soil samples tended to be more pronounced in long-chain than in shorter-chain cogeners (Washington et al. 2010). These data and our results support the suggestion that the environmental mobility of PFCA and PFAS increase with decreasing chain length. In addition to this behavior, another possible phenomenon may explain the high presence of short-chain congeners in groundwater: precursor degradation during soil infiltration (Liu et al. 2007). The resulting metabolites may more easily reach the groundwater aquifer than PFASs or PFCAs with long perfluorocarbon chain lengths. As listed in Table 2, the highest concentrations for PFOS (62 ng/l), PFHxA (139 ng/l), and PFNA (52 ng/l) were observed in surface-water samples. This observation may be the result of the presence of high industrial discharges of PFOS, PFHxA, and PFNA into rivers. The other PFCs (PFBS, PFHxS, PFHpA, PFOA, PFBA, and PFPeA) were detected at their highest concentrations in groundwater samples. It is conceivable that these PFCs are mainly breakdown products of PFC precursors. Biodegradation pathways of a fluorotelomer alcohol (8:2 FTOH) has been proposed (Wang et al. 2009). This compound was rapidly converted to fluorotelomer acids, which were subsequently converted to PFCAs, such as PFOA and PFHxA. The degradation of fluorotelomer compounds generates chemicals with greater environmental mobilities. The limited removal of short-chain PFCAs by soils (Murakami et al. 2009; Washington et al. 2010) is consistent with our observation that these chemicals are present in groundwater at high concentrations. Surprisingly, for PFASs and PFCAs, high concentrations did not always mean high frequencies of detection. In surface-water samples, the highest concentrations of PFNA and PFHxA were 52 and 139 ng/l, respectively, whereas their frequencies of detection were only 2% and 4%, respectively. In comparison, the highest concentration of PFOS, which was the most frequently quantified compound in surface-water samples (36%), was 62 ng/l. These results suggest that some river waters are greatly affected by upstream industrial sources, from which specific PFCAs (PFNA or PFHxA) are used and discharged into the aquatic environment. We recently localized a polyvinylidene fluoride (PVDF) production facility upstream of the sites where PFNA was detected. This PFCA is mainly Table 2 Frequency and maximum concentration of each PFC in raw water PFBS PFHxS PFOS PFBA PFPeA PFHxA PFHpA PFOA PFNA PFDA SW GW SW GW SW GW SW GW SW GW SW GW SW GW SW GW SW GW SW GW % [LOQ b Maximum concentration (ng/l) \4 12 \ \ \4 \4 SW surface water, GW groundwater a Data compiled from both sampling campaigns, i.e., 135 surface-water samples and 196 groundwater samples b Frequency of quantification

7 Arch Environ Contam Toxicol (2012) 63: used to facilitate the aqueous polymerization of PVDF (Prevedouros et al. 2006). A facility using high quantities of PFHxA is suspected of being the input source of this PFCA. For sampling sites that were sampled during both sampling campaigns, we examined the difference in total PFC concentration. To account for analytical uncertainty and to avoid giving too much weight to weak variation of low concentrations, our results are expressed in ng/l and not in percentages (e.g., an increase of 2 ng/l for a total PFC concentration of 4 ng/l has little analytical significance, although it would result in a relative increase of 50%). Therefore, 65 raw-water samples were compared (31 groundwater and 34 surface-water samples), and the results are plotted in Fig. 2. The total PFC concentrations were generally identical between the two sampling campaigns. In 21 groundwater (67%) and 27 surface-water samples (79%), the observed difference ranged from 0 to 10 ng/l (absolute value). This pattern suggests that PFC contamination remains present and stable after an interval of 1 year between two sample collections. However, 6 raw-water sites exhibited a difference of[30 ng/l. Among these rawwater samples, there were 3 surface-water and three groundwater samples, 2 of which were wells supplied by alluvial aquifers. Based on these data, high variation in concentrations may be observed in surface-water samples or in wells supplied by alluvial aquifers with short residence times compared with more confined groundwater. No clear concentration increase or decrease was found between the two sampling campaigns, but the interval of just 1 year is probably too short for showing any temporal trends in PFC contamination. The number of quantified PFCs per sample is plotted in Fig. 3. On the basis of the total number of contaminated samples from each sampling campaign, 59% of the first campaign samples and 44% of the second campaign Number of sampling points Groundwater Surface water [0-10] [10-20] [20-30] [30-50] [50-60] [60-80] [80-200] Intervals of concentration differences (ng/l) Fig. 2 Differences in total perfluoroalkyl concentration between rawwater samples collected during the two campaigns (intervals in ng/l) % samples on the base of contaminated samples samples contained only one PFC at a quantifiable level. Eight PFCs were simultaneously quantified in a sample of the second campaign. However, in most cases, fewer than three PFCs per sample were quantified. No significant relationship between quantified PFCs was observed in the present study, except for samples collected from the same river. The profile pattern PFHxA [ PFNA [ PFOA was observed at six sampling points in this river covering 200 km. None of the other samples collected in France exhibited this profile pattern. This result indicates that this river is polluted by these three PFCAs, perhaps from contamination related to their heavy use by industries located in the upper river basin (especially a PVDF production facility and an industrial facility using high quantities of PFHxA recently located upstream of these six sampling points). This suggests that identification of pointsource inputs may require intensive sampling to identify the facilities that are accountable for PFC contamination. We investigated the extent of the occurrence of PFCs in groundwater, comparing the results with observations from surface-water samples (Supplemental Table A8). These results indicate that the frequency of contaminated samples in groundwater and surface waters during the first sampling campaign was greater for surface waters (35% vs. 19%), but we did not identify the same compounds in both water sources, as described previously. In the second sampling campaign, the opposite pattern was observed, with surface waters being less frequently contaminated than groundwater (53% vs. 78%), although this may be due to the sampling strategy (i.e., confirmation of PFC presence). No relationship was found between geological data (e.g., depth of intake, confined or unconfined wells) and the occurrence of PFCs in groundwater aquifers. Many PFCs are excellent surfactants, which suggest that these chemicals are highly enriched in the surface film. It 9 1st campaign 2nd campaign Number of quantified PFC per sample Fig. 3 Distribution of the percentage of contaminated samples according to the number of PFCs quantified per sample

8 8 Arch Environ Contam Toxicol (2012) 63:1 12 has been shown that the enrichment factors for PFOS (concentration in the 50-lm surface microlayer/concentration in subsurface water [[30 cm depth]) are as high as 24 to 109 in coastal waters (Ju et al. 2008), where surface microlayer samples were collected using glass-plate dipping method. In the present study, 32 raw-water samples were collected using two procedures. Surface-water samples were collected from the surface layer to include the air water interface. Water samples were collected 30 cm below the surface with a submerged bottle. No statistical difference in PFC concentrations between surface-water and water samples was observed. This may indicate that our sampling methodology was not sufficiently precise to detect surface film enrichment. In the scientific literature, PFOA and PFOS are the two most commonly investigated PFCs. In effect, the ISO method is only applicable to the determination of these two compounds. We examined whether these two substances could be representative of PFC contamination and used as indicative warning alerts for characterizing pollution by PFCs. Based on the sum of PFOA and PFOS alone, overall PFC contamination was underestimated by [50% in 9 samples and 11 samples for the first and the second campaigns, respectively. According to the sum of PFOA and PFOS alone, we would have also concluded the absence of PFC contamination in 9 samples for the first and 9 samples for the second campaign, whereas other PFCs were present at a quantifiable level. In the majority of cases, the total perfluoroalkyl concentration was\25 ng/l. However, in 1 sample, a total perfluoroalkyl concentration of 94 ng/l was determined. PFPeA (40 ng/l), PFHpA (23 ng/l), PFHxA (23 ng/l), and PFBA (8 ng/l) were the four compounds detected in this water sample. In summary, these results show that the PFC contamination would have been underestimated if only PFOA and PFOS had been taken into account. To address this issue, it is therefore necessary to identify other PFCs, such as PFHxS and PFHxA, that are likely to be found in water. Based on the sum of PFHxA, PFHxS, PFOA, and PFOS, the number of samples for which the concentration would have been underestimated decreases to two samples for the first campaign and two samples for the second campaign. Similarly, according to the sum of these four compounds, we would have also conluded the absence of PFC contamination in one sample and two samples for the first and the second campaign, respectively. These results show the usefulness of analyzing PFCs, other than PFOA and PFOS, to avoid overlooking contamination by a PFC. PFCs in Treated Water (First Sampling Campaign) The samples represented the quality of water leaving the treatment plant and entering the distribution system. In this campaign, 41 treated water samples were analyzed because PFCs had been quantified in their raw water. The results are listed in Table 1. In two samples (5%), no PFCs were observed that were greater than the method s LOD. For 16 samples, at least 1 PFC was detected at trace levels ranging from the LOD (1.3 ng/l) to the LOQ (4 ng/l). For 23 samples, at least 1 PFC was detected at a concentration greater than the LOQ. All 23 samples contained at least 1 other PFC at trace levels. Concentration ranges of the most frequently detected PFCs were\4 to 21 ng/l (PFHxA),\4 to 16 ng/l (PFOS), \4 to 13 ng/l (PFHxS) and \4 to 9 ng/l (PFOA). At all sampling sites, PFBA, PFHpA, and PFNA were detected only rarely and at low concentrations. These concentrations ranged from \4 to 8 ng/l (PFBA) \4 to 11 ng/l (PFHpA and PFNA). PFPeA was also infrequently detected but sometimes at high concentrations (31 ng/l). PFBS was only detected at trace levels. PFDA was not detected in any sample. The sum of all of the determined components was never [100 ng/l (maximum value 76 ng/l). The results were compared for the 41 paired samples of raw water and treated water. The distribution (number of samples) between raw and treated water is plotted in Fig. 4 for each PFC when its concentration was greater than the LOQ. As shown in Fig. 4, the occurrence of perfluoroalkyl sulfonates (PFOS, PFHxS, and PFBS) was lower in treated water compared with raw water. This difference in abundance suggests that water treatments are relative effective in removing this group of perfluorinated substances. Nevertheless, further study is needed to confirm this hypothesis. Regarding perfluoroalkyl carboxylates, the trend is not as clear. PFOA was more frequently quantified in raw water as were perfluoroalkyl sulfonates. PFBA and PFPeA were detected at the same frequency, whereas PFHxA and PFHpA were more frequent in treated-water samples. Number of samples Raw water Treated water Fig. 4 Comparison of 41 paired samples of raw and treated water (first sampling campaign). Number of samples where the PFC level is greater then the limit of quantification (4 ng/l for each compound)

9 Arch Environ Contam Toxicol (2012) 63: To account for analytical uncertainty, the effectiveness of drinking water treatment plants was studied when the total PFC concentration of raw water was [10 times the LOQ (i.e., 40 ng/l). Thus, only four treatment plants were studied for treatment effectiveness. At three treatment plants, a significant decrease in PFC concentration was observed in treated water and in one plant (using ultraviolet treatment), the quality of treated water was equivalent to that of raw water. When a decrease of PFC concentration was observed in a treatment plant between the raw and the treated water, it was often due to dilution, because some water-treatment plants are supplied by many wells, which are not always all polluted by PFCs. Moreover, we observed greater PFCA concentrations in treated water compared with raw water at a drinking-water utility (Table 3) using biological treatment (coagulation, sedimentation, sand filtration, ozonation, activated carbon filtration, and chlorination). Some investigators (Takagi et al. 2008, 2011) have also observed negative removal ratios. They argue that PFCs begin to be desorbed from activated carbon after the carbon is saturated and are less retained at low water temperatures. However, this behavior has only been described for PFOA and PFOS (Takagi et al. 2011), which are known to have greater sorption capacity than their analogs of shorter chain length (Higgins and Luthy 2006). Table 3 shows that there was no significant desorption of PFOA and PFOS, whereas the concentrations of PFHxA, PFHpA, and PFPeA greatly increased in the treated water. Because short-chained PFCs have a well-established tendency to be less sorptive than PFOA and PFOS and are considered to be difficult to remove from drinking water by common treatment techniques, including filtration over activated carbon (Wilhelm et al. 2010), their negative removal ratio can be explained by a degradation of fluorotelomer compounds during water treatment. Moreover, a fluorotelomer manufacturing plant was recently localized 25 km upstream from this drinkingwater treatment plant, which is directly supplied by river water. In this study and others, the gap in our knowledge of the concentrations of PFC precursors in the influent water hinders any estimation of removal efficiency of the drinking water treatment processes. Further investigation is needed to confirm the hypothesis of biological and/or chemical degradation of precursors during water treatment. PFCs in Treated Water (Second Sampling Campaign) During this sampling campaign, 69 treated water samples were analyzed. The results are listed in Supplemental Table A9 and Fig. A10 and confirmed those of the first campaign. In 7 samples (10%), no PFCs were observed that were greater than the method s LOD. For 27 samples, at least 1 PFC was detected at a trace level ranging from the LOD (1.3 ng/l) to the LOQ (4 ng/l). For 35 samples, at least 1 PFC was detected at a concentration greater than the LOQ. The majority (94%) of these 35 samples contained at least 1 other PFC at trace levels. Of the PFCs measured, PFHxA, PFOS, and PFHxS were the most frequently quantified. They were found to be greater than the LOQ (4 ng/l for all compounds) in 28%, 28%, and 20% of the samples, respectively. The concentrations ranges were \4 to 125 ng/l (PFHxA), \4 to 22 ng/l (PFOS), and \4 to 18 ng/l (PFHxS). The high concentration of PFHxA (125 ng/l) suggests that there are possible point sources from industries in the immediate vicinity of the drinking water treatment plant. At all sampling sites, PFBS and PFNA were detected only rarely and at low concentrations. These concentrations ranged from \4 to 13 ng/l (PFBS) and \4 to 23 ng/l (PFNA). The quantification frequencies for PFPeA, PFHpA, PFBA, and PFOA were similar (10% to 14% of samples). Their respective highest concentrations were 27, 19, 14, and 12 ng/l. PFDA was not detected in any sample. The sum of all of the determined components was[100 ng/l at one sampling point (156 ng/l). Only four drinking water treatment plants with a total PFC concentration[40 ng/l could be studied for treatment effectiveness (Supplemental Table A11). In all four cases, PFC concentration decreased by 21% to 96%, but these decreases could all be attributed to dilution with non PFCcontaminated water sources. In eight drinking water treatment plants (Supplemental Table A12), PFC concentrations were greater in treated water than in raw water. Most plants (seven of the eight) used activated carbon to treat raw water. In these eight plants, the PFOA and PFOS concentrations in raw and treated waters did not change, reflecting the ineffectiveness of treatment on these compounds. Certain PFCs (PFBA, PFBeA, PFHxA, and PFHpA) were only quantified in treated waters, suggesting Table 3 Concentrations (ng/l) of screened PFCs in water samples collected at a drinking-water utility PFBS PFHxS PFOS PFBA PFPeA PFHxA PFHpA PFOA PFNA PFDA Total PFCs Raw water \4 Traces a Traces \4 Traces Traces \4 Traces \4 \4 \4 Treated water \4 Traces Traces \4 \4 76 a Concentration between the LOD and the LOQ (4 ng/l)

10 10 Arch Environ Contam Toxicol (2012) 63:1 12 two explanations for ineffective PFC removal: Either (1) these PFCs are released by saturated activated carbon or (2) they result from the degradation of precursors during the treatment process (e.g., biological decomposition in the activated carbon; preliminary chemical decomposition during ozonation). PFOS leaching from activated carbon (Takagi et al. 2011) was clearly demonstrated in only one treatment plant. Further investigation is needed to confirm the presence of fluorotelomer compounds in raw water and to understand the fate of PFCA precursors during water treatment. Membrane filtration was always found to be an effective treatment technique for removing the screened PFCs. Implications for Human Exposure Our investigations did not show any heavily contaminated sites, as have been reported in Germany (Skutlarek et al. 2006) and the United States (Anderson-Mahoney et al. 2008; Emmett et al. 2006; MDH 2009a). With only three compounds (PFHxS? PFBS? PFOS), PFAS represents 53% of the total PFC concentration measured in raw-water samples. This observation confirms that environmental contamination is still considerable, despite the progressive phasing-out of the commercial production of PFAS-based compounds by major manufacturers. In treatedwater samples, the PFAS contribution decreases to 37% of the total PFC concentration, confirming the relative effectiveness of the water treatment. At the same time and as previously described, the presence of short-chain PFCAs increased in treated water, perhaps reflecting a degradation of PFCA precursors during treatment. Most studies have focused on PFOS precursors, and only a few studies have investigated the degradation of PFC precursors into PFCA. Determination of these compounds represents an interesting avenue for future research, especially in treated water. Although shorter-chained PFCAs are considered to be less harmful than PFCs with long perfluorocarbon chain lengths and sulfonate head groups, they may be representative of raw-water pollution by PFCA precursors and thereby be used as indicative warning alerts. Furthermore, mixtures of shortchain fluorochemical molecules are being introduced as substitutes for PFOS and PFOA because chain length has a large impact on bioaccumulation and toxicity (Renner 2006). These new compounds are presented as environmentally friendly alternatives, but they are difficult to remove from drinking water by common treatment techniques and are thought to become the main emerging contributors to total PFC levels in drinking water in the future (Wilhelm et al. 2010). Due to their estimated half-life (Washington et al. 2009), PFC precursors may constitute an important source of shorter-chained PFCs in the environment for the coming decades. Currently there are no existing national regulations regarding PFCs in drinking water, although a few agencies have issued guidelines on recommended maximum allowable levels. It is also important to note that the currently available guidelines do not consider the many recent human and animal studies published after the guidelines had been drawn up. Several of these studies show effects at lower levels than the studies that were available when the guidelines were developed. The Minnesota Department of Health has issued a chronic noncancer health risk limit of 300 ng/l in drinking water for PFOA or PFOS (MDH 2009b, 2009c). The Drinking Water Commission of the German Ministry of Health has deduced a strictly healthbased guidance value for safe lifelong exposure for all population groups of 300 ng/l for combined PFOA and PFOS concentrations in drinking water (Trinkwasserkommission 2006). A health-based drinking water concentration protective for lifetime exposure of 40 ng PFOA/L has been developed through a risk-assessment approach by the New Jersey Department of Environmental Protection (Post et al. 2009). The United States Environmental Protection Agency (USEPA) has developed provisional health advisory short-term values for PFOS and PFOA of 200 and 400 ng/l, respectively (USEPA 2009). In the field of water policy, the European Community considers PFOS a potential priority hazardous substance (2008/105/EC 2008). Here, we assessed the concentrations of PFOA and PFOS found in treated-water samples in light of the abovelisted tentative guidelines. In the present study, the highest concentrations of PFOS and PFOA were 22 and 12 ng/l, respectively. These values are well below the guidelines proposed in the United States and Germany. Increases in short-chain PFCA occurrence and levels in treated water were reported in the present study. In the future, further research should be directed toward the study of the PFC toxicity of compounds other than PFOA and PFOS (Bjork and Wallace 2009). Risk assessments should also be developed to interpret environmental exposures to mixtures of PFCs, such as those detected in drinking water in this study. The data published in this study suggest that some drinking water treatment steps might convert PFC precursors to PFCA. Some of these likely PFC precursors (fluorotelomer acids) are supposed to be more toxic than PFCAs (Phillips et al. 2007). Further investigation is needed to confirm that in certain cases drinking-water treatment might decrease relative toxicity for the water consumer. Acknowledgments This study was supported by the French Ministry of Health. We thank the departmental and regional Ministry of Health personnel for their invaluable contributions to this work in collecting water samples as well as their helpful comments and continued support. We also thank John Washington (USEPA, Athens,

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