Environ. Sci. Technol. 2009, 43, 5130–5136
Determinants of Plasma Concentrations of Perfluorooctanesulfonate and Brominated Organic Compounds in Nunavik Inuit Adults (Canada) ´ E DALLAIRE,† PIERRE AYOTTE,† RENE ´ RY,‡ DARIA PEREG,† SERGE DE PIERRE DUMAS,§ E ´ RIC LANGLOIS,§ AND E ´ R I C D E W A I L L Y * ,† Public Health Research Unit, Centre hospitalier universitaire de Que´bec-CHUL, Que´bec, Que´bec, Canada, Nunavik Regional Board of Health and Social Services, Kuujjuaq, Que´bec, Canada, and Centre de toxicologie du Que´bec, Institut national de sante´ publique du Que´bec, Que´bec City, Que´bec, Canada
Received January 16, 2009. Revised manuscript received May 4, 2009. Accepted May 5, 2009.
Perfluorooctanesulfonate (PFOS) and brominated organic compounds (BOCs) have been found in biota and humans worldwide with levels of BOCs being the highest in North America. PFOS and BOC exposure of remote populations that consume species of a marine food web for their subsistence has seldom been investigated. In 2004, we determined the concentrations of these contaminants in 883 Nunavik Inuit adults from the Canadian Arctic and investigated the demographic and dietary factors associated with them. Demographic and dietary information were collected by questionnaires. Multiple linear regressions were conducted to investigate predictors of exposure to those contaminants. Polychlorinated biphenyl (PCB) congener 153 concentrations are presented for comparative purposes. PFOS and PCB 153 were detected in all samples, with plasma concentrations several times higher than BOCs. The consumption of fish and marine mammals appears to be an important contributor to PFOS exposure among Nunavik Inuit. While PBDE 153 also appears as a persistent PBDE congener, exposure to PBDE 47 seems to be more recent in this population. Adoption of a westernized lifestyle seems to be related to an increased exposure to PBDE 47, but specific sources remain to be elucidated. In conclusion, we found that the remote geographical location and traditional lifestyle of the Nunavik Inuit population do not protect them against exposure to emerging POPs, particularly PFOS.
Introduction Perfluorooctanesulfonate (PFOS) is a chemical belonging to the large group of perfluorinated compounds (PFCs) char* Corresponding author phone: (418)656-4141, ext. 46518; fax: (418)654-2726; e-mail:
[email protected]. Corresponding author address: Unite´ de recherche en Sante´ Publique, Centre Hospitalier Universitaire de Que´bec-CHUL, 2875 Boulevard Laurier, ´ difice Delta 2, bureau 600, Que´bec, G1V 2M2, Canada. E † Centre hospitalier universitaire de Que´bec-CHUL. ‡ Nunavik regional board of health and social services. § Institut national de sante´ publique du Que´bec. 5130
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acterized by a very stable fully fluorinated carbon chain with hydrophobic properties. This product is incorporated into a variety of commercial products such as surfactants, lubricants, food packaging, and grease repellents in textiles and carpets among others. Moreover, PFOS was shown to be a degradation product of several other PFCs (1). Biomonitoring of PFCs in the environment, wildlife, and humans indicates that PFOS is highly prevalent and seems to persist and biomagnify along marine and terrestrial food chains (2, 3). Animal studies have shown that PFOS may alter thyroid hormone homeostasis and affect fatty acid transport and metabolism as well as membrane function (4, 5). In general human populations, health effects assessments of PFOS exposure are limited and focus mainly on growth effects of developmental exposure (6, 7). Brominated organic compounds (BOCs) is an extensive group of chemicals that includes naturally occurring brominated compounds and synthetic substances such as brominated flame retardants, the largest market group of bromine derivatives. The latter family comprises numerous substances including polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), and tetrabromobisphenol A (TBBPA). With the exception of PBBs and some PBDE mixtures, these compounds are still used in various industrial and commercial products such as textiles and electronic devices (8). PBDEs have been detected worldwide in humans and biota with levels substantially higher in North America (9, 10). Because they share some physical and chemical properties with PCBs, PBDEs may induce similar detrimental developmental, hormonal, and reproductive effects (11). Biotransformation of PBDEs by liver enzymes leads to the formation of hydroxylated metabolites (HOPBDEs). Several HO-PBDEs were recently measured in children from Nicaragua, and for some of them levels were similar or higher than those of parent compounds (12). Bromophenols were detected in mice after exposure to the commercial DE-71 formulation and therefore constitutes another group of PBDE metabolites (13). Bromophenols are also known to occur naturally in the marine environment (14). HO-PBDEs and bromophenols were shown to possess a high affinity for the thyroid transport protein transthyretin (15), whereas the latter have also been associated with the disruption of calcium signaling (16). Human exposure to legacy persistent pollutants such as PCBs and other organochlorine compounds is a well-known phenomenon in the Canadian Arctic. Nunavik Inuit are exposed to a plethora of toxic substances that are carried from southern to northern latitudes by oceanic and atmospheric transport as their traditional diet comprises large amounts of tissues from fish and marine mammals contaminated by persistent organic pollutants (POPs). More recently, the presence of PFOS and PBDEs was reported in several wildlife species of the Arctic (17, 18). However, exposure to these emerging POPs has not been investigated in the Inuit population. Therefore, the aim of this study was to quantify plasma levels of PFOS, some BOCs, and their metabolites in Nunavik Inuit adults and to determine demographic characteristics and dietary habits of participants associated with those concentrations. PCB 153 concentrations were used for comparison purposes.
Materials and Methods Study Design and Data Collection. A large scale health survey was conducted among the Inuit population of Nunavik from August 27 to October 1 2004. Nunavik is the northern region of Que´bec where approximately 9500 Inuit live in 14 10.1021/es9001604 CCC: $40.75
2009 American Chemical Society
Published on Web 06/01/2009
TABLE 1. Characteristics of the 883 Inuit Participants, Nunavik, Que´ bec, Canada characteristics gender men women age (years) BMI (kg/m2) fish intake (g/day)a marine mammal intake (g/day)a n-3 PUFAs (% total fatty acids) land animal meats (g/day)a fruit and vegetables (g/day) dairy intake (g/day) market meat intake (g/day) smoking status nonsmoker ex-smoker smoker alcohol consumption daily occasionally never education no yes income (Canadian $/annually) 60000
percentage 45.4 54.6
mean ( SDb
range
38 ( 15 27.4 ( 5.7 49.0 ( 71.7 27.6 ( 49.7 9.7 ( 3.5 139.9 ( 268.3 674.9 ( 671.5 182.7 ( 431.6 166.1 ( 132.6
18-89 17.2-48.0 0-641.1 0-410.4 1.7-20.5 0-4356.0 0-4809.8 0-7097.8 0-1067.0
1.6 15.2 83.2 24.1 49.4 26.6 8.5 91.5 53.7 42.4 3.9
a Consumption of fish and marine mammals are expressed in g/day on an annual basis. deviation.
communities along the coasts of Hudson Bay and Ungava Bay. The target population of this study was permanent Inuit residents of Nunavik aged 18 years old and older. In order to obtain a standard representation of the target population, the survey used a two-stage stratified random sampling. The first stage was a proportional random sample of private Inuit households. In the second stage, all members of the family living in the household were asked to participate. The communities were the only stratification variable. Several self-administered and interviewer-completed questionnaires were used to obtained information regarding demographics, lifestyle habits, and nutrition. In addition, individuals were asked to participate in a clinical session where blood samples were taken and physical measurements were performed. Overall, the participation rate for the different collection instruments was approximately 50%, for a total of 1056 participants. Concerning blood sampling, a total of 883 samples were available for chemical analyses. The survey was approved by the Comite´ d’e´thique de la recherche de l’Universite´ Laval and the Comite´ d’e´thique de sante´ publique du Que´bec. All participants gave informed consent before taking part in the study. Food Frequency Questionnaire. Data on food intakes were obtained using a food frequency questionnaire that was administered to 778 participants for a participation rate of 67%. The questionnaire documented their daily consumption of traditional food (i.e., derived from fishing and hunting) for all four seasons during the year preceding the survey. Additionally, consumption frequency of store bought food items (fruit, vegetables, meats [beef, veal, pork, lamb, and poultries], and dairy products) during the month preceding the survey was collected with the food frequency questionnaire. Laboratory Procedures. Blood samples (60 mL) were collected using a venous catheter from an antecubital vein. Tubes were centrifuged within 3 h of collection, and plasma was isolated, aliquoted, and frozen at -80 °C prior to clinical biochemistry and contaminant analyses. Plasma samples
b
Abbreviation: SD, standard
were analyzed for PCBs and BOCs, including brominated phenolics, according to the multiresidue method previously described (10, 19). Plasma PFOS determination was performed by electrospray LC-MS-MS analysis. Information regarding the analytical procedures for these contaminants can be found in the Supporting Information. Limits of detection (LOD) for PCB 153 and BOCs are presented in Table 2. The LOD for PFOS was 100 ng/L. Concentrations of PBDEs and PCB 153 in plasma were also expressed as micrograms per kilogram of lipids (Table S1). Cholesterol and triglyceride analyses were performed using a Hitachi 917 auto analyzer and reagents from Roche Diagnostics. Concentrations of total plasma lipids were estimated according to the formula developed by Phillips et al. (20). Erythrocyte fatty acid profiles were obtained by gas-liquid chromatography (HP 5890; Hewlett-Packard, Canada) using an Innowax capillary column (30 m × 0.25 mm × 0.25 µm; Agilent, Canada) (21). Chromatographies were calibrated using a mixture of 37 different fatty acids (FAME 37; Supelco, PA). n-3 PUFAs were expressed as the percentage of total erythrocyte membrane fatty acids. Statistical Analysis. Statistical analyses were conducted with SAS (version 9.1; SAS Institute Inc., Cary, NC, USA) and SUDAAN software (version 9.0.1, Research Triangle Institute, Research Triangle Park, NC). Plasma concentrations of contaminants and food consumption frequency follow a lognormal distribution and were transformed accordingly. A value equal to half the limit of detection of the analytical method was attributed to nondetected contaminants in biological samples. The sum of PBDE includes congeners 47, 99, 100, and 153. Intercorrelations between contaminants were evaluated with the Spearman correlation coefficient for contaminants with a detection frequency of at least 75%, excepted for PBDE 47. This compound was included regardless of detection frequency because of the growing concern regarding the rapid increase in concentrations measured in human samples in North America and because of its VOL. 43, NO. 13, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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TABLE 2. Plasma Concentrations of PFOS and BOCs in Inuit Participants from Nunavik, Que´ bec, Canadab wet weight concentrations (ng/L) analytes
N
PFOS PCB 153 BOCs PBDE 47 PBDE 99 PBDE 100 PBDE 153 PBB 153 2′-HO-BDE 68 2′-HO-BDE 75 tetrabromobisphenol A 2,4-DBP 2,6-DBP 2,4,6-TBP 2,3,4,5-TeBP 2,3,4,6-TeBP 2,3,5,6-TeBP PBP
857 883 838 832 838 838 838 771 771 771 112 143 143 722 722 143 722
LOD
percent detected
100 10
100 100
15 10 10 5 5 5 2.5 10 50 5 5 1 1 5 1
GM
95% CI
range
17750-19660 1076-1275
480-470000 42-41000
35
33-38
17
16-18
