Environ. Sci. Technol. 2010, 44, 4083–4088
Temporal Trends of Perfluorinated Surfactants in Swedish Peregrine Falcon Eggs (Falco peregrinus), 1974-2007 ¨ M , * ,† KATRIN E. HOLMSTRO ANNA-KARIN JOHANSSON,† ANDERS BIGNERT,‡ PETER LINDBERG,§ AND URS BERGER† Department of Applied Environmental Science (ITM), Stockholm University, SE-10691 Stockholm, Sweden; Department of Contaminant Research, Swedish Museum of Natural History, SE-10405 Stockholm, Sweden; Department of Zoology, University of Gothenburg, SE-40530 Gothenburg, Sweden
Received January 11, 2010. Revised manuscript received April 10, 2010. Accepted April 13, 2010.
Perfluorinated alkyl substances (PFAS) are today known to be globally distributed environmental contaminants. In the present study, concentrations of PFAS were analyzed in Swedish peregrine falcon eggs (Falco peregrinus), collected between 1974and2007.Analytesincludedinthestudywereperfluorinated carboxylates (PFCAs; carbon chain lengths C6-C15), perfluorinated sulfonates (PFSAs; C4, C6, C8, and C10), and perfluorooctane sulfonamide (PFOSA). The predominant PFAS was perfluorooctane sulfonate, PFOS (83 ng/g wet weight (w wt) mean concentration in samples from 2006), followed by perfluorotridecanoate, PFTriA (7.2 ng/g w wt) and perfluoroundecanoate, PFUnA (4.2 ng/g w wt). PFCA concentrations increased exponentially over the studied time. In contrast, concentrations of PFOS and perfluorohexane sulfonate (PFHxS) increased initially but leveled off after the mid 1980s. This is different from previously observed temporal trends in marine organisms. The present study is the first to establish temporal trends for PFAS in terrestrial biota. The results indicate potential differences between marine and terrestrial biota regarding sources of PFAS exposure and response to emission changes. The toxicological implications of PFAS exposure for the falcons are not known, but according to recent findings impaired hatching success and sublethal toxicological effects from PFOS exposure in the Swedish peregrine falcon cannot be ruled out.
Introduction Perfluorinated alkyl substances (PFAS) are a group of environmental pollutants brought to scientific attention during the past decade. PFAS consist of a completely fluorinated carbon backbone of 4-15 carbon atoms in length, linked to different functional groups, such as, for example, a sulfonic or carboxylic acid group. PFAS and their precursors are used in a wide variety of industrial and consumer * Corresponding author phone: tel: +46 8 508 28885; e-mail:
[email protected]. † Stockholm University. ‡ Swedish Museum of Natural History. § University of Gothenburg. 10.1021/es100028f
2010 American Chemical Society
Published on Web 05/06/2010
applications such as fire fighting foams, surface treatments, and as insecticides (1). Perfluorooctane sulfonate (PFOS) is the predominant PFAS in the biotic environment, but a range of other PFAS of different chain lengths and functional groups are also present (2). Due to concerns regarding toxicity and persistence, PFOS was included in the Stockholm convention on persistent organic pollutants in 2009. The peregrine falcon (Falco peregrinus) is a migratory raptor found in a variety of terrestrial habitats in the Northern Hemisphere. In the mid 1970s the species was critically endangered due to high concentrations of pollutants affecting the eggshell thickness and reproduction (3, 4). After the ban of several pesticides, polychlorinated biphenyls, and mercury in many European countries in the late 1970s, peregrine falcon populations have recovered. In the 1970s less than 20 pairs were left in Sweden, whereas the current population size is estimated to more than 200 pairs, partly also as a result of a successful captive breeding and reintroduction program (5). The peregrine falcon is a valuable species in the Swedish fauna, and large efforts have been made to help the population to recover. It is thus important to monitor this species for emerging pollutants and possible new threats. PFAS are known to be globally distributed environmental contaminants (2). High concentrations have been reported in several bird species (6, 7), including the Swedish environment (8), but contamination levels of perfluorinated compounds have not yet been described in peregrine falcons. The aim of this study was to determine concentrations and temporal trends of PFAS in peregrine falcon eggs. For substances like PFAS (including precursors) where both water and air borne transport is of potential importance differences in exposure between terrestrial and marine species could be expected. The peregrine falcon should, as a terrestrial species, be exposed to predominantly airborne pollution. Marine birds on the other hand are exposed to both airborne and waterborne pollution integrated in their prey. Little information is available on PFAS concentrations in terrestrial species, in particular for the longer chain perfluorinated carboxylates. Several studies have shown increasing trends of PFAS in bird eggs (8, 9) and other marine biota during the past decades (10, 11). The present study is the first to describe temporal trends for perfluorinated surfactants in a terrestrial species.
Materials and Methods Sampling and Study Design. Peregrine falcon eggs from a population breeding in the southwest of Sweden (see Supporting Information (SI) Figure S1) were collected between 1974 and 2007 within the Swedish Society for Nature Conservation monitoring program with permission from the Swedish Environmental Protection Agency. All eggs included in the present study were unfertilized or addled eggs and were stored at -20 °C until analysis. Due to the low breeding success of the peregrine falcons only few eggs were available from the first 20 years of the studied time period, and no eggs were available between 1987 and 1991. Therefore all eggs up to 1999 were analyzed individually. From the year 2000 and onward more eggs were available and pooled samples were analyzed. Each pool contained aliquots from five to eight individual eggs. To get a measure of the within year variation during later years, 10 eggs from 2006 were analyzed individually (see also SI Table S1). The same set of samples has also been characterized for brominated flame retardants (unpublished data) (12). Extraction and Clean-Up. Sample extraction was based on the method described by Verreault et al. (9). In short, 0.2-0.3 g of homogenized egg was transferred to a polyproVOL. 44, NO. 11, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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pylene (PP) centrifuge tube, and spiked with the mass-labeled PFAS as internal standards (see SI Table S2 for a full description of the internal standards). Extraction was performed with 2 × 5 mL acetonitrile in an ultrasonic bath. The combined extracts were concentrated to 1 mL under a gentle stream of nitrogen and subjected to dispersive clean up on graphitized carbon (Supelclean ENVICarb 120/400, Supelco, Sigma-Aldrich, Stockholm, Sweden) and acetic acid in a centrifuge tube. A volume of 0.5 mL of the clear extract was transferred to an autoinjector vial and 0.5 mL of aqueous ammonium acetate (4 mM) was added. Finally, 50 µL of the volumetric standards 3,5-bis(trifluoromethyl)phenyl acetic acid and perfluoro-3,7-dimethyl-octanoic acid in methanol was added (see also SI Table S2). Instrumental Analysis. Aliquots of the final extracts were injected automatically onto two separate systems. This was done to achieve the lowest possible detection limit for each individual analyte. Perfluorinated carboxylates (PFCAs) with chain lengths C6-C14 in the peregrine falcon eggs were analyzed on a high performance liquid chromatography system (HPLC; Alliance 2695, Waters, Milford, MA) coupled to a tandem mass spectrometer (MS-MS; Quattro II, Micromass, Altrincham, UK). Compound separation was achieved on an Ace 3 C18 column (150 × 2.1 mm, 3 µm particles, Advanced Chromatography Technologies, Aberdeen, Scotland) with a binary gradient of buffered (2 mM ammonium acetate) methanol and Milli-Q water (from a water purification unit, Millipore AB, Solna, Sweden). LC and MS instrumental parameters are described elsewhere (13). Quantification was performed in selected reaction monitoring chromatograms using the internal standard method. 13C2-PFHxA, 13C4-PFOA, 13C5-PFNA, 13C2-PFDA, 13 C2-PFUnA,13C2-PFDoA were employed as internal standards for the different PFCAs (see SI Table S2 for the monitored ion transitions, and further information on internal standards). Only linear isomers were included in the quantification. Perfluorinated sulfonates (PFSAs), PFOSA, and PFPeA were analyzed on a HPLC system (Acquity Ultra Performance LC, Waters, Milford, MA) coupled to high resolution mass spectrometry (HRMS, Q-ToF Premier, Micromass, Manchester, UK) operated at a resolution of 10 000 (fwhm). Compound separation was achieved on the same Ace 3 C18 column as described above. Quantification was performed in extracted high resolution mass chromatograms (see SI Table S2 for ions monitored) using the internal standard method. 13 C4-PFOS was employed as internal standard for PFSAs and PFOSA, and 13C2-PFDoA for PFPeA. Due to the lack of an analytical reference standard for PFPeA, this analyte was quantified using the response factor of PFTeA. Only linear isomers were included in the quantification. Quality Assurance. Solvent injections were done regularly to monitor the instrumental background. The injections did not reveal instrumental background of the target analytes in the HPLC-MS-MS system. However, injections revealed a background of C6-C14 PFCAs in the HPLC-HRMS system. These analytes were therefore analyzed on the HPLC-MSMS system. A laboratory blank sample (empty centrifuge tube spiked with internal standards) was extracted along with every batch of egg samples. Traces of PFHxA, PFHpA, PFOA, and PFOSA were occasionally found in the blanks, resulting in an elevated method detection limit (MDL) for these analytes. No traces were found of any of the other analytes in the blanks. MDLs for the compounds were defined at a signal-to-noise ratio of three, or three times the signal (if present) in the laboratory blank experiments. A list of compound specific MDLs is given in SI Table S3. Recovery rates for the internal standards spiked to peregrine falcon eggs are given in SI Table S4. 4084
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Subsamples of a larger control sample of fish muscle homogenate from an interlab comparison study (ILC) (14) were repeatedly extracted and analyzed during the study (n ) 4). The results deviated from the ILC median results by 12-28% for the different analytes. A full description of the results from the control samples is given in SI Table S5. Statistics. To test for significant changes in the individual PFAS concentrations over time, a log-linear regression analysis was performed. A linear trend on a log scale was fitted to the geometric mean values. Also, the nonparametric Mann-Kendall trend test was carried out to check for the possibility that false trends were detected, caused by high leverage by one or a few extreme points in the beginning or end of the time series (15). To test for nonlinear trend components, a 7-point running mean smoother was applied. Analysis of variance (ANOVA) was used to test whether the smoother explained significantly more of the variation in concentration over time than the regression line (16, 17). The latest eight years of the studied time (2000-2007) were additionally selected and the regression analysis described above was repeated. Principal component analysis (PCA) was performed on the proportions of single PFCA concentrations to the sum of PFCAs to study the change in homologue pattern over time. The percentage of each individual PFCA relative to the sum of PFCAs was calculated and log-transformed prior to PCA analysis. Before the PCA-scores were plotted they were centered and scaled to 100%. The significant level was set to 5% (R ) 0.05). To check for significant changes in homologue pattern over time Hotelling’s T2-test was applied. To keep the desired Type I error rate of 0.05 the critical significance level was adjusted to 0.017 with the Bonferroni method.
Results and Discussion PFHxS, PFOS, and PFTriA were detected in the falcon egg samples from as early as 1974, the first year analyzed in this data set. Onward in time PFCAs of the chain lengths C9-C15 appeared, as well as PFDS. PFBS, PFHxA, PFHpA, and PFOA could not be detected above their respective MDLs (see SI Table S3) in any of the samples, whereas PFOSA was detected in only two samples (SI Table S2). PFAS concentrations in the eggs sampled in 2006 (n ) 10) are given in Table 1. Concentrations of PFSAs. The overall PFAS profile was dominated by PFOS, with a maximum concentration of 220 ng/g wet weight (w wt) in an individual sample from 2006. Compared to other birds monitored in the Nordic fauna the peregrine falcon had moderate concentrations of PFOS in the eggs. The mean PFOS concentration of 83 ng/g w wt in 2006 is comparable to mean concentrations in herring gull eggs from Northern Norway (40 ng/g w wt, sampled in 2003) (9) or in glaucous gull eggs from Svalbard (104 ng/g w wt, sampled in 2004) (6) but lower than mean PFOS concentrations in egg yolk from several Korean bird species (185-314 ng/g w wt, sampled in 2006) (7). It should be noted, however, that PFAS predominantly partition into the yolk of the egg and that yolk concentrations and whole egg concentrations cannot be directly compared. Five different populations of guillemots in the Nordic environment have been monitored for PFOS (18), with a mean egg concentration of 15 ng/g w wt in Iceland, while the mean concentration from a Baltic guillemot population was as high as 400 ng/g w wt (sampled 2002-2005). Few terrestrial birds have been surveyed, but a recent Belgian study on PFOS concentrations in a terrestrial carnivore, the Eurasian Sparrow hawk (Accipiter nisus), showed PFOS concentrations ranging between 47.6-775 ng/g w wt (liver) (19). However, these liver concentrations cannot directly be compared with concentrations in eggs due to possible differences in tissue distribution of PFAS in different bird species (20).
TABLE 1. Concentrations of PFAS in Peregrine Falcon Eggs (n = 10) Sampled in 2006a analyte arithmetic mean concentration (standard error) and range [ng/g w wt]
slope of temporal increase 1974-2007 (log-linear regression)
doubling time 1974-2007 [years]
PFNA
PFDA
PFUnA
PFDoA
PFTriA
PFTeA
PFPeA
PFHxS
PFOS
PFDS
1.6 (0.40)
3.1 (2.3)
4.2 (2.3)
3.2 (1.3)
7.3 (2.7)
2.7 (1.1)
0.57 (0.24) 0.80 (0.38) 83 (49)
0.66 (0.61)
0.97-2.3
1.0-9.6
2.0-9.7
1.3-5.6
4.0-14
1.5-4.9
0.24-1.1
0.52-1.9
40-220
0.31-2.3
9.1%
7.8%
11%
9.6%
12%
7.7%
8.0%b
6.4%
5.6%
10%
p < 0.001* p < 0.001* p < 0.001* p < 0.001* p < 0.001*
p < 0.001* p < 0.020* p < 0.001* p < 0.001* p < 0.001*
7.6
slope of temporal increase/decrease 2000-2007 2.9% (log-linear regression) NS
8.9
6.3
7.2
5.6
9.0
8.7b
11
12
7.0
2.8%
-1.4%
-4.5%
-9.4%
-7.2%
-10%
-9.9%
2.3%
-7.4%
NS
NS
NS
NS p < 0.090 p < 0.032* p < 0.048* NS
NS
NS
a
Slopes and doubling times for the temporal trends of PFAS in peregrine falcon eggs are also given for the time periods 1974-2007 and 2000-2007, along with the p-values for the regressions. PFHxA, PFHpA, PFOA, PFBS, and PFOSA were not detected in any sample from 2006 above their respective MDLs (see SI Table S3). NS, not significant. b Based on eggs sampled 1992-2007.
PFHxS and PFDS were also found in the peregrine falcon eggs, but at considerably lower concentrations, adding up to no more than about 1% of the PFOS concentrations (SI Table S1). This is similar to the relationships reported for PFSAs in other bird species (6, 9). PFOSA was detected in only two egg samples (from 1992 and 1999). Concentrations were low (0.1 and 0.2 ng/g w wt), which is in agreement with observations in other birds, and supports the suggestion that (predatory) birds have the ability to transform or eliminate PFOSA efficiently (20). Concentrations and Contaminant Profile of PFCAs. The PFCA contamination profile was dominated by PFTriA followed by PFUnA. This is in agreement with other bird eggs studied for PFCAs such as Baltic common guillemot (20), glaucous gull and herring gull (6, 9). However, PFUnA and PFTriA were less dominant in the peregrine falcon eggs than in the guillemot and glaucous gulls. These two homologues contributed about 73% of the total amount of PFCAs in the guillemot, and 78% in the glaucous gull (6, 20), whereas in the falcon the contribution was only 51%. This implies a difference in exposure or pharmacokinetics between these species. The PFCA homologue pattern for the peregrine falcon egg samples from 2006 is shown in Figure 1. High concentrations of PFCAs have been reported in bird egg yolks from Korea, with mean concentrations of up to 200 ng/g w wt for PFUnA in parrot bill (7), whereas PFCA levels reported in bird eggs from Norway (herring gull and glaucous gull (6, 9)) and China (heron and egret (21)) fall in the same range as for the peregrine falcon (see SI Table S1). Temporal Trends of PFSAs. The concentration of PFOS in the falcon eggs ranged from 7.3 ng/g w wt in 1974 to an average of 83 ng/g w wt in 2006, and showed a rapid increase during the first 10 years of the studied time (1974-1984). After 1984 the concentrations reached a more steady level, with the running mean ranging between 80-90 ng/g w wt thereafter (Figure 2). A recently published estimate of the global production volumes of perfluorooctane sulfonyl fluoride (POSF), the starting material for PFOS and its precursors, showed a linear increase in production volume between 1975 and 1989 before leveling off and remaining constant between 1990 and 2000 (22). This estimation fits quite well with the temporal trend in the falcon eggs in the present study. A reported rapid
FIGURE 1. PFCA homologue concentrations measured in peregrine falcon eggs (n ) 10) sampled in 2006. The straight horizontal line shows the median concentration and the circular symbol and number represent the arithmetic mean. The 25th and 75th percentiles define the boxes. The whiskers represent the 10th and 90th percentiles. The asterisks represent observations >1.5 times the interquartile range from the edge of the box. decline in PFOS concentrations in seals from the Canadian Arctic in recent years (11) was tentatively connected to the production phase out by the main manufacturer in the U.S. by 2002 (22). Such a decline could, however, not be visualized in the present data set (Figure 2 and Table 1). The phase out by the major producer was however not the end of PFOS production, but production went on in several smaller facilities in Europe and was taken up in other countries, for example, in China (1). In the production estimate it was assumed that PFOS production before 1970 was minimal (22). Still, the egg sample from 1974 in this data set already contained a measurable concentration of PFOS. A comparison of the current PFOS time trend with a similar trend investigated in Swedish guillemot eggs from 1968-2007 gives a divergent picture (8, 23). Whereas PFOS concentrations in the falcon eggs level off around 1985, PFOS in the guillemot eggs has shown an increase from 1968 up until recent years where concentrations possibly seem to be leveling off (8, 23). It is likely that the difference in temporal VOL. 44, NO. 11, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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FIGURE 2. Temporal trends of PFSAs of chain lengths C6, C8, and C10 in Swedish peregrine falcon eggs collected between 1974 and 2007. Concentrations are given in ng/g w wt and error bars represent 95% confidence intervals of the geometric mean. Log-linear regression (dashed line, 1974-2007), and a seven-point running mean smoother (line) are shown. trends can be attributed to the different routes of exposure (terrestrial vs marine) for the two species. PFOS has a low KOC (3-3.5 (24)) and is subsequently not retained in soil (25) but would be washed out by rain and flooding. The properties of PFOS (high water solubility, negligible vapor pressure, limited sorption to particles, and extraordinary environmental persistence) imply that it would accumulate in water bodies, for example, the Baltic Sea. Thus the concentrations in terrestrial food chains such as the peregrine falcon’s might be temporally closely linked to yearly emissions (mainly to air) with a relatively short response lag. On the other hand, temporal trends studied in marine environments (such as the guillemots) could rather be expected to represent accumulated total emissions with possibly a longer response time especially for ocean current transport to remote regions. Significantly increasing temporal trends (p < 0.001) between 1974 and 2007 were detected also for PFHxS and PFDS in the peregrine falcon eggs. PFHxS and PFDS have both been produced intentionally, but in substantially lower amounts than PFOS. This is mirrored in the considerably lower concentrations of these two PFSAs in biota, compared to PFOS (Figure 2). PFHxS has, however, also been present as an impurity in POSF production. It is thus likely that most PFHxS in the environment originates from the POSF production. PFHxS could therefore be expected to follow the trend of PFOS in environmental samples, which is shown in the peregrine falcon eggs (Figure 2). PFHxS and PFOS concentrations were positively correlated with a correlation coefficient (R 2) of 0.69. PFDS, on the contrary, showed a different pattern with increasing concentrations up to around 2002, resulting in poor correlation of PFDS and PFOS levels (R 2 of 0.059). This discrepancy was also seen in a study on herring gulls where PFOS was leveling off from 1993-2003 whereas PFDS showed an upward slope during the same time (9). A similar observation was also reported in harbor seals from the German Bight (10). This indicates that the PFDS pollution originates from a different source than PFOS and PFHxS. The different trend for PFDS could also be an expression of a possibly higher bioaccumulation potential and elimination half-life for this compound compared to shorter chain PFSAs. Temporal Trends of PFCAs. The PFCAs detected in the falcon eggs all showed exponential increases in concentration during almost the entire studied time, 1974-2007 (Figure 3). However, the rate of increase differed between homologues, ranging from 7.7 to 12% (Table 1). PFUnA, PFDoA, PFTriA, 4086
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and PFPeA (and qualitatively also PFTeA) showed a tendency of leveling off in the latest years, as expressed by the running mean in the respective figures (Figure 3). Log-linear regression of the post 2000 data indicates that concentrations of long chain PFCAs are leveling off or decreasing in the peregrine falcon, in particular for PFCAs of chain length g C11. A similar trend was possibly also shown in Canadian ringed seals (11). The long chain PFCAs have not been intentionally produced, but have been present as impurities (26), or as a result of precursor degradation (27, 28). The slopes for the PFCA time trends (1974-2007) indicate a pattern with steeper increases for odd carbon number PFCAs compared to the adjacent even carbon number homologues (Table 1). This pattern tentatively suggests that sources of exposure differed between odd and even carbon chain homologues. Armitage et al (29) suggested that abiotic and biotic concentrations of C9, C11, and C13 PFCAs predominantly reflect the atmospheric and oceanic transport of direct sources (manufacture and use) while C10 and C12 PFCAs reflect indirect sources (precursor degradation). This is based on the fact that both biotic and atmospheric degradation of fluorotelomer alcohols lead to greater quantities of PFCA homologues with an even number of carbons (27, 28), whereas impurities in the commercial products predominantly consist of odd carbon chain lengths (26). Pattern of PFCA Homologues. A principal component analysis (PCA) of the PFCAs measured in the eggs showed that the percentage contributions of different homologues to total PFCAs have changed in the samples over time (Figure 4). The samples in the plot fall into groups according to sampling decade (1970s, 1980s, or 2000s), and a Hotelling’s t test showed that the samples from the 2000s are significantly different from the samples from the 1970s and 1980s (p < 0.0001). Samples from the 1970s and 1980s are separated, but not significantly different (p < 0.07). Samples from the 1990s were not significantly different from any of the other decades, and were therefore omitted in the plot for better readability. The PCA plot implies changes in PFCA patterns emitted during the respective decades, which could be a result of different usages or modes of production. It further shows that the relative importance of PFTriA has increased, whereas PFDA and PFNA have decreased in relative importance during the past decade. There is no obvious explanation available so far for this change in pattern. Exposure and Toxicological Implications. The present study showed that there are distinct differences in PFAS contamination between peregrine falcon eggs and marine bird eggs, for both PFCAs and PFSAs. The divergences can tentatively be attributed to different routes of exposure. The peregrine falcon is lacking an input source compared to the marine birds. This input source (the ocean) has a long-term storage capacity for PFAS, whereas lifetime of PFAS (or PFAS precursors) in the main media of exposure for the peregrine falcon (air and soil) is limited. This could give an effect of quicker response to changes in emissions as illustrated by the trends for PFOS and PFHxS, which are different from those reported in marine species. Given that emissions of PFUnA and PFTriA are predominantly to water (29), the additional source of waterborne pollution could also result in higher relative concentrations of these PFCAs in marine birds, as observed for guillemot and glaucous gull (6, 20). In the breeding season the falcons in the studied population feed on terrestrial prey such as pigeons, starlings, and thrushes, but also on black headed gulls that have a mixed diet from both terrestrial and aquatic food chains (30). Contaminants found in the eggs of the peregrine falcons could theoretically also represent exposure from overwintering locations along the coasts of Western Europe (see SI Figure S1) where the falcons have a higher proportion of marine species in their diet (31). However, considering the
FIGURE 3. Temporal trends of PFCAs of chain lengths C9-C15 in Swedish peregrine falcon eggs collected between 1974 and 2007. Concentrations are given in ng/g w wt and error bars represent 95% confidence intervals of the geometric mean. Log-linear regression (dashed line, 1974-2007), log-linear regression (dotted line 2000-2007, drawn when statistically significant), and a seven-point running mean smoother (line) are shown. relatively short elimination half-lives of 2-3 weeks reported for PFAS in other bird species (32, 33), exposure from the breeding grounds in Sweden can be assumed to be of greater importance for the PFAS concentrations in eggs. The toxicological implications of PFAS exposure for the peregrine falcon are not known. There is a considerable variability in the effective concentrations reported in toxicological studies. LC50 concentrations from in ovo exposure to PFOS in chicken eggs (Gallus gallus domesticus) of 4900 (34) and 93 000 ng/g egg (35) have been reported, based on reduced hatchability or pippability. The lowest observed adverse effect level (LOAEL) in the study by Molina et al. (34) was found to be 100 ng/g egg, which is in parity with PFOS concentrations in the falcon eggs from recent years. Additionally, a recent toxicological study reported on significant immune alterations and brain asymmetry at injections of 1000 ng PFOS/g egg (36). Alterations of the brain could have severe implications for the peregrine falcon as this species is highly dependent on speed and precision when diving and catching its prey in the air in speeds of over 200 km/h Thus, toxicological effects from PFOS exposure in the Swedish peregrine falcon cannot be ruled out.
FIGURE 4. Principal component analysis (PCA) biplot of proportions of single PFCA homologues (C9-C14) to the sum of PFCAs. Smaller dots show individual samples and larger dots show the geometric mean of the decades 1970s (black), 1980s (gray), and 2000s (white). Ellipses show the Hotelling’s 95% confidence intervals for the mean of the three decades. VOL. 44, NO. 11, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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Acknowledgments We thank Katarina Loso and Mats Hjelmberg for sample preparation, and Thord Fransson for help with the map in the SI. This work was financially supported by the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS project 216-2004-1902).
Supporting Information Available Tables on samples, PFAS concentrations, reference standard compounds, method detection limits (MDL), recoveries, interlab comparison material, and a map of sampling sites and winter locations of the peregrine falcon. This material is available free of charge via the Internet at http://pubs.acs.org.
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