Table of Contents

Component Description

Organic fluorochemicals are used in multiple commercial applications including surfactants, lubricants, paints, polishes, food packaging and fire-retarding foams. Several of these polyfluorochemicals (PFCs) are ubiquitous contaminants found both in humans and animals worldwide. Perfluorooctane sulfonate (PFOS) has been used in a wide variety of industrial and consumer products including protective coatings for carpets and apparel, paper coatings, insecticide formulations, and surfactants. In May 2000, the 3M Company, the sole manufacturer of PFOS in the United States and the principal manufacturer worldwide, announced that it was discontinuing the production of perfluorooctanyl fluoride-based chemistries, including PFOS. Perfluorooctanoic acid (PFOA) is used primarily to produce its salts which are used in the production of fluoroelastomers and fluoropolymers, such as polytetrafluoroethylene (PTFE) and polyvinylidine fluoride (PVDF). PTFE has numerous uses in many industrial and consumer products, including coatings on textiles and carpet; uses in the automotive, mechanical, aerospace, chemical, electrical, medical, and building/construction industries; personal care products; and non-stick coatings on cookware. PVDF is used primarily in electrical/electronics, building/construction, and chemical processing industrial sectors.

Eligible Sample

Participants aged 12 years and older who met the subsample requirements.

Description of Laboratory Methodology

The test principle utilizes solid phase extraction-high performance liquid chromatography-turboionspray ionization-tandem mass spectrometry (SPE-HPLC-TCI-MS/MS) for the quantitative detection of PFCs: perfluorooctane sulfonamide (PFOSA), 2-(N-methyl-perfluorooctane sulfonamido) acetic acid (Me-PFOSA-AcOH), 2-(N-ethyl-perfluorooctane sulfonamido) acetic acid (Et-PFOSA-AcOH), perfluorohexane sulfonate (PFHxS), PFOS, perfluoropentanoate (PFPeA), perfluorohexanoate (PFHxA), perfluoroheptanoate (PFHpA), PFOA, perfluorononanoate (PFNA), perfluorodecanoate (PFDeA), perfluoroundecanoate (PFUA), and perfluorododecanoate (PFDoA) (16). The PFCs are extracted from serum using an automated SPE procedure, separated from other extracted components in the SPE eluate by reversed phase HPLC, and detected by negative ion TIS-MS/MS using a multiple reaction monitoring experiment. This method allows for rapid detection of these fluorochemicals in human serum with limits of detection in the low parts per billion (ppb or ng/mL) range.

Laboratory Quality Assurance and Monitoring

Serum specimens are processed, stored, and shipped to the Division of Environmental Health Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention for analysis.

Detailed specimen collection and processing instructions are discussed in the NHANES Laboratory/Medical Technologists Procedures Manual (LPM). Vials are stored under appropriate frozen (–20°C) conditions until they are shipped to National Center for Environmental Health for testing.

Mobile Examination Centers (MECs)

Laboratory team performance is monitored using several techniques. NCHS and contract consultants use a structured quality assurance evaluation during unscheduled visits to evaluate both the quality of the laboratory work and the quality-control procedures. Each laboratory staff person is observed for equipment operation, specimen collection and preparation; testing procedures and constructive feedback are given to each staff. Formal retraining sessions are conducted annually to ensure that required skill levels were maintained.

The NHANES QA/QC protocols meet the 1988 Clinical Laboratory Improvement Amendments mandates. Detailed QA/QC instructions are discussed in the NHANES LPM.

Analytical Laboratories

NHANES uses several methods to monitor the quality of the analyses performed by the contract laboratories. In the MEC, these methods include performing blind split samples collected on “dry run” sessions. In addition, contract laboratories randomly perform repeat testing on 2.0% of all specimens.

NCHS developed and distributed a quality control protocol for all the contract laboratories which outlined the Westgard rules used when running NHANES specimens. Progress reports containing any problems encountered during shipping or receipt of specimens, summary statistics for each control pool, QC graphs, instrument calibration, reagents, and any special considerations are submitted to NCHS and Westat quarterly. The reports are reviewed for trends or shifts in the data. The laboratories are required to explain any identified areas of concern.

All QC procedures recommended by the manufacturers were followed. Reported results for all assays meet the Division of Laboratory Science’s quality control and quality assurance performance criteria for accuracy and precision (similar to specifications outlined by Westgard (1981).

Analytic Notes

Subsample weights

Measures of serum polyfluorinated chemicals were measured in a one third subsample of persons 12 years and over. Special 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.

Variance estimation

The analysis of NHANES 2003-2004 laboratory data must be conducted with the key survey design and basic demographic variables. The NHANES 2003-2004 Demographic Data File contains demographic and 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.

Links to NHANES Data Files

This laboratory data file can be linked to the other NHANES 2003-2004 data files using the unique survey participant identifier SEQN.

Detection Limits

The detection limits were constant for all of the analytes in the data set. Two variables are provided for each of these analytes. The variable named LBD___LC indicates whether the result was below the limit of detection. There are two values: “0” and “1”. “0” means that the result was at or above the limit of detection. “1” indicates that the result was below the limit of detection.

The other variable named LBX___ provides the analytic result for that analyte.

The constant lower limits of detection for each polyfluorochemical is:

Constant Lower Limits of Detection for Polyfluorochemicals
Analyte  Item ID LLOD 
 Perfluorooctanoic acid  LBXPFOA  0.1
 Perfluorooctane sulfonic acid  LBXPFOS  0.4
 Perfluorohexane sulfonic acid  LBXPFHS  0.3
 2-(N-Ethyl-perfluorooctane sulfonamido) acetic acid  LBXEPAH  0.4
 2-(N-Methyl-perfluorooctane sulfonamido) acetic acid  LBXMPAH  0.52
 Pefluorodecanoic acid  LBXPFDE  0.3
 Perfluorobutane sulfonic acid  LBXPFBS  0.4
 Perfluoroheptanoic acid  LBXPFHP  0.3
 Perfluorononanoic acid  LBXPFNA  0.1
 Perfluorooctane sulfonamide  LBXPFSA  0.2
 Perfluoroundecanoic acid  LBXPFUA  0.3
 Perflurododecanoic acid  LBXPFDO  1

Please refer to the Analytic Guidelines for further details on the use of sample weights and other analytic issues.

References

Codebook and Frequencies

SEQN - Respondent sequence number

Variable Name:
SEQN
SAS Label:
Respondent sequence number
English Text:
Respondent sequence number.
Target:
Both males and females 12 YEARS - 150 YEARS

WTSA2YR - Two-year MEC weights of subsample A

Variable Name:
WTSA2YR
SAS Label:
Two-year MEC weights of subsample A
English Text:
Two-year MEC weights of subsample A
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 455771.88304 Range of Values 2368 2368
. Missing 0 2368

LBXPFOA - Perfluorooctanoic acid

Variable Name:
LBXPFOA
SAS Label:
Perfluorooctanoic acid
English Text:
Perfluorooctanoic acid
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.1 to 77.2 Range of Values 2094 2094
. Missing 274 2368

LBDPFOAL - Perfluorooctanoic acid comment

Variable Name:
LBDPFOAL
SAS Label:
Perfluorooctanoic acid comment
English Text:
Perfluorooctanoic acid comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2085 2085
1 Below lower detection limit 9 2094
. Missing 274 2368

LBXPFOS - Perfluorooctane sulfonic acid

Variable Name:
LBXPFOS
SAS Label:
Perfluorooctane sulfonic acid
English Text:
Perfluorooctane sulfonic acid
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.3 to 435 Range of Values 2094 2094
. Missing 274 2368

LBDPFOSL - Perfluorooctane sulfonic acid comment

Variable Name:
LBDPFOSL
SAS Label:
Perfluorooctane sulfonic acid comment
English Text:
Perfluorooctane sulfonic acid comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2091 2091
1 Below lower detection limit 3 2094
. Missing 274 2368

LBXPFHS - Perfluorohexane sulfonic acid

Variable Name:
LBXPFHS
SAS Label:
Perfluorohexane sulfonic acid
English Text:
Perfluorohexane sulfonic acid
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.2 to 82 Range of Values 2094 2094
. Missing 274 2368

LBDPFHSL - Perfluorohexane sulfonic acid comment

Variable Name:
LBDPFHSL
SAS Label:
Perfluorohexane sulfonic acid comment
English Text:
Perfluorohexane sulfonic acid comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2046 2046
1 Below lower detection limit 48 2094
. Missing 274 2368

LBXEPAH - 2-(N-ethyl-PFOSA) acetate

Variable Name:
LBXEPAH
SAS Label:
2-(N-ethyl-PFOSA) acetate
English Text:
2-(N-Ethyl-perfluorooctane sulfonamido) acetic acid
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.1 to 4.1 Range of Values 2094 2094
. Missing 274 2368

LBDEPAHL - 2-(N-ethyl-PFOSA) acetate comment

Variable Name:
LBDEPAHL
SAS Label:
2-(N-ethyl-PFOSA) acetate comment
English Text:
2-(N-Ethyl-perfluorooctane sulfonamido) acetic acid comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 79 79
1 Below lower detection limit 2015 2094
. Missing 274 2368

LBXMPAH - 2-(N-methyl-PFOSA) acetate

Variable Name:
LBXMPAH
SAS Label:
2-(N-methyl-PFOSA) acetate
English Text:
2-(N-Methyl-perfluorooctane sulfonamido) acetic acid
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.37 to 54.3 Range of Values 2094 2094
. Missing 274 2368

LBDMPAHL - 2-(N-methyl-PFOSA) acetate comment

Variable Name:
LBDMPAHL
SAS Label:
2-(N-methyl-PFOSA) acetate comment
English Text:
2-(N-Methyl-perfluorooctane sulfonamido) acetic acid comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 504 504
1 Below lower detection limit 1590 2094
. Missing 274 2368

LBXPFDE - Perfluorodecanoic acid

Variable Name:
LBXPFDE
SAS Label:
Perfluorodecanoic acid
English Text:
Pefluorodecanoic acid
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.1 to 3.7 Range of Values 2094 2094
. Missing 274 2368

LBDPFDEL - Perfluorodecanoic acid comment

Variable Name:
LBDPFDEL
SAS Label:
Perfluorodecanoic acid comment
English Text:
Pefluorodecanoic acid comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 579 579
1 Below lower detection limit 1515 2094
. Missing 274 2368

LBXPFBS - Perfluorobutane sulfonic acid

Variable Name:
LBXPFBS
SAS Label:
Perfluorobutane sulfonic acid
English Text:
Perfluorobutane sulfonic acid
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.1 to 1.2 Range of Values 2094 2094
. Missing 274 2368

LBDPFBSL - Perfluorobutane sulfonic acid comment

Variable Name:
LBDPFBSL
SAS Label:
Perfluorobutane sulfonic acid comment
English Text:
Perfluorobutane sulfonic acid comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 6 6
1 Below lower detection limit 2088 2094
. Missing 274 2368

LBXPFHP - Perfluoroheptanoic acid

Variable Name:
LBXPFHP
SAS Label:
Perfluoroheptanoic acid
English Text:
Perfluoroheptanoic acid
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.2 to 3.8 Range of Values 2094 2094
. Missing 274 2368

LBDPFHPL - Perfluoroheptanoic acid comment

Variable Name:
LBDPFHPL
SAS Label:
Perfluoroheptanoic acid comment
English Text:
Perfluoroheptanoic acid comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 160 160
1 Below lower detection limit 1934 2094
. Missing 274 2368

LBXPFNA - Perfluorononanoic acid

Variable Name:
LBXPFNA
SAS Label:
Perfluorononanoic acid
English Text:
Perfluorononanoic acid
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.1 to 11.5 Range of Values 2094 2094
. Missing 274 2368

LBDPFNAL - Perfluorononanoic acid comment

Variable Name:
LBDPFNAL
SAS Label:
Perfluorononanoic acid comment
English Text:
Perfluorononanoic acid comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2058 2058
1 Below lower detection limit 36 2094
. Missing 274 2368

LBXPFSA - Perfluorooctane sulfonamide

Variable Name:
LBXPFSA
SAS Label:
Perfluorooctane sulfonamide
English Text:
Perfluorooctane sulfonamide
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.1 to 3.1 Range of Values 2094 2094
. Missing 274 2368

LBDPFSAL - Perfluorooctane sulfonamide comment

Variable Name:
LBDPFSAL
SAS Label:
Perfluorooctane sulfonamide comment
English Text:
Perfluorooctane sulfonamide comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 443 443
1 Below lower detection limit 1651 2094
. Missing 274 2368

LBXPFUA - Perfluoroundecanoic acid

Variable Name:
LBXPFUA
SAS Label:
Perfluoroundecanoic acid
English Text:
Perfluoroundecanoic acid
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.1 to 6.9 Range of Values 2094 2094
. Missing 274 2368

LBDPFUAL - Perfluoroundecanoic acid comment

Variable Name:
LBDPFUAL
SAS Label:
Perfluoroundecanoic acid comment
English Text:
Perfluoroundecanoic acid comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 174 174
1 Below lower detection limit 1920 2094
. Missing 274 2368

LBXPFDO - Perfluorododecanoic acid

Variable Name:
LBXPFDO
SAS Label:
Perfluorododecanoic acid
English Text:
Perfluorododecanoic acid
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.1 to 1 Range of Values 2094 2094
. Missing 274 2368

LBDPFDOL - Perfluorododecanoic acid comment

Variable Name:
LBDPFDOL
SAS Label:
Perfluorododecanoic acid comment
English Text:
Perflurododecanoic acid comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 1 1
1 Below lower detection limit 2093 2094
. Missing 274 2368