Chemosphere 75 (2009) 1165–1172

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Chemosphere

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Estimated dietary exposure to fluorinated compounds from traditionalfoods among Inuit in Nunavut, Canada

Sonja K. Ostertag a, Brett A. Tague b, Murray M. Humphries a, Sheryl A. Tittlemier b, Hing Man Chan c,*

a Department of Natural Resource Sciences, McGill University, Macdonald Campus, Sainte-Anne-de-Bellevue, Quebec, Canada H9X 3V9b Food Research Division, Health Canada, Ottawa, Ontario, Canada K1A 0K9c Community Health Program, University of Northern British Columbia, 3333 University Way, Prince George, British Columbia, Canada V2N 4Z9

a r t i c l e i n f o a b s t r a c t

Article history:Received 13 November 2008Received in revised form 15 February 2009Accepted 18 February 2009Available online 1 April 2009

Keywords:ArcticPFOSPFOACaribouMarine mammalsTraditional food

0045-6535/$ - see front matter � 2009 Elsevier Ltd. Adoi:10.1016/j.chemosphere.2009.02.053

* Corresponding author. Tel.: +1 250 960 5237; faxE-mail addresses: ostertag@unbc.ca (S.K. Ostertag),

Tague), murray.humphries@mcgill.ca (M.M. Humphrgc.ca (S.A. Tittlemier), lchan@unbc.ca (H.M. Chan).

Increasing evidence shows that persistent organic pollutants such as perfluorinated compounds (PFCs)are found in the Arctic ecosystem and their prevalence is causing human health concerns. The objectiveof this study was to estimate dietary exposure to PFCs among Inuit in northern Canada. Perfluorooctanesulfonate (PFOS), perfluorinated carboxylates (PFCA C7–C11) and fluorotelomer unsaturated carboxylicacids (6:2, 8:2 and 10:2 FTUCA) were measured in 68 traditional foods collected in Nunavut between1997 and 1999. Total PFC concentrations were highest in caribou liver (mean ± standard deviation;6.2 ± 5.5 ng g�1), ringed seal liver (minimum, maximum; 7.7, 10.2 ng g�1), polar bear meat (7.0 ng g�1),and beluga meat (minimum, maximum; 7.0, 5.8 ng g�1). Inuit food intake data from 24-h recalls con-ducted in Nunavut between 1997 and 1999 were used for the calculation of PFC exposure. Mean dailydietary exposure was calculated to range from 210 to 610 ng person�1 (0.6–8.5 ng kg body weight�1)for 754 individuals. Dietary exposure to PFCs was statistically significantly higher in men in the 41–60 year age group (p < 0.05) than younger men (<40 years old) and women from the same age group. Tra-ditional foods contributed a higher percentage to PFC exposure than market foods in all age and gendergroups. Caribou meat contributed 43–75% of daily PFC dietary exposure. Health risks associated withthese estimated exposure levels are minimal based on current toxicological information available fromanimal feeding studies. However, it is important to monitor the concentrations of PFCs in key food itemsgiven that PFCA levels have been found to be increasing in the Canadian Arctic.

� 2009 Elsevier Ltd. All rights reserved.

1. Introduction

Perfluorinated compounds (PFCs) used in such applications ascosmetics, fire fighting foams, and water and grease repellent coat-ings for fabrics and food packaging have been detected in wholeblood and serum of non-occupationally exposed humans in NorthAmerica (Olsen et al., 2003, 2004, 2005; Kubwabo et al., 2004;Calafat et al., 2006a, 2007; Olsen et al., 2007), South America(Calafat et al., 2006b), Europe (Ericson et al., 2007; Fromme et al.,2007) and Asia (Taniyasu et al., 2003; Inoue et al., 2004; Yeunget al., 2006). Sources of human exposure to PFCs have not been fullyelucidated although diet has been suggested as the major route ofexposure in two recent studies (Tittlemier et al., 2007; Trudelet al., 2008).

Previous estimates of dietary exposure to PFCs range fromapproximately 1 ng kg body weight (bw)�1 d�1 (mean perfluorooc-

ll rights reserved.

: +1 250 960 5744.Brett_tague@hc-sc.gc.ca (B.A.ies), Sheryl_tittlemier@hc-sc.

tane sulfonate (PFOS) intake = 0.89 ng kg bw�1) for the populationin Catalonia, Spain (Ericson et al., 2008) to 4 ng kg bw�1 d�1 for thegeneral Canadian population (Tittlemier et al., 2007). Elevatedexposure of PFCs has been associated with the consumption of fishin Polish individuals (Falandysz et al., 2006) and dietary exposureestimates from Spain found fish contributing largely to daily die-tary exposure (Ericson et al., 2008). Furthermore, high intake of pi-lot whale meals by Faorese adolescents was associated with higherserum concentrations of PFOS, perfluorononanoate (PFNA) andperfluorododecanoate (PFDoA) compared to individuals eating lit-tle or no whale (Weihe et al., 2008); therefore, other northern pop-ulations may also be exposed to PFCs due to the consumption ofmarine mammals.

The Inuit diet is composed of foods purchased from local mar-kets (imported foods) and traditional foods obtained from locallyharvested plants and wildlife (Kuhnlein et al., 2000). The consump-tion of traditional foods has been identified as a source of elevatedexposure to mercury, PCBs and radionuclides for Canadian Inuit(Kuhnlein and Chan, 2000) and PFOS, PFCA and PFOS precursors(e.g. perfluorooctanesulfonamide derivatives) were recently de-tected in wildlife and fish species in the Canadian Arctic consumed

1166 S.K. Ostertag et al. / Chemosphere 75 (2009) 1165–1172

by Inuit (Giesy and Kannan, 2001; Tomy et al., 2004; Martin et al.,2004a; Kannan et al., 2005; Smithwick et al., 2005a,b, 2006; Buttet al., 2007a,b). Dietary surveys conducted in the Canadian Arcticindicate that the traditional diet of Inuit is largely composed of car-ibou meat and marine mammal meat (Kuhnlein et al., 2000). How-ever, most studies have measured PFCs in liver and blood samplesfrom marine mammals, fish and birds in the Arctic for monitoringpurposes (Giesy and Kannan, 2001; Tomy et al., 2004; Martin et al.,2004a; Kannan et al., 2005; Smithwick et al., 2005a,b, 2006; Buttet al., 2007a,b), therefore these data were unsuitable for the esti-mation of dietary exposure to PFCs among Inuit from the consump-tion of traditional foods.

In this paper, we present the results of the analysis of PFCs andfluorotelomer unsaturated carboxylic acids (FTUCA) in archivedtraditional foods from Nunavut and estimate daily dietary expo-sure to these compounds for Inuit men and women in the late1990s. Dietary exposure estimates were based on quantities ofmarket and traditional foods consumed and concentrations of PFCsmeasured in traditional foods collected in Nunavut and previouslyanalyzed composite samples of market and restaurant foods fromHealth Canada’s Total Diet Study (TDS) (Ostertag, 2008). Analyzingfoods prepared as per consumption and from their packaging isimportant for estimating dietary exposure to PFCs; packagingwas associated with the contamination of foods with PFOA (Begleyet al., 2005) and PFC precursors (Tittlemier et al., 2006), and cook-ing fish reduced the concentration of PFCs by more than 50% (DelGobbo et al., 2008). There are no human consumption guidelinesfor chronic exposure to PFOS and PFCA established by the WorldHealth Organization or Health Canada. Therefore, a preliminaryhealth risk assessment was carried out based on the provisionaltolerable intake (pTDI) set by the German Drinking Water Commis-sion (Drinking Water Commission, 2006) and toxicological end-points from animal feeding studies (Thomford, 2002; Butenhoffet al., 2004).

2. Materials and methods

2.1. Standards, reagents and materials

Eleven perfluorinated and fluorotelomer compounds (pur-ity > 95%) were used as standards: perfluoroheptanoic acid(Aldrich, Oakville, ON, Canada), perfluoroctanoic acid (WellingtonLaboratories, Guelph, ON, Canada), perfluorononanoic acid (Al-drich), perfluorodecanoic acid (Aldrich), perfluoroundecanoic acid(Aldrich), perfluorododecanoic acid (Aldrich), perfluorotetradeca-noic acid (Aldrich), L-perfluorooctane sulfonate (Wellington), 2H-perfluoro-2-dodecenoic acid (Wellington), 2H-perfluoro-2-dece-noic acid (Wellington) and 2H-perfluoro-2-octenoic acid (Welling-ton). Stable isotope-labelled perfluorinated and fluorotelomercompounds were used as recovery and internal performance stan-dards: 1,2-13C perfluorooctanoic acid (Perkin–Elmer, Boston, MA,USA; 98% chemical purity, 99% isotopic purity), perfluoro-n-[1,2,3,4-13C4] octanoic acid (Wellington), 1,2-13C perfluoronona-noic acid (3 M, 95% chemical purity, 99% isotopic purity), 13C5 per-fluorononanoic acid (Wellington), 1,2-13C perfluorodecanoic acid(Wellington Laboratories, 98% chemical purity, >99% isotopic pur-ity), sodium 1,2,3,4-13C perfluorooctane sulfonate (Wellington,98% chemical purity, >99% isotopic purity), L-18O2 PFOS (RTI Inter-national, Research Triangle Park, NC, USA), 2H-perfluoro-[1,2-13C2]-2-octenoic acid (Wellington), 2H-perfluoro-[1,2-13C2]-2-decenoic acid (Wellington) and 2H-perfluoro-[1,2-13C2]-2-dodece-noic acid (Wellington). All water used in the method was Milli-Qpurified (Millipore, Billerica, MA, USA) and passed through a glasscolumn containing Amberlite XAD-7 resin (Aldrich) to remove anypossible perfluorinated contaminants. Methanol (MeOH; Optima,FisherScientific), ammonium hydroxide (Baker analyzed, 29% pur-

ity), glacial acetic acid (FisherScientific HPLC grade) and anhydroussodium acetate were used without extra purification. Weak anionexchange (WAX) cartridges (Oasis�Wax, 6 cc, 150 mg, 30 lm) so-lid-phase extraction (SPE) cartridges were purchased from Waters(Milford, MA).

2.2. Sample description

Locally harvested animal and plant-derived foods samples werecollected in Nunavut between 1997 and 1998 for the study ‘Assess-ment of Dietary Benefit/Risk in Inuit Communities’ (Kuhnlein et al.,2000). In total, 68 archived traditional food samples were analyzedand sample details are presented in Tables 1 and 2. All sampleswere stored in chemically cleaned polypropylene NalgeneTM con-tainers and lids at �20 �C following homogenization. Food sampleswere selected for analysis to match the animal (species, tissue andpreparation methods) cited in 24-h recalls conducted in Nunavut(Kuhnlein et al., 2000). Samples were primarily collected fromChesterfield Inlet, Igloolik, Pond Inlet and Qiqiktarjuaq in Nunavut.Frequently consumed foods and foods expected to contain greaterconcentrations of PFCs such as organ meats and blood, and tissuefrom animals at high trophic positions were analyzed. Another65 samples from the Health Canada TDS collected in Whitehorse,YT, were analyzed previously and represent foods frequently con-sumed by Inuit (Kuhnlein et al., 2004), including coffee, tea, bread,potatoes and meat (chicken, pork, beef and processed meats). Theresults from the analysis of PFCs in the TDS samples are presentedelsewhere (Ostertag, 2008).

2.3. Analytical method

Identical methods were used for the extraction, clean-up andanalysis of PFCs in traditional foods and TDS samples. Sampleswere thawed at room temperature and one gram of cooked ordried food, or 2 g raw food (liquid or solid) was placed in metha-nol-rinsed polypropylene centrifuge tubes. The difference in sam-ple aliquot size was due to the poor yield of supernatant for 2 gof low moisture samples following methanol extraction (data notshown). The extraction of PFCA (C7–C11), PFOS and FTUCA was car-ried out with a methanol extraction modified from the method de-scribed by Tittlemier et al. (2005) followed by a solid-phaseextraction described by Taniyasu et al. (2005). Each sample wasspiked with 5000 pg recovery standard (50 lL of 100 pg lL�1 solu-tion made up of 13C4 PFOA, 13C2 PFNA and 13C4 PFOS) and 4 mLmethanol was added immediately to all samples except liquidsamples. Liquid samples were freeze-dried for 6 h (Flexi-Dry MPmicroprocessor controlled bench top lyophilizer; FTS Systems,Inc., Stone Ridge, NY) prior to the addition of 4 mL methanol. Themethanol extraction steps were as follows: tubes were capped,vortexed and placed on an orbital shaker at 200 rpm, 25 �C for4 h, the samples were then vortexed and centrifuged at 667g,10 �C for 10 min and the supernatants were transferred to pre-cleaned polypropylene centrifuge tubes. Two more extractionswere carried out under the following conditions: 2 mL methanolwere added to the sample, vortexed and placed on the orbital sha-ker for 10 min and centrifuged (same conditions as above). Super-natants were combined, vortexed and dried to 0.5 mL under agentle stream of nitrogen gas in a water bath at 37 �C.

Samples were diluted to 50 mL with Milli-Q water prior to SPE.WAX cartridges were conditioned with 4 mL 0.1% NH4OH in meth-anol, 4 mL methanol and 4 mL water (2 drops per second) and sam-ples were loaded and passed through the cartridge (1 drop persecond), followed by 4 mL of 25 mM sodium acetate buffer (pH4) to remove biomolecules and lipids and to improve adsorptionof target compounds (Taniyasu et al., 2005). Elution was carriedout with 4 mL methanol followed by 4 mL 0.1% NH4OH in metha-

Table 1Concentration of PFCs in aquatic traditional foods collected between 1997 and 1999 in Nunavut.

Food Part and preparation N PFOS PFOA PFNA PFDA PFUA Sum

Ringed Seal Liver Raw 2 3.8, 7.6 0.3, <0.2 1.9, 2.1 0.5, <0.7 1.2, 0.6 7.7, 10.2Blood Raw 3 2.9 ± 2.1 0.1 ± 0.1 1.2 ± 0.3 0.2 ± 0.2 0.6 ± 0.6 5.0 ± 2.9Meat Boiled 1 0.5 <0.5 0.5 <0.2 <0.2 1.0

Raw 3 0.2 ± 0.3 <0.2 0.9 ± 0.6 <0.3 <0.4 1.1 ± 0.5Blubber Raw 2 0.1, <0.1 <0.2 0.2, <0.2 0.1, <0.2 0.2, <0.1 0.6, nd

Polar Bear Meat Frozen 1 4.0 <0.3 0.8 0.6 1.6 7.0Beluga Blubber Raw 1 1.5 <0.2 0.4 0.3 0.7 3.1

Meat Dried 2 3.6, 1.6 <0.3 0.6, 0.9 0.7, 0.8 2.0, 2.5 6.9, 5.8Muktuk Raw 1 0.4 <0.3 <0.4 <0.4 0.8 1.2

Narwhal Blubber Raw 1 0.2 <0.1 <0.1 <0.2 0.2 0.4Muktuk Raw 2 <0.4 <0.3 0.5, 0.5 <0.4 <0.4 0.5, 0.5Muktuk Frozen 2 1.6, 0.4 <0.2 <0.4 <0.2, 0.3 <0.4, 0.3 1.6, 1.0

Bearded Seal Intestine Boiled 2 0.5, 0.6 <0.6 0.3, 1.2 0.2, <0.4 0.2, 0.4 1.2, 2.2Meat Boiled 1 0.2 <0.2 <0.3 <0.2 <0.2 0.2

Walrus Blubber Aged 1 <0.1 <0.1 0.4 0.2 <0.1 0.6Kauk Raw 1 0.2 <0.2 0.6 <0.2 <0.3 0.8Meat Raw 2 <0.3 <0.3 0.6, 0.8 0.2, <0.3 <0.2 0.8, 0.8

Aged 1 <0.2 <0.2 <0.3 <0.2 <0.2 ndEider Duck Whole Boiled 1 1.6 0.4 <0.1 0.6 0.3 2.8Black Duck Meat Boiled 1 0.3 <0.2 <0.3 0.3 0.1 0.7Arctic Char Whole Raw 3 <0.5, <0.2, 0.2 ± 0.3 0.1 ± 0.1 <0.5, 0.3 ± 0.4Lake Trout Whole Raw 2 0.4, 0.1 <0.1 <0.3 0.2, <0.2 0.1, 0.1 0.7, 0.2Seaweed Whole Raw 1 <0.2 <0.1 <0.3 0.1 <0.2 0.1Clams Whole Raw 1 <0.2 <0.4 0.5 <0.2 <0.2 0.5

Table 2Concentration of PFCs in terrestrial traditional foods collected between 1997 and 1999 in Nunavut.

Food Part and preparation N PFOS PFOA PFNA PFDA PFUA Sum

Caribou Liver Baked 1 5.0 0.7 1.6 0.6 1.1 9.0Raw 3 2.7 ± 2.3 0.1 ± 0.1 2.0 ± 1.7 0.7 ± 0.7 0.7 ± 0.8 6.2 ± 5.5

Meat Boiled 2 <0.3, 0.1 <0.1 0.8, <0.1 <0.2 <0.5 0.8, 0.1Dried 2 <0.4, <0.4 <0.9, 1.0 <0.8 <0.2 nd, 1.0Raw 2 <0.2 <0.3 0.3, 0.3 <0.2 <0.2 0.3, 0.3Roasted 1 <0.2 <0.3 1.0 0.4 <0.6 1.4

Bone marrow Boiled 1 0.2 <0.2 0.6 0.2 0.2 1.1Heart, blood Raw 1 0.2 <0.2 0.8 0.2 <0.3 1.2Fat Raw 1 <0.2 <0.2 <0.3 <0.2 <0.2 ndKidneys Raw 2 0.1, 0.1 <0.2 0.2, 0.2 <0.2 <0.2 0.3, 0.3

Boiled 1 <0.2 <0.2 <0.3 <0.2 <0.2 ndStomach Raw 1 0.1 0.8 0.1 <0.2 <0.2 1.0Tongue Raw 3 0.2 ± 0.2 0.0 ± 0.1 0.6 ± 0.6 <0.2 <0.2 0.8 ± 0.8

Ptarmigan Whole Raw 3 <0.2 <0.2 <0.6 0.0 ± 0.1 <0.2 0.2 ± 0.02Arctic Hare Meat Raw 2 <0.2 <0.1 <0.3, 0.2 <0.2, 0.2 <0.2 0.0, 0.3Snow Goose Meat Raw 1 <0.2 <0.1 1.2 <0.2 <0.2 1.2Berries Whole Raw 3 <0.1 <0.1 <0.3 0.1 ± 0.1 <0.1 0.1 ± 0.1

S.K. Ostertag et al. / Chemosphere 75 (2009) 1165–1172 1167

nol (1 drop per second) and the eluate was dried to 0.5 mL under agentle stream of nitrogen. The eluate was vortexed, a 250 lL ali-quot was taken, 20 lL of the internal performance standard solu-tion (concentration of 100 pg lL�1 for each of the followingstandards: 13C2 PFOA, 13C PFDA, 13C5PFNA, 13C FTUCA and L-18O2

PFOS) and 230 lL water were added. Samples were vortex-mixedand centrifuged at 2200 g for ten minutes and approximately450 lL was transferred to a polypropylene autosampler vial,capped and stored at 4 �C until analysis.

2.4. Instrumental analysis

Samples were analyzed using HPLC-ESI-MS/MS with methodssimilar to those reported by Tittlemier et al. (2007). In brief, sam-ples (10 lL injection) were chromatographed on a 2.1 � 50 mmGenesis C18 analytical column (Jones Chromatography Ltd., Hen-goed, Mid Glamorgan, UK) and C18 guard column (4 mm � 2.0 mmi.d.; Phenomenax, Torrance, CA) installed on an HP 1100 binarypump high performance liquid chromatograph (Agilent, Palo Alto,CA). The mobile phase solutions were 5 mM ammonium formate

in Barnstead Diamond water (18 MX-cm) (solution A) and a 1:1(v/v) solution of acetonitrile/methanol (solvent B). PFCs were chro-matographically resolved using the following gradient program:40% B at 0.200 mL min�1 for 1 min, 45% B over 4 min, increasingto 70% B over 8 min, 75% B over 2 min, and 95% B over 4 min andthen held at 95% B for 0.1 min. The column was then flushed with40% B for 10.9 min. The liquid chromatograph was connected to aVG Quattro II triple quadrupole mass spectrometer (Micromass,Manchester, UK). Analytes and the transitions monitored are pro-vided in Table 3. Operational parameters for the mass spectrome-ter were as follows: capillary voltage 2.0 kV, source temperature140 �C, and nebulizer and drying gas (N2) flow rates 20 L h�1 and350 L h�1, respectively. The collision gas was nitrogen at2.0 � 10�3 mbar and the mass resolution was set at 1.2 mass unitsat the base for both mass analyzers.

2.5. Quantitation and QA/QC

Target analytes were considered to be positively identified iftheir retention time was within 2.5% of the standard retention

Table 3Instrument performance standards used to account for matrix effects for analytes and MS/MS multiple reaction monitoring parameters (first transition listed was used forquantitation).

Analyte Performance standard Mass transition Cone voltage Collision energy

Perfluoroheptanoate (PFHpA) 1,2-13C perfluorooctanoate 362.9 ? 318.8 10 15Perfluorooctanoate (PFOA) 1,2-13C perfluorooctanoate 412.9 ? 368.8 10 15

412.9 ? 168.8Perfluorononanoate (PFNA) 1,2,3,4,5-13C perfluorononanoate 462.8 ? 418.8 12 18

462.8 ? 218.8 16 18Perfluorodecenoate (PFDA) 1,2-13C perfluorodecanoate 512.8 ? 468.9 15 18

512.8 ? 218.9 15 18Perfluoroundecanoate (PFUA) 1,2-13C perfluorodecanoate 562.9 ? 518.9 15 15

562.9 ? 268.8Perfluorooctane sulfonate (PFOS) L-18O2 perfluorooctane sulfonate 498.9 ? 98.9 50 60

498.9 ? 79.96:2 Fluorotelomer unsaturated carboxylate (6:2 FTUCA) 2H-Perfluoro-[1,2-13C2]-2-octenoate 356.9 ? 292.9 15 178:2 Fluorotelomer unsaturated carboxylate (8:2 FTUCA) 2H-Perfluoro-[1,2-13C2]-2-decenoate 457 ? 392.9 18 2010:2 Fluorotelomer unsaturated carboxylate (10:2 FTUCA) 2H-Perfluoro-[1,2-13C2]-2-dodecenoate 557 ? 493 20 25

1168 S.K. Ostertag et al. / Chemosphere 75 (2009) 1165–1172

time, the signal-to-noise ratio was greater than three and the con-firmation mass transition was present (when applicable). Relativeresponse factors were calculated as a ratio of the peak area of thetarget analyte and corresponding stable isotope-labelled internalperformance standard (presented in Table 3). Quantitation wasbased on an external five-point calibration curve made up in meth-anol and water (1:1 ratio) and the curve for each analyte consis-tently had an r2 value >0.98. Concentrations were not recovery-corrected. The IDL was estimated for each sample as the concentra-tion for which the corresponding peak had a signal-to-noise ratioof 3. Method detection limits (MDL) were considered as threetimes the standard deviation of the blanks plus the IDL dividedby the weight of sample (Smithwick et al., 2005a). If the blankwas below the IDL, the MDL was estimated as three times thestandard deviation of the lowest concentration standard of thecalibration curve (Gomez-Taylor et al., 2003). The LOQ was deter-mined as three times the MDL. QA/QC steps included methanollaboratory blanks and fortified matrix samples (homogenizedraw ground beef fortified with 50 lL of a 100 pg lL�1 standardsolution of target analytes) with each batch of samples (7–12samples per batch) and the addition of stable isotope-labelledrecovery internal standards and internal performance standardsto each sample.

2.6. Dietary exposure estimate and statistical analyses

Human ethics approval was obtained to carry out secondarydata analysis with archived food samples and dietary intakeinformation collected in Nunavut from the Ethics Review Boardof McGill University. Dietary exposure to PFCs was estimated usingconcentration data from traditional foods measured in this studyand data from the analysis of 65 composite samples from HealthCanada’s 1998 Total Diet Study (TDS) measured previously (Oster-tag, 2008). Concentration data for traditional food and TDS sampleswere matched with intake data from 24-h recalls conducted inNunavut between 1997 and 1999 (Kuhnlein et al., 2000). Tradi-tional foods analyzed were matched with intake data based onthe species, part and preparation of foods consumed; TDS sampleswere matched based on the contents and preparation of foods con-sumed. PFC intake from individual foods was summed for eachrespondent to the 24-h recall; mean and 95th percentile of PFCexposure were then estimated for four age categories of men andwomen (13–19, 20–40, 41–60, older than 61 years old). Two die-tary exposure estimates were calculated: a conservative estimate(<MDL = 0) and a more cautious estimate (<MDL = 0.5 * MDL). Die-tary intake was adjusted for the weight of individuals; meanweights for Alaskan Eskimos in 1994 (Risica et al., 2000) were used

for age groups over 20 years old (64.2 kg for females and 71.6 kgfor males) and the weights for American youth (Institute of Medi-cine, 2005) were used for Inuit youth (57 kg for females and 64 kgfor males).

A one-way ANOVA was carried out to identify whether age andgender were statistically significantly associated with PFC expo-sure. Pair-wise tests were run with adjustments for multiple com-parisons using Bonferonni tests to compare mean exposure levelsbetween age groups for each gender, and between genders in eachage group. Maximum dietary exposure to PFCs was assessed by cal-culating the 95th percentiles for PFOS and combined PFCA/FTUCAintake for each age and gender group (adjusted for bw). All statis-tical analyses were carried out using SAS (Cary, NC v.9.1).

Health risks posed by dietary exposure to PFCs among Inuit wasassessed using the mean exposure and the 95th percentile of expo-sure based on the cautious exposure estimates (<MDL = 0.5 * MDL).Hazard indices were calculated by dividing the estimated PFOS andcombined PFCA/FTUCA exposure by the pTDI (100 ng kg bw d�1 forboth PFOS and PFOA) determined by the German Drinking WaterCommission (Drinking Water Commission, 2006). Margins of expo-sure (MOE) were calculated for PFOS and PFCA/FTUCA; PFCA/FTUCAexposure estimates were divided by the benchmark dose levelcalculated to elicit a response in 10% of the study population(BMDL10) for PFOA (600000 ng kg bw�1 d�1) (Butenhoff et al.,2004) and PFOS exposure estimates were divided by the lowestobservable effects level (LOEL) for PFOS (30000 ng kg bw�1 d�1)(Thomford, 2002).

3. Results

3.1. Quality assurance and quality control

Six fortified ground beef samples were analyzed to assess therecoveries of target analytes. The following recoveries (±standarddeviations) were calculated for FTUCA: 64 ± 8% (6:2 FTUCA),74 ± 8% (8:2 FTUCA) and 77 ± 9% (10:2 FTUCA). PFCA recoverieswere: 70 ± 6% (PFHpA), 110 ± 5% (PFOA), 85 ± 7% (PFNA), 68 ± 2%(PFDA), 49 ± 6% (PFUA). Mean recovery for PFOS was 55 ± 10%.Recoveries of the internal recovery standards, 13C4 PFOA, 13C2 PFNAand 13C4 PFOS, were calculated for all samples (n = 68) and were88 ± 16%, 110 ± 43% and 99 ± 27% respectively. Method blankswere free of detectable concentrations of all FTUCAs, PFOS andPFCAs longer than PFOA. The concentrations of PFHpA and PFOAin method blanks were converted to concentrations for 2 g of tissueand mean concentrations (±standard deviations) were 0.16 ± 0.03and 0.02 ± 0.03 ng g�1, respectively. Mean MDL (±standard devia-tion) for the analytes of interest were: 0.33 ± 0.14 (6:2 FTUCA),

0

10

20

30

40

50

60

70

80

90

100

<20 20-40 41-60 >60 <20 20-40 41-60 >60

95th percentile (<MDL = 0.5*MDL) mean (<MDL = 0.5* MDL)Age, Gender and Estimate Used

Expo

sure

(ng/

kg b

.w./d

ay)

Total PFCA and FTUCA ExposurePFOS Exposure

Fig. 2. Estimated daily dietary exposure to PFOS and combined PFCA/FTUCAexposure among Inuit women. Mean and 95th percentiles of exposure arepresented based on exposure estimates in which <MDL = 0.5 * MDL.

S.K. Ostertag et al. / Chemosphere 75 (2009) 1165–1172 1169

0.18 ± 0.07 (8:2 FTUCA), 0.13 ± 0.15 (10:2 FTUCA), 0.24 ± 0.19(PFHpA), 0.19 ± 0.12 (PFOA), 0.31 ± 0.25 (PFNA), 0.20 ± 0.16 (PFDA),0.24 ± 0.18 (PFUA) and 0.15 ± 0.14 (PFOS).

3.2. Concentrations in traditional foods

The concentration of PFCs measured in the traditional foodsamples are presented in Tables 1 and 2. PFCs were detected in61 of the 68 traditional food samples analyzed. Highest total PFCconcentrations were detected in ringed seal liver, caribou liver,ringed seal blood, polar bear meat and beluga meat and total PFCconcentrations were below 1 ng g�1 in 41 traditional foods ana-lyzed. PFNA and PFOS were detected most frequently (44 and 39samples, respectively) followed by PFDA (28 samples) and PFUA(23 samples). PFOA was rarely detected in traditional foods (onlyin nine samples). PFHpA and FTUCA were not detected in any sam-ple analyzed. The sum of PFCA exceeded the concentration of PFOSin 51 of 68 traditional foods analyzed.

3.3. Effects of preparation on PFC concentration

An analysis of the effects of preparation on the concentration ofPFCs was not possible due to the low sample size for traditionalfood samples that had undergone different preparation steps. Dif-ferences in PFC concentrations based on preparation were incon-sistent in caribou and ringed seal meat, likely due to the smallnumber of samples analyzed for the different preparations (boiled,dried, roasted and raw). The baked caribou liver sample (n = 1) hada higher concentration of PFOS (5.0 ng kg�1) and PFOA(0.7 ng kg�1) than raw samples (PFOS: 2.7 ± 2.3 ng kg�1, PFOA:0.1 ± 0.1 ng kg�1).

3.4. Inuit dietary exposure estimates and risk assessment

PFC exposure estimates from the consumption of market andtraditional foods are presented in Figs. 1 and 2. Mean exposure ran-ged from 0.6 to 6.4 ng kg bw�1 d�1 for women (conservative ap-proach, <MDL = 0), and 49.9–65.5 ng kg bw�1 d�1 (cautiousapproach, <MDL = 0.5 * MDL). In Inuit men, estimated mean PFCexposure ranged from 3.3 to 8.5 ng kg bw�1 d�1 (conservative ap-proach) and 44.3–71.5 ng kg bw�1 d�1 (cautious approach). Theconservative dietary exposure estimates (<MDL = 0) indicated thatmean daily exposure to PFCs was not statistically significantly dif-ferent between women of different age groups. However, Inuit

0

10

20

30

40

50

60

70

80

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100

<20 20-40 41-60 >60 <20 20-40 41-60 >60

95th percentile (<MDL = 0.5*MDL) mean (0.5* MDL)

Age, Gender and Estimate Used

Expo

sure

(ng/

kg b

.w./d

ay)

Total PFCA and FTUCA ExposurePFOS Exposure

Fig. 1. Estimated daily dietary exposure to PFOS and combined PFCA/FTUCAexposure among Inuit men. Mean and 95th percentiles of exposure are presentedbased on exposure estimates in which <MDL = 0.5 * MDL.

men in the 41–60 year age group had statistically significantlyhigher PFC exposure (p < 0.05) than younger men (<20 years old,20–40 years old) and women from the same age group (conserva-tive approach).

Mean daily exposure to PFOS ranged from 0.2 to 2.4 ng kg bw�1

(conservative approach) and 2.6–3.8 ng kg bw�1 (cautious ap-proach). Mean daily exposure to combined PFCA/FTUCA rangedfrom 3.1 to 6.2 ng kg bw�1 (conservative approach) and 41.7–67.8 ng kg bw�1 (cautious approach). The 95th percentile for die-tary exposure to PFCs (cautious approach) was 4.3 ng kg bw�1 d�1

for PFOS and 78.1 ng kg bw�1 d�1 for combined PFCA/FTUCA. Thecontribution of individual analytes to total PFCA/FTUCA exposure(conservative approach) was as follows: PFNA (50–84%), PFDA(10–18%), PFOA (1–15%), PFUA and PFHpA (1–13%) and 6:2 FTUCA(less than 2%). With our conservative dietary exposure estimate,FTUCA exposure was due to the presence of 6:2 FTUCA in compos-ite samples of market foods from the Total Diet Study (data notshown).

The hazard indices for dietary exposure to PFOS and combinedPFCA/FTUCA were less than one for PFOS (0.03–0.04) and com-bined PFCA/FTUCA (0.49–0.78). The margin of exposure exceeded1000 for PFOS and for PFCA/FTUCA (range: 7687–12358) for allexposure estimates using the BMDL10 for PFOA (600000ng kg bw d�1) and LOEL (30000 ng kg bw d�1).

3.5. Sources of exposure

Traditional foods contributed a higher percentage to PFC dietaryexposure than market foods as a dietary source of PFCs for Inuit inall age and gender groups (conservative approach, <MDL = 0)(Fig. 3). PFC intake from the consumption of traditional foods dou-bled and increased from the consumption of market foods by anorder of magnitude with the cautious exposure estimates(<MDL = 0.5 * MDL) (see Fig. 4). Based on the conservative expo-sure estimates, primary sources of exposure to PFCs were cariboumeat, Arctic char, cookies and beluga muktuk. In general, caribou(predominantly meat), beluga (predominantly muktuk (skin andfat)) and Arctic char contributed most to dietary exposure for Inuit,with caribou meat contributing 43–75% of daily PFC dietary expo-sure. Elevated dietary exposure to PFCs in males (41–60 years old)was associated with the consumption of a larger number of tradi-tional food species, including caribou liver and bearded seal intes-tine than other age and gender groups. Caribou liver (450 g) wasonly consumed by one man between 41 and 60 years of age. Over-all, Inuit with higher PFC exposure consumed large quantities of

Fig. 3. Sources of PFC exposure for Inuit males and females, given as the exposure to PFCs from each food as a percentage of mean daily exposure for each age-gender group.Foods that did not contribute at least 5% to mean daily PFC exposure to at least one gender/age group are not shown. Exposure was based on the substitution of zero for valuesbelow the MDL.

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

males females males females

0=LDM<LDM*5.0=LDM<Age, Gender and Substitution Used (values < MDL)

Mea

n D

aily

PFC

Exp

osur

e (n

g/da

y)

Traditional FoodsMarket Foods

Fig. 4. A comparison of the mean contribution of market and traditional foods todietary exposure to PFCs; values below MDL were substituted with zero or0.5 * MDL.

1170 S.K. Ostertag et al. / Chemosphere 75 (2009) 1165–1172

traditional foods (i.e. ringed seal muscle and broth; beluga muktuk,blubber and caribou meat) or consumed one traditional food with ahigher concentration of PFCs (i.e. caribou liver).

4. Discussion

4.1. Concentrations of PFCs in traditional foods

In marine mammals, total PFC concentrations were greatest inthe meat of animals at higher trophic levels (i.e. polar bear, beluga)and in liver (i.e. caribou and ringed seal), which is consistent withobservations that PFOS and PFOA biomagnify in aquatic food webs(Tomy et al., 2004; Martin et al., 2004a,b) and accumulate in liverand blood (Johnson et al., 1979; Vanden Heuvel et al., 1991). PFCshave been previously measured in ringed seal liver, beluga liverand clams from the Canadian Arctic (Tomy et al., 2004; Martinet al., 2004a). The concentrations of PFOS, PFNA and PFUA weresimilar in ringed seal liver samples analyzed by Martin et al.(2004a) and our study. PFDA was detected at a lower concentration

in ringed seal liver samples in our study (<0.7 and 0.5 ng g�1) com-pared to levels previously measured (0.98–2.8 ng g�1, n = 19) (Mar-tin et al., 2004a). PFOS was not detected in the one clam sampleanalyzed in our study, however, 0.28 ± 0.09 ng g�1 PFOS was mea-sured in clams analyzed by Tomy et al. (2004).

PFCs were detected in nearly every traditional food sample ana-lyzed, which was in contrast to the results from the analysis ofstore-bought foods in Canada, Spain and the UK (Mortimer et al.,2006; Tittlemier et al., 2006, 2007; Ericson et al., 2008). Levels ofPFCs in store-bought meats (Tittlemier et al., 2007) were similarto levels detected in ringed seal and caribou meat in this study(i.e. below 5 ng g�1). Levels of PFCs in liver (e.g. ringed seal and car-ibou) and higher trophic level animal meat (e.g. polar bear, beluga)were higher than levels found in most store-bought foods in Can-ada (Tittlemier et al., 2007).

4.2. Dietary exposure estimates

The conservative dietary exposure estimates from this studyranged from 0.2 to 2.4 ng kg bw�1 d�1 for PFOS, 0.1–0.5ng kg bw�1 d�1 for PFOA and 1.5–4.4 ng kg bw�1 d�1 for PFNA.Overall, these results were comparable to previously publishedexposure estimates. Dietary exposure estimates for PFOS were1.07 ng kg bw�1 d�1 (Ericson et al., 2007), 1.4 ng kg bw�1 d�1

(Fromme et al., 2007) and 1.8 ng kg bw�1 d�1 (Tittlemier et al.,2007). Dietary exposure to PFOA was estimated to range from1.1 ng kg bw�1 d�1 for the Canadian population (Tittlemier et al.,2007) and 2.9 ng kg bw�1 d�1 for the German population (Frommeet al., 2007). PFNA exposure estimates were only available for theCanadian population (1.1 ng kg bw�1 d�1), given that PFNA wasnot detected in the duplicate diet study (Fromme et al., 2007) ormarket foods collected in Catalonia, Spain (Ericson et al., 2008).These results suggest that the consumption of locally harvestedanimals leads to a different PFCA exposure profile among Inuit inNunavut compared to other populations. This may be due to thedetection of PFNA at higher concentrations than PFOA in bothaquatic and terrestrial Arctic species. In the study by Tittlemieret al. (2007), the concentration of PFNA exceeded that of PFOA inonly one sample (beef steak: 4.4 ng g�1), and PFOA was detectedmore frequently than PFNA in the samples analyzed. PFNA may

S.K. Ostertag et al. / Chemosphere 75 (2009) 1165–1172 1171

have been detected less frequently than PFOA in the study byTittlemier et al. (2007) due to the higher LOD for PFNA (1 ng g�1)compared to PFOA (0.4–2.0 ng g�1).

4.3. Significance of dietary exposure to PFCs

Dietary exposure estimates derived from 24-h dietary recallsmay be used at the population level to address average intake fora large group of individuals (Beaton, 1992). Substituting zero forvalues below the MDL provided an underestimate of actual dietaryexposure to PFCs for Inuit. However, given that only 8 of 65 marketfoods analyzed had detectable concentrations of PFCs, substitutinghalf of the MDL for concentrations below the MDL likely led to anoverestimate of exposure. The use of the cautious dietary exposureestimates in our risk assessment resulted in hazard indices for bothPFOS and PFCA/FTUCA that were less than one, indicating that in a‘‘worst-case-scenario”, the Inuit population in Nunavut would havelower levels of dietary exposure to PFCs than the pTDI. Comparingthe estimated PFC exposure to toxicological endpoints indicatedthat the cautious exposure estimates (mean and 95th percentiles)were at least three orders of magnitude lower than doses associ-ated with adverse outcomes in laboratory feeding trials. Therefore,dietary exposure to PFCs is of minimal health concern for the Inuitpopulation, which is consistent with dietary exposure risk assess-ments for other populations (Fromme et al., 2007; Tittlemieret al., 2007; Ericson et al., 2008).

The contamination of the Arctic with PFCs has resulted in die-tary exposure of Inuit in Nunavut to PFCs at levels comparable tothe Canadian and European populations. Although our data suggestthat Inuit exposure to PFCs is lower than that considered as a con-cern for public health, our study does not fully address exposure toPFCA and PFOS precursors, which are expected to be present inboth market and traditional foods (Tomy et al., 2004; Tittlemieret al., 2006; D’Eon and Mabury, 2007). The use of an internal doseof PFCs (i.e. concentration of PFCs in blood or serum) would reduceuncertainties associated with extrapolating animal exposure datato humans and would also take into account exposure to PFOSand PFCA precursors. Greater efforts to understand the sources ofPFCAs and PFC precursors to the Arctic and to reduce these inputsare necessary to reduce Inuit exposure to PFCs. The PFC exposureestimates derived in this study do not indicate that dietary expo-sure to PFOS, PFCA or FTUCA poses any immediate health concern.Communication of health risk associated with PFC exposure shouldbe undertaken in the context of recognizing the importance of tra-ditional foods in Inuit culture and diet.

Acknowledgements

Funding for this work was provided by the Northern Contami-nants Program, Health Canada, NSERC and ArcticNet. We thankKaren Pepper, Cathie Menard, and Donna Leggee for laboratorysupport and Rula Soueida for assistance with statistical analyses.

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