Table of Contents

Component Description

Urinary Polycyclic aromatic Hydrocarbons (PAHs)

PAHs constitute a group of chemicals which are formed during the incomplete combustion of coal, oil and gas, garbage, and other organic substances. In general, people are exposed to mixtures of PAHs, and the sources are widespread, including vehicle exhausts, asphalt, coal tar, wild fires, agricultural burning, charbroiled foods, and tobacco smoke. PAHs enter the body quickly and easily by all routes of exposure and are readily and predominantly metabolized to hydroxylated metabolites and glucuronide metabolites. These compounds require metabolic activation in order to interact with cellular macromolecules. Measurement of urinary metabolites indicates exposure to the parent PAHs. Although background ranges of PAHs in air and water are known, less is known about PAH background levels in humans.

Eligible Sample

Participants aged 20 years and older who met the regular one-third subsample selection criteria were included in the adult special subsample.  Additionally, to augment the adult special subsample, those survey participants aged 20 years and older, not in the regular one-third subsample, who smoked at least 100 cigarettes in their entire lifetime (SMQ020=1) and now smoke cigarettes every day (SMQ040=1), were also eligible as an oversampling of smokers.

Description of Laboratory Methodology

The specific analytes measured in this method are monohydroxylated metabolites of PAHs (OH-PAHs). This procedure involves enzymatic hydrolysis of glucuronidated/sulfated OH-PAH metabolites in urine, extraction, derivatization, and analysis using isotope dilution capillary gas chromatog¬raphy tandem mass spectrometry (GC-MS/MS). Ion transitions specific to each analyte and carbon-13 labeled internal standards are monitored, and the abundances of each ion are measured.

Data Processing and Editing

The analytical methods are described in the Description of Laboratory Methodology section above.

Laboratory Quality Assurance and Monitoring

Urine 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 instructions on specimen collection and processing 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 laboratories. NCEH developed and distributed a quality control protocol for all the laboratories which outlined the Westgard rules used when running NHANES specimens. Summary statistics for each control pool, QC graphs, and any special considerations are submitted to NCHS. NCHS reviewed the data for trends or shifts. 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

Refer to the 2011-2012 Laboratory Data Overview for general information on NHANES laboratory data.

Special weights

Urinary PAHs were measured in a one third subsample of persons 6 years and older. 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  laboratory data must be conducted with the key survey design and basic demographic variables. The NHANES 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 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 URD___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 URX___ provides the analytic result for that analyte. For analytes with analytic results below the lower limit of detection (i.e., URD___LC=1), an imputed fill value was placed in the analyte results field. This value is the lower limit of detection divided by square root of 2 (LLOD/sqrt(2)).

The lower limit of detection (LLOD, in ng/L) for urinary PAHs:

Analyte Item ID LLOD
Urinary 2-Hydroxyfluorene URXP04 10
Urinary 3-Hydroxyfluorene URXP03 10
Urinary 9-Hydroxyfluorene URXP17 10
Urinary 1-Hydroxyphenanthrene URXP06 10
Urinary 2-Hydroxyphenanthrene URXP07 10
Urinary 3-Hydroxyphenanthrene URXP05 10
Urinary 1-Hydroxypyrene URXP10 10
Urinary 1-Hydroxynapthalene (1-Naphthol) URXP01 44
Urinary 2-Hydroxynapthalene (2-Naphthol) URXP02 42
Urinary 4-Hydroxyphenanthrene URXP19 10

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.

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 20 YEARS - 150 YEARS

WTFSM - Two year smoking weights

Variable Name:
WTFSM
SAS Label:
Two year smoking weights
English Text:
Two year smoking weights
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 700606.64741 Range of Values 2349 2349
. Missing 0 2349

URXP01 - 1-hydroxynaphthalene (ng/L)

Variable Name:
URXP01
SAS Label:
1-hydroxynaphthalene (ng/L)
English Text:
1-hydroxynaphthalene (ng/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
49 to 16658076 Range of Values 2259 2259
. Missing 90 2349

URDP01LC - 1-hydroxynaphthalene comment code

Variable Name:
URDP01LC
SAS Label:
1-hydroxynaphthalene comment code
English Text:
1-hydroxynaphthalene comment code
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2259 2259
1 Below lower detection limit 0 2259
. Missing 90 2349

URXP02 - 2-hydroxynaphthalene (ng/L)

Variable Name:
URXP02
SAS Label:
2-hydroxynaphthalene (ng/L)
English Text:
2-hydroxynaphthalene (ng/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
144 to 181354 Range of Values 2259 2259
. Missing 90 2349

URDP02LC - 2-hydroxynaphthalene comment code

Variable Name:
URDP02LC
SAS Label:
2-hydroxynaphthalene comment code
English Text:
2-hydroxynaphthalene comment code
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2259 2259
1 below lower detection limit 0 2259
. Missing 90 2349

URXP03 - 3-hydroxyfluorene (ng/L)

Variable Name:
URXP03
SAS Label:
3-hydroxyfluorene (ng/L)
English Text:
3-hydroxyfluorene (ng/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7.1 to 11600 Range of Values 2255 2255
. Missing 94 2349

URDP03LC - 3-hydroxyfluorene comment code

Variable Name:
URDP03LC
SAS Label:
3-hydroxyfluorene comment code
English Text:
3-hydroxyfluorene comment code
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2215 2215
1 Below lower detection limit 40 2255
. Missing 94 2349

URXP04 - 2-hydroxyfluorene (ng/L)

Variable Name:
URXP04
SAS Label:
2-hydroxyfluorene (ng/L)
English Text:
2-hydroxyfluorene (ng/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
11 to 75607 Range of Values 2259 2259
. Missing 90 2349

URDP04LC - 2-hydroxyfluorene comment code

Variable Name:
URDP04LC
SAS Label:
2-hydroxyfluorene comment code
English Text:
2-hydroxyfluorene comment code
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2259 2259
1 Below lower detection limit 0 2259
. Missing 90 2349

URXP05 - 3-hydroxyphenanthrene (ng/L)

Variable Name:
URXP05
SAS Label:
3-hydroxyphenanthrene (ng/L)
English Text:
3-hydroxyphenanthrene (ng/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7.1 to 16822 Range of Values 2258 2258
. Missing 91 2349

URDP05LC - 3-hydroxyphenanthrene comment code

Variable Name:
URDP05LC
SAS Label:
3-hydroxyphenanthrene comment code
English Text:
3-hydroxyphenanthrene comment code
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2198 2198
1 Below lower detection limit 60 2258
. Missing 91 2349

URXP06 - 1-hydroxyphenanthrene (ng/L)

Variable Name:
URXP06
SAS Label:
1-hydroxyphenanthrene (ng/L)
English Text:
1-hydroxyphenanthrene (ng/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7.1 to 7475 Range of Values 2259 2259
. Missing 90 2349

URDP06LC - 1-hydroxyphenanthrene comment code

Variable Name:
URDP06LC
SAS Label:
1-hydroxyphenanthrene comment code
English Text:
1-hydroxyphenanthrene comment code
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2257 2257
1 Below lower detection limit 2 2259
. Missing 90 2349

URXP07 - 2-hydroxyphenanthrene (ng/L)

Variable Name:
URXP07
SAS Label:
2-hydroxyphenanthrene (ng/L)
English Text:
2-hydroxyphenanthrene (ng/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7.1 to 12420 Range of Values 2255 2255
. Missing 94 2349

URDP07LC - 2-hydroxyphenanthrene comment code

Variable Name:
URDP07LC
SAS Label:
2-hydroxyphenanthrene comment code
English Text:
2-hydroxyphenanthrene comment code
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2226 2226
1 Below lower detection limit 29 2255
. Missing 94 2349

URXP10 - 1-hydroxypyrene (ng/L)

Variable Name:
URXP10
SAS Label:
1-hydroxypyrene (ng/L)
English Text:
1-hydroxypyrene (ng/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7.1 to 12349 Range of Values 2256 2256
. Missing 93 2349

URDP10LC - 1-hydroxypyrene comment code

Variable Name:
URDP10LC
SAS Label:
1-hydroxypyrene comment code
English Text:
1-hydroxypyrene comment code
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2229 2229
1 Below lower detection limit 27 2256
. Missing 93 2349

URXP17 - 9-hydroxyfluorene (ng/L)

Variable Name:
URXP17
SAS Label:
9-hydroxyfluorene (ng/L)
English Text:
9-hydroxyfluorene (ng/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
12 to 79645 Range of Values 2259 2259
. Missing 90 2349

URDP17LC - 9-hydroxyfluorene comment code

Variable Name:
URDP17LC
SAS Label:
9-hydroxyfluorene comment code
English Text:
9-hydroxyfluorene comment code
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2259 2259
1 Below lower detection limit 0 2259
. Missing 90 2349

URXP19 - 4-phenanthrene (ng/L)

Variable Name:
URXP19
SAS Label:
4-phenanthrene (ng/L)
English Text:
4-phenanthrene (ng/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7.1 to 1643 Range of Values 2244 2244
. Missing 105 2349

URDP19LC - 4-phenanthrene comment code

Variable Name:
URDP19LC
SAS Label:
4-phenanthrene comment code
English Text:
4-phenanthrene comment code
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 1806 1806
1 Below lower detection limit 438 2244
. Missing 105 2349

URXUCR - Urinary creatinine

Variable Name:
URXUCR
SAS Label:
Urinary creatinine
English Text:
Urinary creatinine
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
4 to 800 Range of Values 2293 2293
. Missing 56 2349