Environ. Sci. Technol. 2007, 41, 2237-2242
Serum Concentrations of 11 Polyfluoroalkyl Compounds in the U.S. Population: Data from the National Health and Nutrition Examination Survey (NHANES) 1999-2000 ANTONIA M. CALAFAT,* ZSUZSANNA KUKLENYIK, JOHN A. REIDY, SAMUEL P. CAUDILL, JASON S. TULLY, AND LARRY L. NEEDHAM Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia 30341
We measured the concentrations of 11 polyfluoroalkyl compounds (PFCs), including perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid (PFHxS) in 1562 serum samples collected from a representative U.S. population 12 years of age and older in the 1999-2000 National Health and Nutrition Examination Survey. Participants represented both sexes, three race/ethnicities (non-Hispanic blacks, non-Hispanic whites, and Mexican-Americans), and four age categories (12-19 years, 20-39 years, 40-59 years, and 60 years and older). PFCs were extracted from 100 µL of serum using on-line solid-phase extraction coupled to isotope dilutionhigh performance liquid chromatography-tandem mass spectrometry; limits of detection ranged from 0.05 to 0.2 ng/ mL. PFOS, PFOA, PFHxS, and perfluorooctane sulfonamide were detected in all samples analyzed; 2-(N-ethylperfluorooctane sulfonamido) acetic acid, 2-(N-methylperfluorooctane sulfonamido) acetic acid, and perfluorononanoic acid were detected in more than 90% of samples, which suggests prevalent exposures to several PFCs in the U.S. population. The concentrations of most PFCs were similar regardless of the participants’ ages but were higher in males than in females. Mexican Americans had lower concentrations than non-Hispanic blacks and nonHispanic whites, whose concentrations were similar. Higher education was associated with higher concentrations of PFOS and PFOA. These data will serve as a nationally representative baseline of the U.S. population’s exposure to PFCs to which other populations can be compared, and will play an important role in public health by helping set research priorities, ranging from health effects studies to defining sources and pathways of exposure.
Introduction Polyfluoroalkyl compounds (PFCs) have been used extensively in commercial applications including surfactants, * Corresponding author phone: (770) 488-7891; fax: (770) 4884371; e-mail:
[email protected]. 10.1021/es062686m Not subject to U.S. Copyright. Publ. 2007 Am. Chem. Soc. Published on Web 03/06/2007
lubricants, paper and textile coatings, polishes, food packaging, and fire-retarding foams. Some PFCs, including perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), are persistent in humans and the environment, and they have been found worldwide in wildlife (1, and references therein) and in the general population (2-7). Results of animal studies suggest potential adverse health effects including genotoxicity, reproductive and developmental toxicity, and carcinogenicity associated with exposures to PFOS and PFOA (8-10). By contrast, in a few occupational studies (11-13) and in one population exposed to PFOA through contaminated drinking water (14), no clear association has been established between exposure and adverse health effects. The National Health and Nutrition Examination Survey (NHANES), conducted annually since 1999 by the Centers for Disease Control and Prevention (CDC), is designed to measure the health and nutritional status of the civilian noninstitutionalized U.S. population 2 months of age and older (15). The surveys include household interviews, collection of medical histories, standardized physical examinations, and collection of biological specimens. Some of these specimens can be used to assess exposure to environmental chemicals (16). Previously, we used 54 pooled serum samples collected from participants of the 2001-2002 NHANES to obtain estimates of mean concentrations of 11 PFCs in selected demographic groups (17). We now report the results of the analyses of 1562 individual serum samples collected from 1999-2000 NHANES participants. These data provide the first estimation of concentrations of these same 11 PFCs in a representative sample of the non-institutionalized U.S. population 12 years of age and older.
Materials and Methods Survey Design. NHANES 1999-2000 was a complex, multistage probability survey conducted in 26 locations throughout the United States that included examinations of 9282 people. Informed written consent was obtained from all participants (18). Serum samples analyzed for PFCs were obtained by venipuncture from 1562 people, a random onethird subsample of participants 12 years of age and older. Because the subsample was a random selection from the entire set, the representational aspect of the survey was maintained. Laboratory Methods. Serum specimens were shipped on dry ice and stored at -70 °C. Using online solid-phase extraction coupled to high performance liquid chromatography-tandem mass spectrometry, described in detail elsewhere (19), we measured in 100 µL of serum 11 analytes, including PFOS, PFOA, perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), perfluorooctane sulfonamide (PFOSA), 2-(N-ethyl-perfluorooctane sulfonamido) acetic acid (Et-PFOSA-AcOH), and 2-(N-methyl-perfluorooctane sulfonamido) acetic acid (Me-PFOSA-AcOH) (Table S1). For quantification, we used 18O2-PFOS and 18O2-PFOSA (RTI International, Research Triangle Park, NC), and 13C2PFOA provided by Dupont Co. (Wilmington, DE). Low- and high-concentration quality control materials, prepared from a calf serum pool, were analyzed with the unknown samples to ensure data accuracy and reliability (19). Statistical Analysis. Statistical analyses were performed using SAS (version 9.1) and SUDAAN (release 8.0 2001). SUDAAN calculates variance estimates after incorporating the sample population weights, which were designed for the one-third subset used and accounted for the unequal selection probabilities caused by the cluster design and VOL. 41, NO. 7, 2007 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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TABLE 1. Geometric Mean and Selected Percentiles of Perfluorooctane Sulfonic Acid (PFOS) Concentrations in Serum (in ng/mL) for the U.S. Population 12 Years of Age and Older: Data from NHANES 1999-2000a geometric mean 10th total
N (%)b
selected percentiles 25th
50th
75th
90th
95th
30.4 (27.1-33.9) 15.1 (13.0-17.4) 21.9 (19.2-23.9) 30.2 (27.8-33.8) 43.5 (37.5-47.3) 57 (50.2-71.7)
75.6 (58.1-97.5) 1562
Age Group (Years) 12-19 20-39 40-59 60+
29.1 (26.2-32.4) 27.5 (24.9-30.2) 33.0 (28.0-38.8) 33.3 (28.5-38.8)
16.3 (12.0-18.4) 14.4 (11.9-17.6) 16.5 (14.3-17.9) 15.0 (13.5-19.2)
22.4 (18.5-25.3) 20.3 (18.8-22.3) 23.0 (18.7-27.8) 23.6 (20.0-26.5)
29.4 (26.8-34.2) 27.9 (24.8-29.7) 33.6 (28.0-38.7) 33.7 (27.4-39.9)
38.9 (35.9-45.0) 37.3 (33.9-42.3) 46.6 (37.9-57.0) 46.1 (41.1-56.3)
52.7 (45.6-56.2) 50.2 (45.5-55.9) 75.2 (47.1-98.4) 67.0 (54.0-101)
57.4 (52.7-66.5) 56.8 (51.4-71.7) 94.3 (58.0-131) 95.6 (58.1-119)
543 364 295 360
males 33.4 (29.6-37.6) 17.9 (14.3-20.2) 24.8 (21.1-28.4) 34.8 (31.1-37.9) 46.1 (41.0-50.2) 58.3 (50.2-78.3) 78.3 (58.0-108) females 28.0 (24.6-31.8) 13.8 (11.4-16.6) 19.4 (17.3-22.3) 27.7 (24.5-30.2) 38.8 (32.7-46.0) 55.4 (46.3-70.2) 75.7 (56.1-98.4)
743 819
Sex
Race/Ethnicityc MA NHB NHW
22.7 (19.8-25.9) 11.9 (10.6-12.8) 16.0 (13.7-18.7) 23.7 (20.8-27.2) 32.9 (27.8-39.6) 41.7 (36.5-53.6) 53.6 (41.3-72.0) 33.0 (26.2-41.6) 14.9 (11.6-21.0) 21.9 (14.9-31.7) 32.0 (24.3-45.7) 50.6 (37.4-62.2) 68.8 (62.0-75.9) 82.8 (68.7-114) 32.0 (29.1-35.2) 16.8 (14.4-18.9) 23.7 (21.7-25.7) 32.4 (29.3-35.5) 44.8 (39.7-47.6) 56.2 (50.4-67.8) 75.7 (58.0-98.4)
a The 95% confidence intervals are shown in parentheses. (non-Hispanic blacks), NHW (non-Hispanic whites).
b
584 309 529
N (sample size). PFOS was detected in all samples. c MA (Mexican-Americans), NHB
TABLE 2. Geometric Mean and Selected Percentiles of Perfluorooctanoic Acid (PFOA) Concentrations in Serum (in ng/mL) for the U.S. Population 12 Years of Age and Older: Data from NHANES 1999-2000a geometric mean
total
N (%)b
selected percentiles 10th
25th
50th
75th
90th
95th
2.8 (2.5-3.0)
3.8 (3.4-4.3)
5.1 (4.7-5.7)
6.8 (6.3-7.7)
9.4 (8.2-11.0)
11.9 (10.9-13.5)
1562
5.5 (5.0-6.0) 5.2 (4.7-5.7) 5.4 (4.7-6.2) 4.8 (4.3-5.5)
3.2 (2.9-3.8) 2.6 (2.3-3.0) 2.8 (2.4-3.4) 2.6 (1.8-3.0)
4.3 (3.9-4.6) 3.8 (3.2-4.5) 3.8 (3.4-4.4) 3.4 (3.2-3.9)
5.6 (4.8-6.1) 5.2 (4.7-6.2) 5.2 (4.5-5.9) 4.8 (4.3-5.1)
6.9 (6.2-7.5) 7.1 (6.4-7.8) 6.9 (6.0-8.7) 6.4 (5.7-7.5)
9.4 (7.7-11.0) 9.3 (7.8-11.0) 9.4 (7.7-14.1) 8.8 (7.3-12.0)
11.2 (10.2-12.5) 10.9 (8.4-14.0) 13.0 (10.0-17.7) 11.5 (8.7-17.1)
543 364 295 360
5.7 (5.2-6.3) 4.8 (4.3-5.3)
3.1 (2.8-3.5) 2.6 (2.3-2.8)
4.3 (3.8-4.9) 3.4 (3.0-3.9)
6.0 (5.4-6.4) 4.6 (4.2-5.0)
7.6 (6.8-8.4) 6.2 (5.6-7.0)
10.5 (9.0-11.8) 8.3 (7.5-9.9)
12.1 (11.0-13.1) 11.3 (9.2-14.4)
743 819
1.9 (1.6-2.2) 2.5 (2.2-2.9) 3.2 (2.9-3.5)
2.8 (2.3-3.4) 3.3 (2.7-4.1) 4.1 (3.5-4.6)
4.2 (3.7-4.6) 4.8 (4.0-5.9) 5.5 (4.9-6.2)
5.8 (5.2-6.2) 6.5 (5.9-7.5) 7.3 (6.5-8.2)
7.6 (6.4-8.0) 8.8 (7.4-11.5) 10.0 (8.3-12.0)
8.0 (7.7-8.9) 11.1 (9.2-14.0) 12.9 (11.0-14.9)
584 309 529
5.2 (4.7-5.7)
Age Group (Years) 12-19 20-39 40-59 60+
Sex males females
Race/Ethnicityc MA NHB NHW
3.9 (3.6-4.2) 4.8 (4.1-5.6) 5.6 (5.0-6.2)
a The 95% confidence intervals are shown in parentheses. (non-Hispanic blacks), NHW (non-Hispanic whites).
b
N (sample size). PFOA was detected in all samples. c MA (Mexican-Americans), NHB
planned oversampling of certain subgroups. Geometric means, calculated only for analytes detected in g60% of the samples, and percentiles for the PFCs concentrations (in ng/ mL) were obtained using SUDAAN. For concentrations below the limit of detection (
