• Component Description
• Eligible Sample
• Description of Laboratory Methodology
• Laboratory Quality Assurance and Monitoring
• Data Processing and Editing
• Analytic Notes
• References
• Codebook
  • SEQN - Respondent sequence number
  • WTSSBH2Y - Surplus specimen B 13-14 2 year weights
  • SSCLPF - 9-chlorohexadecafluoro3oxanonane (ng/mL)
  • SSCLPFL - 9-chlorohexadecafluoro(ng/mL) Comt code
  • SSDONA - Adona(8dioxa3Hperfluorononanoate)(ng/mL)
  • SSDONAL - Adona(perfluorononanoate) Comt code
  • SSGENX - GenX(HFPO-DA propanoateammonium(ng/mL)
  • SSGENXL - GenX(HFPO-DA propanoateammonium Cmt code
  • SSPFBA - Perflurobutanoic acid (ng/mL)
  • SSPFBAL - Perflurobutanoic acid (ng/mL) Comt code
  • SSFPEA - Perfluoropentanoic acid (ng/mL)
  • SSFPEAL - Perfluoropentanoic acid (ng/mL)Comt code
  • SSPFHA - Perfluorohexanoic acid (ng/mL)
  • SSPFHAL - Perfluorohexanoic acid (ng/mL) Comt code
  • SSPFHP - Perfluoroheptanoic acid (ng/mL)
  • SSPFHPL - Perfluoroheptanoic acid (ng/mL)Comt code
  • SSNFOA - Linear perfluorooctanoate (ng/mL)
  • SSNFOAL - Linear perfluorooctanoate Comt code
  • SSBFOA - Branch isomers-perfluorooctanoate(ng/mL)
  • SSBFOAL - Br. isomers-perfluorooctanoate Comt code
  • SSPFNA - Perfluorononanoic acid (ng/mL)
  • SSPFNAL - Perfluorononanoic acid (ng/mL) Comt code
  • SSPFDE - Pefluorodecanoic acid (ng/mL)
  • SSPFDEL - Pefluorodecanoic acid (ng/mL) Comt code
  • SSPFUA - Perfluoroundecanoic acid (ng/mL)
  • SSPFUAL - Perfluoroundecanoic acid(ng/mL)Comt code
  • SSPFBS - Perfluorobutane sulfonic acid (ng/mL)
  • SSPFBSL - Perfluorobutane sulfonic acid Comt code
  • SSPFHS - Perfluorohexane sulfonic acid (ng/mL)
  • SSPFHSL - Perfluorohexane sulfonic acid Comt code
  • SSFHPS - Perfluoroheptane sulfonic acid (ng/mL)
  • SSFHPSL - Perfluoroheptane sulfonic acid Comt code
  • SSNFOS - Linear perfluorooctane sulfonate(ng/mL)
  • SSNFOSL - Lin perfluorooctane sulfonate Comt code
  • SSMFOS - Monomethyl branch isomers-PFOS (ng/mL)
  • SSMFOSL - Monomethyl branched isomers-PFOS Cmt cd

National Health and Nutrition Examination Survey

2013-2014 Data Documentation, Codebook, and Frequencies

Perfluoroalkyl and Polyfluoroalkyl Substances (SSPFSU_H)

Data File: SSPFSU_H.xpt

First Published: April 2019

Last Revised: April 2022

Component Description

Exposure data to per-and polyfluoroalkyl substances (PFAS) among the U.S. general population have been included in the National Health and Nutrition Examination Survey (NHANES) since 1999-2000 (CDC 2018). Several long-chain PFAS, including perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), have been frequently detected at trace levels in the blood of NHANES participants, while short-chain PFAS (e.g., perfluorobutane sulfonic acid, perfluoroheptanoic acid) have not (CDC 2018). The lower detection frequencies and concentration ranges may reflect lower exposure to short-chain PFAS than to PFOS or PFOA or that, in humans, short-chain PFAS efficiently eliminate in urine. However, PFAS have not been measured in the urine of NHANES participants.

Because of changes in the manufacturing and environmental emissions of long-alkyl chain PFAS since the early 2000s, PFAS with shorter alkyl chains, and fluorinated alternatives, including perfluoroalkyl ether carboxylic acids (PFECAs) and perfluoroalkyl ether sulfonic acids have entered the market (Gordon 2011, Wang et al. 2013), and the environment (Xiao 2017). Two PFECAs, GenX (ammonium salt of 2,3,3,3,-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-propanoate]) and ADONA (ammonium salt of 4,8-dioxa-3H-perfluorononanoate [DONA]), have shorter elimination half-lives in animals than PFOA (Gannon et al. 2016). The detection of GenX in surface waters and drinking water (Heydebreck et al. 2015, Sun et al. 2016) has raised concerns about potential health implications from human exposure to PFECAs through contaminated drinking water. Exposure data to alternative PFAS in the U.S. general population do not exit.

To fill these exposure data gaps, we measured seventeen PFAS, including three fluorinated alternatives used as PFOA or PFOS replacements, in one-third subsample of participants 6+ years of age using surplus urine collected for the measurement of select personal care product chemicals as part of NHANES 2013-2014.

Eligible Sample

One-third subsample of participants aged 6+ years from NHANES 2013-2014 with stored urine (N=2682).

Description of Laboratory Methodology

We used solid phase extraction coupled to high performance liquid chromatography-tandem mass spectrometry for the quantitative detection of 17 PFAS: perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), linear perfluorooctanoic acid (n-PFOA), branched isomers of PFOA (Sb-PFOA), perfluorononanoic acid (PFNA), pefluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorobutane sulfonic acid (PFBS), perfluorohexane sulfonic acid (PFHxS), perfluoroheptane sulfonic acid (PFHpS), linear perfluorooctane sulfonic acid (n-PFOS), monomethyl branched isomers of PFOS (Sm-PFOS), 2,3,3,3,-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-propanoate (HFPO-DA or GenX), dodecafluoro-3H-4,8-dioxanoate (DONA), and 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate (9Cl-PF3ONS). Briefly, after incubation with β-glucuronidase followed by dilution with formic acid, 50 μL of urine is injected into a commercial column switching system allowing for concentration and chromatographic separation of the analytes. Detection and quantification are done using tandem mass spectrometry as described in detail (Kato, et al. 2018).

To estimate the total (sum of the isomers measured) concentrations of PFOS and PFOA for each participant, sum the concentrations of n-PFOA and Sb-PFOA for PFOA, and those of n-PFOS and Sm-PFOS for PFOS. If the value of one isomer is less than the limit of detection (LOD), then the imputed value is used. The imputed value is calculated as the LOD divided by the square root of 2 (Hornung et al. 1990) and imputed values are provided in the NHANES public release file. If the values of all isomers are reported as less than the LOD, then the sum will be the sum of each imputed value.

Laboratory Quality Assurance and Monitoring

The analytical measurements were conducted following strict quality control/quality assurance CLIA guidelines. Along with the study samples, each analytical run included high- and low-concentration quality control materials (QCs) and serum blanks to assure the accuracy and reliability of the data. The concentrations of the high-concentration QCs and the low-concentration QCs, averaged to obtain one measurement of high-concentration QC and low-concentration QC for each run, were evaluated using standard statistical probability rules (Caudill et al. 2008).

Data Processing and Editing

Data were received after all analyses were complete. The data were not edited.

Data Access: All data are publicly available.

Analytic Notes

Refer to the 2013-2014 Laboratory Data Overview for general information on NHANES laboratory data.

Demographic and Other Related Variables

The analysis of NHANES laboratory data must be conducted with the key survey design and basic demographic variables. The NHANES 2013-2014 Demographic Data File contains demographic data, health indicators, and other related information collected during household interviews as well as the sample design variables. The recommended procedure for variance estimation requires use of stratum and PSU variables (SDMVSTRA and SDMVPSU, respectively) in the demographic data file.

This laboratory data file can be linked to other NHANES data files using the unique survey participant identifier (i.e., SEQN).

Detection Limits

Detection limits were constant for all of the analytes in the data set. Two variables are provided for each analyte.

The variable name ending in “L” (e.g., SSPFNAL) indicates whether the result was below the limit of detection: the value “0” means that the result was at or above the limit of detection, “1” indicates that the result was below the limit of detection. For analytes with results below the lower limit of detection (e.g., SSPFNAL=1), an imputed fill value was placed in the results field. This value is the lower limit of detection divided by square root of 2 (LLOD/sqrt2).

The other variable prefixed SS (e.g., SSPFNA) provides the analytic result for each analyte.

The lower limit of detection (LLOD, in ng/mL) for the seventeen PFAS are:

Variable Name	SAS Label	LLOD
SSCLPF	9-chlorohexadecafluoro-3-oxanonane-1-sulfonate (ng/mL)	0.10
SSDONA	Adona (ammonium salt of 4,8-dioxa-3H-perfluorononanoate)  (ng/mL)	0.10
SSGENX	GenX (HFPO-DA or ammonium salt of 2,3,3,3,-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-propanoateammonium salt of 2,3,3,3,-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-propanoate) (ng/mL)	0.10
SSPFBA	Perflurobutanoic acid (ng/mL)	0.10
SSFPEA	Perfluoropentanoic acid (ng/mL)	0.10
SSPFHA	Perfluorohexanoic acid (ng/mL)	0.10
SSPFHP	Perfluoroheptanoic acid (ng/mL)	0.10
SSNFOA	Linear perfluorooctanoate (ng/mL)	0.10
SSBFOA	Branched isomers of perfluorooctanoate (ng/mL)	0.10
SSPFNA	Perfluorononanoic acid (ng/mL)	0.10
SSPFDE	Pefluorodecanoic acid (ng/mL)	0.10
SSPFUA	Perfluoroundecanoic acid (ng/mL)	0.10
SSPFBS	Perfluorobutane sulfonic acid (ng/mL)	0.10
SSPFHS	Perfluorohexane sulfonic acid (ng/mL)	0.10
SSFHPS	Perfluoroheptane sulfonic acid (ng/mL)	0.10
SSNFOS	Linear perfluorooctane sulfonate (PFOS) (ng/mL)	0.10
SSMFOS	Monomethyl branched isomers of PFOS (ng/mL)	0.10

Subsample Weights

Sample weights are required to analyze these data properly. Specific sample weights for this subsample are included in this data file and should be used when analyzing these data. Previous versions of this data file included a sample weight variable (WTSB2YR) but when observations were removed from this data file, a new sample weight was created, and a new sample weight variable was added to this data file (WTSSBH2Y). Please refer to the NHANES Analytic Guidelines and the on-line NHANES Tutorial for further details on the use of sample weights and other analytic issues.

References

• Caudill SP, Schleicher RL, Pirkle JL. 2008. Multi-rule quality control for the age-related eye disease study. Statist Med 27:4094-4106.

• CDC. 2018. Fourth National Report on Human Exposure to Environmental Chemicals, Updated Tables, March 2018. In https://www.cdc.gov/exposurereport/pdf/FourthReport_UpdatedTables_Volume1_Mar2018.pdf Atlanta, GA:Centers for Disease Control and Prevention; National Center for Environmental Health; Division of Laboratory Sciences.

• Gannon SA, Fasano WJ, Mawn MP, Nabb DL, Buck RC, Buxton LW, Jepson GW, and Frame SR. 2016. Absorption, distribution, metabolism, excretion, and kinetics of 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoic acid ammonium salt following a single dose in rat, mouse, and cynomolgus monkey. Toxicology 340:1-9.

• Gordon SC. 2011. Toxicological evaluation of ammonium 4,8-dioxa-3H-perfluorononanoate, a new emulsifier to replace ammonium perfluorooctanoate in fluoropolymer manufacturing. Regulatory Toxicology and Pharmacology 59:64-80.

• Heydebreck F, Tang J, Xie Z, and Ebinghaus R. 2015. Alternative and Legacy Perfluoroalkyl Substances: Differences between European and Chinese River/Estuary Systems. Environmental Science and Technology 49:8386-8395.

• Hornung, R.W., Reed, L.D., 1990. Estimation of average concentration in the presence of nondetectable values. Appl. Occup. Environ. Hyg. 5, 46–51.

• Kato K, Kalathil AA, Patel AM, Ye X, Calafat AM. 2018. Per- and polyfluoroalkyl substances and fluorinated alternatives in urine and serum by on-line solid phase extraction-liquid chromatography-tandem mass spectrometry. Chemosphere 209:338-345.

• Sun M, Arevalo E, Strynar M, Lindstrom A, Richardson M, Kearns B, Pickett A, Smith C, and Knappe DRU. 2016. Legacy and Emerging Perfluoroalkyl Substances Are Important Drinking Water Contaminants in the Cape Fear River Watershed of North Carolina Environ. Sci. Technol. Lett. 3:415-419.

• Wang ZY, Cousins IT, Scheringer M, and Hungerbuhler K. 2013. Fluorinated alternatives to long-chain perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkane sulfonic acids (PFSAs) and their potential precursors. Env. Int. 60:242-248.

• Xiao F. 2017. Emerging poly- and perfluoroalkyl substances in the aquatic environment: A review of current literature. Water Res 124:482-495.

Codebook and Frequencies