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

Chemosphere 75 (2009) 1165–1172

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Estimated dietary exposure to fluorinated compounds from traditional foods 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 3V9 Food Research Division, Health Canada, Ottawa, Ontario, Canada K1A 0K9 c Community Health Program, University of Northern British Columbia, 3333 University Way, Prince George, British Columbia, Canada V2N 4Z9 b

a r t i c l e

i n f o

Article history: Received 13 November 2008 Received in revised form 15 February 2009 Accepted 18 February 2009 Available online 1 April 2009 Keywords: Arctic PFOS PFOA Caribou Marine mammals Traditional food

a b s t r a c t 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 objective of this study was to estimate dietary exposure to PFCs among Inuit in northern Canada. Perfluorooctane sulfonate (PFOS), perfluorinated carboxylates (PFCA C7–C11) and fluorotelomer unsaturated carboxylic acids (6:2, 8:2 and 10:2 FTUCA) were measured in 68 traditional foods collected in Nunavut between 1997 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 conducted in Nunavut between 1997 and 1999 were used for the calculation of PFC exposure. Mean daily dietary 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. Traditional foods contributed a higher percentage to PFC exposure than market foods in all age and gender groups. Caribou meat contributed 43–75% of daily PFC dietary exposure. Health risks associated with these estimated exposure levels are minimal based on current toxicological information available from animal feeding studies. However, it is important to monitor the concentrations of PFCs in key food items given that PFCA levels have been found to be increasing in the Canadian Arctic. Ó 2009 Elsevier Ltd. All rights reserved.

1. Introduction Perfluorinated compounds (PFCs) used in such applications as cosmetics, fire fighting foams, and water and grease repellent coatings for fabrics and food packaging have been detected in whole blood and serum of non-occupationally exposed humans in North America (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; Yeung et al., 2006). Sources of human exposure to PFCs have not been fully elucidated although diet has been suggested as the major route of exposure in two recent studies (Tittlemier et al., 2007; Trudel et al., 2008). Previous estimates of dietary exposure to PFCs range from approximately 1 ng kg body weight (bw) 1 d 1 (mean perfluorooc-

* Corresponding author. Tel.: +1 250 960 5237; fax: +1 250 960 5744. E-mail addresses: [email protected] (S.K. Ostertag), [email protected] (B.A. Tague), [email protected] (M.M. Humphries), Sheryl_tittlemier@hc-sc. gc.ca (S.A. Tittlemier), [email protected] (H.M. Chan). 0045-6535/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2009.02.053

tane sulfonate (PFOS) intake = 0.89 ng kg bw 1) for the population in Catalonia, Spain (Ericson et al., 2008) to 4 ng kg bw 1 d 1 for the general Canadian population (Tittlemier et al., 2007). Elevated exposure of PFCs has been associated with the consumption of fish in Polish individuals (Falandysz et al., 2006) and dietary exposure estimates from Spain found fish contributing largely to daily dietary exposure (Ericson et al., 2008). Furthermore, high intake of pilot whale meals by Faorese adolescents was associated with higher serum concentrations of PFOS, perfluorononanoate (PFNA) and perfluorododecanoate (PFDoA) compared to individuals eating little or no whale (Weihe et al., 2008); therefore, other northern populations may also be exposed to PFCs due to the consumption of marine mammals. The Inuit diet is composed of foods purchased from local markets (imported foods) and traditional foods obtained from locally harvested plants and wildlife (Kuhnlein et al., 2000). The consumption of traditional foods has been identified as a source of elevated exposure to mercury, PCBs and radionuclides for Canadian Inuit (Kuhnlein and Chan, 2000) and PFOS, PFCA and PFOS precursors (e.g. perfluorooctanesulfonamide derivatives) were recently detected in wildlife and fish species in the Canadian Arctic consumed

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by Inuit (Giesy and Kannan, 2001; Tomy et al., 2004; Martin et al., 2004a; Kannan et al., 2005; Smithwick et al., 2005a,b, 2006; Butt et al., 2007a,b). Dietary surveys conducted in the Canadian Arctic indicate that the traditional diet of Inuit is largely composed of caribou meat and marine mammal meat (Kuhnlein et al., 2000). However, most studies have measured PFCs in liver and blood samples from marine mammals, fish and birds in the Arctic for monitoring purposes (Giesy and Kannan, 2001; Tomy et al., 2004; Martin et al., 2004a; Kannan et al., 2005; Smithwick et al., 2005a,b, 2006; Butt et al., 2007a,b), therefore these data were unsuitable for the estimation of dietary exposure to PFCs among Inuit from the consumption of traditional foods. In this paper, we present the results of the analysis of PFCs and fluorotelomer unsaturated carboxylic acids (FTUCA) in archived traditional foods from Nunavut and estimate daily dietary exposure to these compounds for Inuit men and women in the late 1990s. Dietary exposure estimates were based on quantities of market and traditional foods consumed and concentrations of PFCs measured in traditional foods collected in Nunavut and previously analyzed composite samples of market and restaurant foods from Health Canada’s Total Diet Study (TDS) (Ostertag, 2008). Analyzing foods prepared as per consumption and from their packaging is important for estimating dietary exposure to PFCs; packaging was associated with the contamination of foods with PFOA (Begley et al., 2005) and PFC precursors (Tittlemier et al., 2006), and cooking fish reduced the concentration of PFCs by more than 50% (Del Gobbo et al., 2008). There are no human consumption guidelines for chronic exposure to PFOS and PFCA established by the World Health Organization or Health Canada. Therefore, a preliminary health risk assessment was carried out based on the provisional tolerable intake (pTDI) set by the German Drinking Water Commission (Drinking Water Commission, 2006) and toxicological endpoints from animal feeding studies (Thomford, 2002; Butenhoff et al., 2004). 2. Materials and methods 2.1. Standards, reagents and materials Eleven perfluorinated and fluorotelomer compounds (purity > 95%) were used as standards: perfluoroheptanoic acid (Aldrich, Oakville, ON, Canada), perfluoroctanoic acid (Wellington Laboratories, Guelph, ON, Canada), perfluorononanoic acid (Aldrich), perfluorodecanoic acid (Aldrich), perfluoroundecanoic acid (Aldrich), perfluorododecanoic acid (Aldrich), perfluorotetradecanoic acid (Aldrich), L-perfluorooctane sulfonate (Wellington), 2Hperfluoro-2-dodecenoic acid (Wellington), 2H-perfluoro-2-decenoic acid (Wellington) and 2H-perfluoro-2-octenoic acid (Wellington). Stable isotope-labelled perfluorinated and fluorotelomer compounds were used as recovery and internal performance standards: 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 perfluorononanoic acid (3 M, 95% chemical purity, 99% isotopic purity), 13C5 perfluorononanoic acid (Wellington), 1,2-13C perfluorodecanoic acid (Wellington Laboratories, 98% chemical purity, >99% isotopic purity), sodium 1,2,3,4-13C perfluorooctane sulfonate (Wellington, 98% chemical purity, >99% isotopic purity), L-18O2 PFOS (RTI International, Research Triangle Park, NC, USA), 2H-perfluoro-[1, 2-13C2]-2-octenoic acid (Wellington), 2H-perfluoro-[1,2-13C2]-2decenoic acid (Wellington) and 2H-perfluoro-[1,2-13C2]-2-dodecenoic acid (Wellington). All water used in the method was Milli-Q purified (Millipore, Billerica, MA, USA) and passed through a glass column containing Amberlite XAD-7 resin (Aldrich) to remove any possible perfluorinated contaminants. Methanol (MeOH; Optima, FisherScientific), ammonium hydroxide (Baker analyzed, 29% pur-

ity), glacial acetic acid (FisherScientific HPLC grade) and anhydrous sodium acetate were used without extra purification. Weak anion exchange (WAX) cartridges (OasisÒWax, 6 cc, 150 mg, 30 lm) solid-phase extraction (SPE) cartridges were purchased from Waters (Milford, MA). 2.2. Sample description Locally harvested animal and plant-derived foods samples were collected in Nunavut between 1997 and 1998 for the study ‘Assessment of Dietary Benefit/Risk in Inuit Communities’ (Kuhnlein et al., 2000). In total, 68 archived traditional food samples were analyzed and sample details are presented in Tables 1 and 2. All samples were stored in chemically cleaned polypropylene NalgeneTM containers and lids at 20 °C following homogenization. Food samples were selected for analysis to match the animal (species, tissue and preparation methods) cited in 24-h recalls conducted in Nunavut (Kuhnlein et al., 2000). Samples were primarily collected from Chesterfield Inlet, Igloolik, Pond Inlet and Qiqiktarjuaq in Nunavut. Frequently consumed foods and foods expected to contain greater concentrations of PFCs such as organ meats and blood, and tissue from animals at high trophic positions were analyzed. Another 65 samples from the Health Canada TDS collected in Whitehorse, YT, were analyzed previously and represent foods frequently consumed by Inuit (Kuhnlein et al., 2004), including coffee, tea, bread, potatoes and meat (chicken, pork, beef and processed meats). The results from the analysis of PFCs in the TDS samples are presented elsewhere (Ostertag, 2008). 2.3. Analytical method Identical methods were used for the extraction, clean-up and analysis of PFCs in traditional foods and TDS samples. Samples were thawed at room temperature and one gram of cooked or dried food, or 2 g raw food (liquid or solid) was placed in methanol-rinsed polypropylene centrifuge tubes. The difference in sample aliquot size was due to the poor yield of supernatant for 2 g of low moisture samples following methanol extraction (data not shown). The extraction of PFCA (C7–C11), PFOS and FTUCA was carried out with a methanol extraction modified from the method described by Tittlemier et al. (2005) followed by a solid-phase extraction described by Taniyasu et al. (2005). Each sample was spiked with 5000 pg recovery standard (50 lL of 100 pg lL 1 solution made up of 13C4 PFOA, 13C2 PFNA and 13C4 PFOS) and 4 mL methanol was added immediately to all samples except liquid samples. Liquid samples were freeze-dried for 6 h (Flexi-Dry MP microprocessor controlled bench top lyophilizer; FTS Systems, Inc., Stone Ridge, NY) prior to the addition of 4 mL methanol. The methanol extraction steps were as follows: tubes were capped, vortexed and placed on an orbital shaker at 200 rpm, 25 °C for 4 h, the samples were then vortexed and centrifuged at 667g, 10 °C for 10 min and the supernatants were transferred to precleaned polypropylene centrifuge tubes. Two more extractions were carried out under the following conditions: 2 mL methanol were added to the sample, vortexed and placed on the orbital shaker for 10 min and centrifuged (same conditions as above). Supernatants were combined, vortexed and dried to 0.5 mL under a gentle 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 methanol, 4 mL methanol and 4 mL water (2 drops per second) and samples were loaded and passed through the cartridge (1 drop per second), followed by 4 mL of 25 mM sodium acetate buffer (pH 4) to remove biomolecules and lipids and to improve adsorption of target compounds (Taniyasu et al., 2005). Elution was carried out with 4 mL methanol followed by 4 mL 0.1% NH4OH in metha-

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S.K. Ostertag et al. / Chemosphere 75 (2009) 1165–1172 Table 1 Concentration 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 Blood Meat

2 3 1 3 2 1 1 2 1 1 2 2 2 1 1 1 2 1 1 1 3 2 1 1

3.8, 7.6 2.9 ± 2.1 0.5 0.2 ± 0.3 0.1, <0.1 4.0 1.5 3.6, 1.6 0.4 0.2 <0.4 1.6, 0.4 0.5, 0.6 0.2 <0.1 0.2 <0.3 <0.2 1.6 0.3 <0.5, 0.4, 0.1 <0.2 <0.2

0.3, <0.2 0.1 ± 0.1 <0.5 <0.2 <0.2 <0.3 <0.2 <0.3 <0.3 <0.1 <0.3 <0.2 <0.6 <0.2 <0.1 <0.2 <0.3 <0.2 0.4 <0.2 <0.2, <0.1 <0.1 <0.4

1.9, 2.1 1.2 ± 0.3 0.5 0.9 ± 0.6 0.2, <0.2 0.8 0.4 0.6, 0.9 <0.4 <0.1 0.5, 0.5 <0.4 0.3, 1.2 <0.3 0.4 0.6 0.6, 0.8 <0.3 <0.1 <0.3 0.2 ± 0.3 <0.3 <0.3 0.5

0.5, <0.7 0.2 ± 0.2 <0.2 <0.3 0.1, <0.2 0.6 0.3 0.7, 0.8 <0.4 <0.2 <0.4 <0.2, 0.3 0.2, <0.4 <0.2 0.2 <0.2 0.2, <0.3 <0.2 0.6 0.3 0.1 ± 0.1 0.2, <0.2 0.1 <0.2

1.2, 0.6 0.6 ± 0.6 <0.2 <0.4 0.2, <0.1 1.6 0.7 2.0, 2.5 0.8 0.2 <0.4 <0.4, 0.3 0.2, 0.4 <0.2 <0.1 <0.3 <0.2 <0.2 0.3 0.1 <0.5, 0.1, 0.1 <0.2 <0.2

7.7, 10.2 5.0 ± 2.9 1.0 1.1 ± 0.5 0.6, nd 7.0 3.1 6.9, 5.8 1.2 0.4 0.5, 0.5 1.6, 1.0 1.2, 2.2 0.2 0.6 0.8 0.8, 0.8 nd 2.8 0.7 0.3 ± 0.4 0.7, 0.2 0.1 0.5

Polar Bear Beluga

Narwhal

Bearded Seal Walrus

Eider Duck Black Duck Arctic Char Lake Trout Seaweed Clams

Blubber Meat Blubber Meat Muktuk Blubber Muktuk Muktuk Intestine Meat Blubber Kauk Meat Whole Meat Whole Whole Whole Whole

Raw Raw Boiled Raw Raw Frozen Raw Dried Raw Raw Raw Frozen Boiled Boiled Aged Raw Raw Aged Boiled Boiled Raw Raw Raw Raw

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

Part and preparation

Caribou

Liver Meat

Bone marrow Heart, blood Fat Kidneys

Ptarmigan Arctic Hare Snow Goose Berries

Stomach Tongue Whole Meat Meat Whole

Baked Raw Boiled Dried Raw Roasted Boiled Raw Raw Raw Boiled Raw Raw Raw Raw Raw Raw

N

PFOS

PFOA

PFNA

PFDA

PFUA

Sum

1 3 2 2 2 1 1 1 1 2 1 1 3 3 2 1 3

5.0 2.7 ± 2.3 <0.3, 0.1 <0.4, <0.2 <0.2 0.2 0.2 <0.2 0.1, 0.1 <0.2 0.1 0.2 ± 0.2 <0.2 <0.2 <0.2 <0.1

0.7 0.1 ± 0.1 <0.1 <0.4 <0.3 <0.3 <0.2 <0.2 <0.2 <0.2 <0.2 0.8 0.0 ± 0.1 <0.2 <0.1 <0.1 <0.1

1.6 2.0 ± 1.7 0.8, <0.1 <0.9, 1.0 0.3, 0.3 1.0 0.6 0.8 <0.3 0.2, 0.2 <0.3 0.1 0.6 ± 0.6 <0.6 <0.3, 0.2 1.2 <0.3

0.6 0.7 ± 0.7 <0.2 <0.8 <0.2 0.4 0.2 0.2 <0.2 <0.2 <0.2 <0.2 <0.2 0.0 ± 0.1 <0.2, 0.2 <0.2 0.1 ± 0.1

1.1 0.7 ± 0.8 <0.5 <0.2 <0.2 <0.6 0.2 <0.3 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.1

9.0 6.2 ± 5.5 0.8, 0.1 nd, 1.0 0.3, 0.3 1.4 1.1 1.2 nd 0.3, 0.3 nd 1.0 0.8 ± 0.8 0.2 ± 0.02 0.0, 0.3 1.2 0.1 ± 0.1

nol (1 drop per second) and the eluate was dried to 0.5 mL under a gentle stream of nitrogen. The eluate was vortexed, a 250 lL aliquot was taken, 20 lL of the internal performance standard solution (concentration of 100 pg lL 1 for each of the following standards: 13C2 PFOA, 13C PFDA, 13C5PFNA, 13C FTUCA and L-18O2 PFOS) and 230 lL water were added. Samples were vortex-mixed and centrifuged at 2200 g for ten minutes and approximately 450 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 methods similar to those reported by Tittlemier et al. (2007). In brief, samples (10 lL injection) were chromatographed on a 2.1  50 mm Genesis C18 analytical column (Jones Chromatography Ltd., Hengoed, Mid Glamorgan, UK) and C18 guard column (4 mm  2.0 mm i.d.; Phenomenax, Torrance, CA) installed on an HP 1100 binary pump 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 chromatographically resolved using the following gradient program: 40% B at 0.200 mL min 1 for 1 min, 45% B over 4 min, increasing to 70% B over 8 min, 75% B over 2 min, and 95% B over 4 min and then held at 95% B for 0.1 min. The column was then flushed with 40% B for 10.9 min. The liquid chromatograph was connected to a VG Quattro II triple quadrupole mass spectrometer (Micromass, Manchester, UK). Analytes and the transitions monitored are provided in Table 3. Operational parameters for the mass spectrometer were as follows: capillary voltage 2.0 kV, source temperature 140 °C, and nebulizer and drying gas (N2) flow rates 20 L h 1 and 350 L h 1, respectively. The collision gas was nitrogen at 2.0  10 3 mbar and the mass resolution was set at 1.2 mass units at the base for both mass analyzers. 2.5. Quantitation and QA/QC Target analytes were considered to be positively identified if their retention time was within 2.5% of the standard retention

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

Performance standard

Mass transition

Cone voltage

Collision energy

Perfluoroheptanoate (PFHpA) Perfluorooctanoate (PFOA)

1,2-13C perfluorooctanoate 1,2-13C perfluorooctanoate

10 10

15 15

Perfluorononanoate (PFNA)

1,2,3,4,5-13C perfluorononanoate

Perfluorodecenoate (PFDA)

1,2-13C perfluorodecanoate

Perfluoroundecanoate (PFUA)

1,2-13C perfluorodecanoate

12 16 15 15 15

18 18 18 18 15

Perfluorooctane sulfonate (PFOS)

L-18O2 perfluorooctane sulfonate

50

60

6:2 Fluorotelomer unsaturated carboxylate (6:2 FTUCA) 8:2 Fluorotelomer unsaturated carboxylate (8:2 FTUCA) 10:2 Fluorotelomer unsaturated carboxylate (10:2 FTUCA)

2H-Perfluoro-[1,2-13C2]-2-octenoate 2H-Perfluoro-[1,2-13C2]-2-decenoate 2H-Perfluoro-[1,2-13C2]-2-dodecenoate

362.9 ? 318.8 412.9 ? 368.8 412.9 ? 168.8 462.8 ? 418.8 462.8 ? 218.8 512.8 ? 468.9 512.8 ? 218.9 562.9 ? 518.9 562.9 ? 268.8 498.9 ? 98.9 498.9 ? 79.9 356.9 ? 292.9 457 ? 392.9 557 ? 493

15 18 20

17 20 25

time, the signal-to-noise ratio was greater than three and the confirmation mass transition was present (when applicable). Relative response factors were calculated as a ratio of the peak area of the target analyte and corresponding stable isotope-labelled internal performance standard (presented in Table 3). Quantitation was based on an external five-point calibration curve made up in methanol and water (1:1 ratio) and the curve for each analyte consistently had an r2 value >0.98. Concentrations were not recoverycorrected. The IDL was estimated for each sample as the concentration for which the corresponding peak had a signal-to-noise ratio of 3. Method detection limits (MDL) were considered as three times the standard deviation of the blanks plus the IDL divided by the weight of sample (Smithwick et al., 2005a). If the blank was below the IDL, the MDL was estimated as three times the standard deviation of the lowest concentration standard of the calibration curve (Gomez-Taylor et al., 2003). The LOQ was determined as three times the MDL. QA/QC steps included methanol laboratory blanks and fortified matrix samples (homogenized raw ground beef fortified with 50 lL of a 100 pg lL 1 standard solution of target analytes) with each batch of samples (7–12 samples per batch) and the addition of stable isotope-labelled recovery internal standards and internal performance standards to each sample. 2.6. Dietary exposure estimate and statistical analyses Human ethics approval was obtained to carry out secondary data analysis with archived food samples and dietary intake information collected in Nunavut from the Ethics Review Board of McGill University. Dietary exposure to PFCs was estimated using concentration data from traditional foods measured in this study and data from the analysis of 65 composite samples from Health Canada’s 1998 Total Diet Study (TDS) measured previously (Ostertag, 2008). Concentration data for traditional food and TDS samples were matched with intake data from 24-h recalls conducted in Nunavut between 1997 and 1999 (Kuhnlein et al., 2000). Traditional foods analyzed were matched with intake data based on the species, part and preparation of foods consumed; TDS samples were matched based on the contents and preparation of foods consumed. PFC intake from individual foods was summed for each respondent to the 24-h recall; mean and 95th percentile of PFC exposure were then estimated for four age categories of men and women (13–19, 20–40, 41–60, older than 61 years old). Two dietary exposure estimates were calculated: a conservative estimate (
for age groups over 20 years old (64.2 kg for females and 71.6 kg for males) and the weights for American youth (Institute of Medicine, 2005) were used for Inuit youth (57 kg for females and 64 kg for males). A one-way ANOVA was carried out to identify whether age and gender were statistically significantly associated with PFC exposure. Pair-wise tests were run with adjustments for multiple comparisons using Bonferonni tests to compare mean exposure levels between age groups for each gender, and between genders in each age group. Maximum dietary exposure to PFCs was assessed by calculating the 95th percentiles for PFOS and combined PFCA/FTUCA intake for each age and gender group (adjusted for bw). All statistical analyses were carried out using SAS (Cary, NC v.9.1). Health risks posed by dietary exposure to PFCs among Inuit was assessed using the mean exposure and the 95th percentile of exposure based on the cautious exposure estimates (
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3.2. Concentrations in traditional foods The concentration of PFCs measured in the traditional food samples are presented in Tables 1 and 2. PFCs were detected in 61 of the 68 traditional food samples analyzed. Highest total PFC concentrations were detected in ringed seal liver, caribou liver, ringed seal blood, polar bear meat and beluga meat and total PFC concentrations were below 1 ng g 1 in 41 traditional foods analyzed. PFNA and PFOS were detected most frequently (44 and 39 samples, respectively) followed by PFDA (28 samples) and PFUA (23 samples). PFOA was rarely detected in traditional foods (only in nine samples). PFHpA and FTUCA were not detected in any sample analyzed. The sum of PFCA exceeded the concentration of PFOS in 51 of 68 traditional foods analyzed.

100 Exposure (ng/kg b.w./day)

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).

Total PFCA and FTUCA Exposure PFOS Exposure

90 80 70 60 50 40 30 20 10 0 <20

20-40

41-60

>60

95th percentile (
<20

20-40

41-60

>60

mean (
Age, Gender and Estimate Used Fig. 2. Estimated daily dietary exposure to PFOS and combined PFCA/FTUCA exposure among Inuit women. Mean and 95th percentiles of exposure are presented based on exposure estimates in which
3.3. Effects of preparation on PFC concentration An analysis of the effects of preparation on the concentration of PFCs was not possible due to the low sample size for traditional food samples that had undergone different preparation steps. Differences in PFC concentrations based on preparation were inconsistent in caribou and ringed seal meat, likely due to the small number of samples analyzed for the different preparations (boiled, dried, roasted and raw). The baked caribou liver sample (n = 1) had a 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 and traditional foods are presented in Figs. 1 and 2. Mean exposure ranged from 0.6 to 6.4 ng kg bw 1 d 1 for women (conservative approach,
3.5. Sources of exposure

100

Exposure (ng/kg b.w./day)

men in the 41–60 year age group had statistically significantly higher PFC exposure (p < 0.05) than younger men (<20 years old, 20–40 years old) and women from the same age group (conservative 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 approach). Mean daily exposure to combined PFCA/FTUCA ranged from 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 dietary 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. The contribution 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 composite samples of market foods from the Total Diet Study (data not shown). The hazard indices for dietary exposure to PFOS and combined PFCA/FTUCA were less than one for PFOS (0.03–0.04) and combined PFCA/FTUCA (0.49–0.78). The margin of exposure exceeded 1000 for PFOS and for PFCA/FTUCA (range: 7687–12 358) for all exposure estimates using the BMDL10 for PFOA (600 000 ng kg bw d 1) and LOEL (30 000 ng kg bw d 1).

Total PFCA and FTUCA Exposure PFOS Exposure

90 80 70 60 50 40 30 20 10 0 <20

20-40

41-60

>60

95th percentile (
<20

20-40

41-60

>60

mean (0.5* MDL)

Age, Gender and Estimate Used Fig. 1. Estimated daily dietary exposure to PFOS and combined PFCA/FTUCA exposure among Inuit men. Mean and 95th percentiles of exposure are presented based on exposure estimates in which
Traditional foods contributed a higher percentage to PFC dietary exposure than market foods as a dietary source of PFCs for Inuit in all age and gender groups (conservative approach,
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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 values below the MDL.

Mean Daily PFC Exposure (ng/day)

5000 4500 Traditional Foods Market Foods

4000 3500 3000 2500 2000 1500 1000 500 0 males

females

males


females
Age, Gender and Substitution Used (values < MDL) Fig. 4. A comparison of the mean contribution of market and traditional foods to dietary exposure to PFCs; values below MDL were substituted with zero or 0.5 * MDL.

traditional foods (i.e. ringed seal muscle and broth; beluga muktuk, blubber and caribou meat) or consumed one traditional food with a higher 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 in the meat of animals at higher trophic levels (i.e. polar bear, beluga) and in liver (i.e. caribou and ringed seal), which is consistent with observations that PFOS and PFOA biomagnify in aquatic food webs (Tomy et al., 2004; Martin et al., 2004a,b) and accumulate in liver and blood (Johnson et al., 1979; Vanden Heuvel et al., 1991). PFCs have been previously measured in ringed seal liver, beluga liver and clams from the Canadian Arctic (Tomy et al., 2004; Martin et al., 2004a). The concentrations of PFOS, PFNA and PFUA were similar 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) compared to levels previously measured (0.98–2.8 ng g 1, n = 19) (Martin et al., 2004a). PFOS was not detected in the one clam sample analyzed in our study, however, 0.28 ± 0.09 ng g 1 PFOS was measured in clams analyzed by Tomy et al. (2004). PFCs were detected in nearly every traditional food sample analyzed, which was in contrast to the results from the analysis of store-bought foods in Canada, Spain and the UK (Mortimer et al., 2006; Tittlemier et al., 2006, 2007; Ericson et al., 2008). Levels of PFCs in store-bought meats (Tittlemier et al., 2007) were similar to 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 caribou) and higher trophic level animal meat (e.g. polar bear, beluga) were higher than levels found in most store-bought foods in Canada (Tittlemier et al., 2007). 4.2. Dietary exposure estimates The conservative dietary exposure estimates from this study ranged from 0.2 to 2.4 ng kg bw 1 d 1 for PFOS, 0.1–0.5 ng 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 published exposure estimates. Dietary exposure estimates for PFOS were 1.07 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 from 1.1 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 (Fromme et al., 2007). PFNA exposure estimates were only available for the Canadian population (1.1 ng kg bw 1 d 1), given that PFNA was not detected in the duplicate diet study (Fromme et al., 2007) or market foods collected in Catalonia, Spain (Ericson et al., 2008). These results suggest that the consumption of locally harvested animals leads to a different PFCA exposure profile among Inuit in Nunavut compared to other populations. This may be due to the detection of PFNA at higher concentrations than PFOA in both aquatic and terrestrial Arctic species. In the study by Tittlemier et al. (2007), the concentration of PFNA exceeded that of PFOA in only one sample (beef steak: 4.4 ng g 1), and PFOA was detected more frequently than PFNA in the samples analyzed. PFNA may

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have been detected less frequently than PFOA in the study by Tittlemier 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 recalls may be used at the population level to address average intake for a large group of individuals (Beaton, 1992). Substituting zero for values below the MDL provided an underestimate of actual dietary exposure to PFCs for Inuit. However, given that only 8 of 65 market foods analyzed had detectable concentrations of PFCs, substituting half of the MDL for concentrations below the MDL likely led to an overestimate of exposure. The use of the cautious dietary exposure estimates in our risk assessment resulted in hazard indices for both PFOS and PFCA/FTUCA that were less than one, indicating that in a ‘‘worst-case-scenario”, the Inuit population in Nunavut would have lower levels of dietary exposure to PFCs than the pTDI. Comparing the estimated PFC exposure to toxicological endpoints indicated that the cautious exposure estimates (mean and 95th percentiles) were at least three orders of magnitude lower than doses associated with adverse outcomes in laboratory feeding trials. Therefore, dietary exposure to PFCs is of minimal health concern for the Inuit population, which is consistent with dietary exposure risk assessments for other populations (Fromme et al., 2007; Tittlemier et al., 2007; Ericson et al., 2008). The contamination of the Arctic with PFCs has resulted in dietary exposure of Inuit in Nunavut to PFCs at levels comparable to the Canadian and European populations. Although our data suggest that Inuit exposure to PFCs is lower than that considered as a concern for public health, our study does not fully address exposure to PFCA and PFOS precursors, which are expected to be present in both market and traditional foods (Tomy et al., 2004; Tittlemier et al., 2006; D’Eon and Mabury, 2007). The use of an internal dose of PFCs (i.e. concentration of PFCs in blood or serum) would reduce uncertainties associated with extrapolating animal exposure data to humans and would also take into account exposure to PFOS and PFCA precursors. Greater efforts to understand the sources of PFCAs and PFC precursors to the Arctic and to reduce these inputs are necessary to reduce Inuit exposure to PFCs. The PFC exposure estimates derived in this study do not indicate that dietary exposure to PFOS, PFCA or FTUCA poses any immediate health concern. Communication of health risk associated with PFC exposure should be undertaken in the context of recognizing the importance of traditional foods in Inuit culture and diet. Acknowledgements Funding for this work was provided by the Northern Contaminants Program, Health Canada, NSERC and ArcticNet. We thank Karen Pepper, Cathie Menard, and Donna Leggee for laboratory support and Rula Soueida for assistance with statistical analyses. References Beaton, G.H., 1992. Criteria of an Adequate Diet. Lea & Febiger, Philadelphia. Butenhoff, J.L., Gaylor, D.W., Moore, J.A., Olsen, G.W., Rodricks, J., Mandel, J.H., Zobel, L.R., 2004. Characterization of risk for general population exposure to perfluorooctanoate. Regul. Toxicol. Pharmacol. 39, 363–380. Begley, T.H., White, K., Honigfort, P., Twaroski, M.L., Neches, R., Walker, R.A., 2005. Perfluorochemicals: potential sources of and migratoin from food packaging. Food Addit. Contam. 22, 1023–1031. Butt, C.M., Mabury, S.A., Muir, D.C., Braune, B.M., 2007a. Prevalence of long-chained perfluorinated carboxylates in seabirds from the Canadian Arctic between 1975 and 2004. Environ. Sci. Technol. 41, 3521–3528. Butt, C.M., Muir, D.C., Stirling, I., Kwan, M., Mabury, S.A., 2007b. Rapid response of Arctic ringed seals to changes in perfluoroalkyl production. Environ. Sci. Technol. 41, 42–49.

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