Table of Contents

Component Description

The Family Smoking Prevention and Tobacco Control Act of 2009 gave the Food and Drug Administration regulatory authority over tobacco products. In Section 907(a), the Act states that the Secretary of Health and Human Services shall establish tobacco product standards. These product standards shall also include provisions for the testing of the tobacco products. In order to determine the effectiveness of these product standards, it is critical that surveillance systems be in place before the standards are enacted to determine whether they impact exposure of people who continue to use tobacco product. NHANES is an ideal source of human samples for assessing smokers in multiple locations around the country. NHANES will provide the most robust dataset possible for identifying changes in exposure of smokers that should result from enactment of tobacco product standards.

We anticipate that the results of this survey of tobacco exposure biomarkers will be used by FDA, other government agencies, and research institutions. The NHANES data will be used to determine the effectiveness of initial product standards and direct whether further changes to product standards need to be made.

Exposure to volatile organic compounds (VOCs) is ubiquitous. Chronic exposure to high levels of some VOCs can lead to cancer and neurocognitive dysfunction. Nearly 200 VOCs have been associated with adverse health effects in occupational studies or laboratory studies, but have not been monitored in general population groups. Metabolites of some VOCs can be detected in urine following exposure events. Therefore, information on exposure to these compounds, as measured by their metabolite concentrations in urine, is essential to understand the levels of hazardous VOCs to which the general population is exposed.

Eligible Sample

Urine collected from participants in NHANES 2005-2006 aged 12 years and older from a one-half subsample were eligible. Tests were conducted on residual urine samples.

Description of Laboratory Methodology

This method is a quantitative procedure for the measurement of VOC metabolites in human urine using ultra performance liquid chromatography coupled with electro spray tandem mass spectrometry (UPLC-ESI-MS/MS) (Alwis et al., 2012). Chromatographic separation is achieved using an Acquity UPLC® HSS T3 (Part no. 186003540, 1.8 mm x 2.1 mm x 150 mm, Waters, Inc.) column with 15 mM ammonium acetate and acetonitrile as the mobile phases. The eluent from the column is ionized using an electrospray interface to generate and transmit negative ions into the mass spectrometer. Comparison of relative response factors (ratio of native analyte to stable isotope labeled internal standard) with known standard concentrations yields individual analyte concentrations.

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 reagent 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

The data were reviewed. Incomplete data or improbable values were sent to the performing laboratory for confirmation.

Analytic Notes

Special Analytic Note: Bias Adjustments Applied to VOC Metabolites in Urine Assay in NHANES 2005–2006 cycle (Surplus)

Adjustments have been applied to the previously published data.

During routine review, several systematic biases were discovered in measurements of certain urinary VOC metabolites in the 2005 – 2006 and 2011 – 2012 NHANES cycles. The systematic nature of these biases permitted retrospective adjustment through a statistical approach based on linear regression modeling where adjusted measurements are predicted from unadjusted measurements using suitable data. The “statistical recalibrations” implemented here have the general form of a univariate linear regression equation (accounting for dilution factors routinely used during measurement):

 

 

where exp[·] and ln(·) are the natural exponential and natural logarithm functions, respectively. Natural log-transformation of both the un-adjusted and adjusted measurements moderated adverse influence on model fit from extreme measurements. The estimated regression slope and intercept are m and b, respectively, which are tabulated below for each analyte. The dilution factor was accounted for only once for each analyte that underwent more than one statistical recalibration (e.g., URXMB3). Statistical recalibration for the mass fraction of salt (URXHP2, URXGAM) only required a regression slope (i.e., ).

The explanatory power of the linear regressions was excellent (), and residuals exhibited distributions with good approximation to normality, as well as stable variance over the observed range of measurements. These favorable diagnostics demonstrate the efficacy of statistical recalibration for the retrospective amelioration of systematic bias.

Correction for Change in Internal Standard

Isotopically labeled internal standards were not commercially available for URXMB3 and URXHP2 during analysis of NHANES 2005–2006. Instead, the lab used surrogate internal standards.  Isotopically labeled internal standards later became available for purchase and were used in the NHANES 2011–2012 cycle. A systematic bias between these two cycles was noted and confirmed to be due to the internal standard change.

Analyte Code

m used in correction

b used in correction

URXMB3

1.08034

0.73526

URXHP2

0.99437

0.21216

Correction for Variation in Preparation of Neat Native Metabolites Standards

During the 2005–2006 and 2011–2012 NHANES cycles, calibrators were prepared from a multi-analyte stock solution formulated from neat materials in-house. Beginning with the NHANES 2015–2016 cycle, calibrators and the multi-analyte stock solution were prepared externally. A systematic bias between the cycles that used in-house calibration materials and the cycle using externally prepared calibration materials was observed for analytes listed in the table below. Further validation of the externally prepared calibrators suggested that the in-house calibrators were inaccurate due to special requirements for handling and preparing accurate solutions from neat materials, some of which are highly hygroscopic.

Analyte Code

m used in correction

b used in correction

URXAMC

0.99687

0.12843

URXCEM

1.01462

-0.13642

URXDHB

0.99654

0.04687

URXHEM

1.00947

0.30195

URXHPM

0.98949

-0.23802

URXMAD

1.00736

-0.18993

URXTTC

1.03057

-0.07460

URXMB3

0.97491

-0.43202

URX2DC

1.00155

-0.32374

Correction for Mass Fraction of Salt in Neat Compound Standard

During the 2005–2006 and 2011–2012 NHANES cycles, calibrators were prepared from a multi-analyte stock solutions formulated from neat materials in-house. Beginning with the NHANES 2015–2016 cycle, calibrators and the multi-analyte stock solutions were prepared externally. A systematic bias between the cycles that used in-house calibration materials and the cycle using externally prepared calibration materials was observed for analytes listed in the table below. Further validation confirmed that the large mass fraction of salt in the neat materials was not accounted for during formulation of in-house calibration materials. This discrepancy between the calculated concentration of the calibrators and the actual concentration led to a systematic bias in results for URXHP2 and URXGAM.

Analyte Code

m used in correction

URXHP2

0.54711990

URXGAM

0.57755045

Correction for Stereoisomerism in Urine Samples

URXMB3 occurs in human urine predominantly in the cis isomer, but quantitation in the NHANES 2005–2006 and NHANES 2011–2012 cycles used standards containing the trans isomer. This discrepancy led to a systematic bias in the URXMB3 results. Neat material that is purely cis isomer cannot be readily obtained, but a predictive regression equation can account for these quantitative differences.

Analyte Code

m used in correction

b used in correction

URXMB3

0.97741

-0.18775

 

Detection Limits

 
The detection limits were constant for the analytes in the data set. Two variables are provided for each of these analytes. The variable named ending in “LC” (ex., URDAAMLC) 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 analytic results below the lower limit of detection (ex., URDAAMLC=1), an imputed fill value was placed in the analyte results field. This value is the lower limit of detection divided by the square root of 2 (LLOD/sqrt [2]). The other variable prefixed URX (ex., URXAAM) provides the analytic result for the analyte.

The lower limit of detection (LLOD, in µg/L) for urine VOC metabolites:

 

VARIABLE

SAS LABEL

LLOD

URXAAM

 N-Acetyl-S-(2-carbamoylethyl)-L-cysteine

2.20

URXAMC

 N-Acetyl-S-(N-methylcarbamoyl)-L-cysteine

6.26

URXATC

 2-Aminothiazoline-4-carboxylic acid

15.0

URXBMA

 N-Acetyl-S-(benzyl)-L-cysteine

0.500

URXBPM

 N-Acetyl-S-(n-propyl)-L-cysteine

1.20

URXCEM

 N-Acetyl-S-(2-carboxyethyl)-L-cysteine

6.96

URXCYM

 N-Acetyl-S-(2-cyanoethyl)-L-cysteine

0.500

URX1DC

 N-Acetyl-S-(1,2-dichlorovinyl)-L-cysteine

12.6

URX2DC

 N-Acetyl-S-(2,2-dichlorovinyl)-L-cysteine

4.70

URXDHB

 N-Acetyl-S-(3,4-dihydroxybutyl)-L-cysteine

5.25

URXDPM

 N-Acetyl-S-(dimethylphenyl)-L-cysteine

0.500

URXGAM

 N-Acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine

9.40

URXHEM

 N-Acetyl-S-(2-hydroxyethyl)-L-cysteine

0.791

URXHPM

 N-Acetyl-S-(3-hydroxypropyl)-L-cysteine

13.0

URXHP2

 N-Acetyl-S-(2-hydroxypropyl)-L-cysteine

5.30

URXPMM

 N-Acetyl-S-(3-hydroxypropyl-1-methyl)-L-cysteine

2.00

URXMAD

 Mandelic acid

12.0

URX2MH

 2-Methylhippuric acid

5.00

URX34M

 3-and 4-Methylhippuric acid

8.00

URXMB1

 N-Acetyl-S-(1-hydroxymethyl-2-propenyl)-L-cysteine

0.700

URXMB2

 N-Acetyl-S-(2-hydroxy-3-butenyl)-L-cysteine

0.700

URXMB3

 N-Acetyl-S-(4-hydroxy-2-butenyl)-L-cysteine

0.600

URXPHE

 N-Acetyl-S-(phenyl-2-hydroxyethyl)-L-cysteine

0.700

URXPHG

 Phenylglyoxylic acid

12.0

URXPMA

 N-Acetyl-S-(phenyl)-L-cysteine

0.600

URXTCV

 N-Acetyl-S-(trichlorovinyl)-L-cysteine

3.00

URXTTC

 2-Thioxothiazolidine-4-carboxylic acid

11.2

 

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

WTSVOC2Y - VOC Subsample 2 yr MEC weight

Variable Name:
WTSVOC2Y
SAS Label:
VOC Subsample 2 yr MEC weight
English Text:
VOC Subsample 2 yr MEC weight
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
2483.4796553 to 325216.78843 Range of Values 3516 3516
0 No Lab Result 29 3545
. Missing 0 3545

URXUCR - Creatinine, urine (mg/dL)

Variable Name:
URXUCR
SAS Label:
Creatinine, urine (mg/dL)
English Text:
Creatinine, urine (mg/dL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
6 to 678 Range of Values 3430 3430
. Missing 115 3545

URX1DC - N-acel-S-(1,2-dichlorovinl)-L-cys(ng/mL)

Variable Name:
URX1DC
SAS Label:
N-acel-S-(1,2-dichlorovinl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(1,2-dichlorovinyl)-L-cysteine (ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
8.9 to 50 Range of Values 3349 3349
. Missing 196 3545

URD1DCLC - N-acel-S-(1,2-dichlorovinl)-L-cys comt

Variable Name:
URD1DCLC
SAS Label:
N-acel-S-(1,2-dichlorovinl)-L-cys comt
English Text:
N-acetyl-S-(1,2-dichlorovinyl)-L-cysteine 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 2 2
1 Below lower detection limit 3347 3349
. Missing 196 3545

URX2DC - N-acel-S-(2,2-Dichlorvinyl)-L-cys(ng/mL)

Variable Name:
URX2DC
SAS Label:
N-acel-S-(2,2-Dichlorvinyl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(2,2-Dichlorovinyl)-L-cysteine (ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3.32 to 28.1 Range of Values 3349 3349
. Missing 196 3545

URD2DCLC - N-acel-S-(2,2-Dichlorvinyl)-L-cys comt

Variable Name:
URD2DCLC
SAS Label:
N-acel-S-(2,2-Dichlorvinyl)-L-cys comt
English Text:
N-acetyl-S-(2,2-Dichlorovinyl)-L-cysteine 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 23 23
1 Below lower detection limit 3326 3349
. Missing 196 3545

URX2MH - 2-methylhippuric acid (ng/mL)

Variable Name:
URX2MH
SAS Label:
2-methylhippuric acid (ng/mL)
English Text:
2-methylhippuric acid (ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3.54 to 10300 Range of Values 3349 3349
. Missing 196 3545

URD2MHLC - 2-methylhippuric acid comment code

Variable Name:
URD2MHLC
SAS Label:
2-methylhippuric acid comment code
English Text:
2-methylhippuric 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 3169 3169
1 Below lower detection limit 180 3349
. Missing 196 3545

URX34M - 3-methipurc acd & 4-methipurc acd(ng/mL)

Variable Name:
URX34M
SAS Label:
3-methipurc acd & 4-methipurc acd(ng/mL)
English Text:
3-methylhippuric acid & 4-methylhippuric acid(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
5.66 to 125000 Range of Values 3349 3349
. Missing 196 3545

URD34MLC - 3-methipurc acd & 4-methipurc acid comt

Variable Name:
URD34MLC
SAS Label:
3-methipurc acd & 4-methipurc acid comt
English Text:
3-methylhippuric acid & 4-methylhippuric 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 3332 3332
1 Below lower detection limit 17 3349
. Missing 196 3545

URXAAM - N-ace-S-(2-carbamoylethyl)-L-cys(ng/mL)

Variable Name:
URXAAM
SAS Label:
N-ace-S-(2-carbamoylethyl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(2-carbamoylethyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1.56 to 2930 Range of Values 3349 3349
. Missing 196 3545

URDAAMLC - N-ace-S-(2-carbamoylethyl)-L-cys comt

Variable Name:
URDAAMLC
SAS Label:
N-ace-S-(2-carbamoylethyl)-L-cys comt
English Text:
N-acetyl-S-(2-carbamoylethyl)-L-cysteine 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 3314 3314
1 Below lower detection limit 35 3349
. Missing 196 3545

URXAMC - N-ace-S-(N-methlcarbamoyl)-L-cys(ng/mL)

Variable Name:
URXAMC
SAS Label:
N-ace-S-(N-methlcarbamoyl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(N-methylcarbamoyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
4.43 to 3070 Range of Values 3349 3349
. Missing 196 3545

URDAMCLC - N-ace-S-(N-methlcarbamoyl)-L-cys comt

Variable Name:
URDAMCLC
SAS Label:
N-ace-S-(N-methlcarbamoyl)-L-cys comt
English Text:
N-acetyl-S-(N-methylcarbamoyl)-L-cysteine 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 3296 3296
1 Below lower detection limit 53 3349
. Missing 196 3545

URXATC - 2-amnothiazolne-4-carbxylic acid(ng/mL)

Variable Name:
URXATC
SAS Label:
2-amnothiazolne-4-carbxylic acid(ng/mL)
English Text:
2-aminothiazoline-4-carboxylic acid(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
10.6 to 4480 Range of Values 3349 3349
. Missing 196 3545

URDATCLC - 2-amnothiazolne-4-carbxylic acid comt

Variable Name:
URDATCLC
SAS Label:
2-amnothiazolne-4-carbxylic acid comt
English Text:
2-amnothiazolne-4-carbxylic 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 2328 2328
1 Below lower detection limit 1021 3349
. Missing 196 3545

URXBMA - N-acetyl-S-(benzyl)-L-cysteine(ng/mL)

Variable Name:
URXBMA
SAS Label:
N-acetyl-S-(benzyl)-L-cysteine(ng/mL)
English Text:
N-acetyl-S-(benzyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.354 to 7930 Range of Values 3349 3349
. Missing 196 3545

URDBMALC - N-acetyl-S-(benzyl)-L-cysteine comt

Variable Name:
URDBMALC
SAS Label:
N-acetyl-S-(benzyl)-L-cysteine comt
English Text:
N-acetyl-S-(benzyl)-L-cysteine 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 3322 3322
1 Below lower detection limit 27 3349
. Missing 196 3545

URXBPM - N-acetyl-S-(n-propyl)-L-cysteine(ng/mL)

Variable Name:
URXBPM
SAS Label:
N-acetyl-S-(n-propyl)-L-cysteine(ng/mL)
English Text:
N-acetyl-S-(n-propyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.85 to 804 Range of Values 3349 3349
. Missing 196 3545

URDBPMLC - N-acetyl-S-(n-propyl)-L-cysteine comt

Variable Name:
URDBPMLC
SAS Label:
N-acetyl-S-(n-propyl)-L-cysteine comt
English Text:
N-acetyl-S-(n-propyl)-L-cysteine 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 2356 2356
1 Below lower detection limit 993 3349
. Missing 196 3545

URXCEM - N-acetyl-S-(2-Carbxyethyl)-L-cys(ng/mL)

Variable Name:
URXCEM
SAS Label:
N-acetyl-S-(2-Carbxyethyl)-L-cys(ng/mL)
English Text:
N-acetyl-S- (2-Carboxyethyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
4.92 to 3260 Range of Values 3349 3349
. Missing 196 3545

URDCEMLC - N-acetyl-S-(2-Carbxyethyl)-L-cys comt

Variable Name:
URDCEMLC
SAS Label:
N-acetyl-S-(2-Carbxyethyl)-L-cys comt
English Text:
N-acetyl-S- (2-Carboxyethyl)-L-cysteine 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 3279 3279
1 Below lower detection limit 70 3349
. Missing 196 3545

URXCYM - N-acetyl-S-(2-cyanoethyl)-L-cyst(ng/mL)

Variable Name:
URXCYM
SAS Label:
N-acetyl-S-(2-cyanoethyl)-L-cyst(ng/mL)
English Text:
N-acetyl-S-(2-cyanoethyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.354 to 1090 Range of Values 3349 3349
. Missing 196 3545

URDCYMLC - N-acetyl-S-(2-cyanoethyl)-L-cyst comt

Variable Name:
URDCYMLC
SAS Label:
N-acetyl-S-(2-cyanoethyl)-L-cyst comt
English Text:
N-acetyl-S-(2-cyanoethyl)-L-cysteine 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 3038 3038
1 Below lower detection limit 311 3349
. Missing 196 3545

URXDHB - N-ace-S-(3,4-Dihidxybutl)-L-cys(ng/mL)

Variable Name:
URXDHB
SAS Label:
N-ace-S-(3,4-Dihidxybutl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(3,4-Dihidroxybutyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3.71 to 4580 Range of Values 3349 3349
. Missing 196 3545

URDDHBLC - N-ace-S-(3,4-Dihidxybutl)-L-cys comt

Variable Name:
URDDHBLC
SAS Label:
N-ace-S-(3,4-Dihidxybutl)-L-cys comt
English Text:
N-acetyl-S-(3,4-Dihidroxybutyl)-L-cysteine 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 3337 3337
1 Below lower detection limit 12 3349
. Missing 196 3545

URXDPM - N-ace-S-(dimethylphenyl)-L-cys(ng/mL)

Variable Name:
URXDPM
SAS Label:
N-ace-S-(dimethylphenyl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(dimethylphenyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.354 to 3.28 Range of Values 3349 3349
. Missing 196 3545

URDDPMLC - N-ace-S-(dimethylphenyl)-L-cys comt

Variable Name:
URDDPMLC
SAS Label:
N-ace-S-(dimethylphenyl)-L-cys comt
English Text:
N-acetyl-S-(dimethylphenyl)-L-cysteine 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 9 9
1 Below lower detection limit 3340 3349
. Missing 196 3545

URXGAM - N-ac-S-(2-carbmo-2-hydxel)-L-cys(ng/mL)

Variable Name:
URXGAM
SAS Label:
N-ac-S-(2-carbmo-2-hydxel)-L-cys(ng/mL)
English Text:
N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
6.65 to 363 Range of Values 3349 3349
. Missing 196 3545

URDGAMLC - N-ac-S-(2-carbmo-2-hydxel)-L-cys comt

Variable Name:
URDGAMLC
SAS Label:
N-ac-S-(2-carbmo-2-hydxel)-L-cys comt
English Text:
N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine 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 2041 2041
1 Below lower detection limit 1308 3349
. Missing 196 3545

URXHEM - N-ace-S-(2-Hydroxyethyl)-L-cys(ng/mL)

Variable Name:
URXHEM
SAS Label:
N-ace-S-(2-Hydroxyethyl)-L-cys(ng/mL)
English Text:
N-acetyl-S- (2-Hydroxyethyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.559 to 37.4 Range of Values 3349 3349
. Missing 196 3545

URDHEMLC - N-ace-S-(2-Hydroxyethyl)-L-cys comt

Variable Name:
URDHEMLC
SAS Label:
N-ace-S-(2-Hydroxyethyl)-L-cys comt
English Text:
N-acetyl-S- (2-Hydroxyethyl)-L-cysteine 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 1004 1004
1 Below lower detection limit 2345 3349
. Missing 196 3545

URXHP2 - N-ace-S-(2-hydroxypropyl)-L-cys(ng/mL)

Variable Name:
URXHP2
SAS Label:
N-ace-S-(2-hydroxypropyl)-L-cys(ng/mL)
English Text:
N-acetyl-S- (2-hydroxypropyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3.75 to 6470 Range of Values 3349 3349
. Missing 196 3545

URDHP2LC - N-ace-S-(2-hydroxypropyl)-L-cys comt

Variable Name:
URDHP2LC
SAS Label:
N-ace-S-(2-hydroxypropyl)-L-cys comt
English Text:
N-acetyl-S-(2-hydroxypropyl)-L-cysteine 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 3153 3153
1 Below lower detection limit 196 3349
. Missing 196 3545

URXHPM - N-ace-S-(3-Hydroxypropyl)-L-cys(ng/mL)

Variable Name:
URXHPM
SAS Label:
N-ace-S-(3-Hydroxypropyl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(3-Hydroxypropyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
9.2 to 7010 Range of Values 3349 3349
. Missing 196 3545

URDHPMLC - N-ace-S-(3-Hydroxypropyl)-L-cys comt

Variable Name:
URDHPMLC
SAS Label:
N-ace-S-(3-Hydroxypropyl)-L-cys comt
English Text:
N-acetyl-S-(3-Hydroxypropyl)-L-cysteine 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 3312 3312
1 Below lower detection limit 37 3349
. Missing 196 3545

URXPMM - N-a-s-(3-hydrxprpl-1-metl)-L-cys(ng/mL)

Variable Name:
URXPMM
SAS Label:
N-a-s-(3-hydrxprpl-1-metl)-L-cys(ng/mL)
English Text:
N-acetyl-s-(3-hydroxypropyl-1-methyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1.4 to 14300 Range of Values 3349 3349
. Missing 196 3545

URDPMMLC - N-a-s-(3-hydrxprpl-1-metl)-L-cys comt

Variable Name:
URDPMMLC
SAS Label:
N-a-s-(3-hydrxprpl-1-metl)-L-cys comt
English Text:
N-acetyl-s-(3-hydroxypropyl-1-methyl)-L-cysteine 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 3344 3344
1 Below lower detection limit 5 3349
. Missing 196 3545

URXMAD - Mandelic acid(ng/mL)

Variable Name:
URXMAD
SAS Label:
Mandelic acid(ng/mL)
English Text:
Mandelic acid(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
8.5 to 75900 Range of Values 3349 3349
. Missing 196 3545

URDMADLC - Mandelic acid comment code

Variable Name:
URDMADLC
SAS Label:
Mandelic acid comment code
English Text:
Mandelic 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 3309 3309
1 Below lower detection limit 40 3349
. Missing 196 3545

URXMB3 - N-a-s-(4-hydrxy-2butn-l-yl)-L-cys(ng/mL)

Variable Name:
URXMB3
SAS Label:
N-a-s-(4-hydrxy-2butn-l-yl)-L-cys(ng/mL)
English Text:
N-acetyl-s-(4-hydroxy-2-butenyl)-L-cysteine (ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.424 to 377 Range of Values 3349 3349
. Missing 196 3545

URDMB3LC - N-a-s-(4-hydrxy-2butn-l-yl)-L-cys comt

Variable Name:
URDMB3LC
SAS Label:
N-a-s-(4-hydrxy-2butn-l-yl)-L-cys comt
English Text:
N-acetyl-s-(4-hydroxy-2-butenyl)-L-cysteine 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 3254 3254
1 Below lower detection limit 95 3349
. Missing 196 3545

URXMB2 - N-ac-s-(2-hydrxy-3-butnyl)-L-cys(ng/mL)

Variable Name:
URXMB2
SAS Label:
N-ac-s-(2-hydrxy-3-butnyl)-L-cys(ng/mL)
English Text:
N-acetyl-s-(2-hydroxy-3-butenyl)-L-cysteine (ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.495 to 18.5 Range of Values 3349 3349
. Missing 196 3545

URDMB2LC - N-ac-s-(2-Hydrxy-3-butnyl)-L-cys comt

Variable Name:
URDMB2LC
SAS Label:
N-ac-s-(2-Hydrxy-3-butnyl)-L-cys comt
English Text:
N-acetyl-S-(2-hydroxy-3-butenyl)-L-cysteine 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 403 403
1 Below lower detection limit 2946 3349
. Missing 196 3545

URXMB1 - N-a-s-(1-hydrxMet)-2-prpn)-L-cys(ng/mL)

Variable Name:
URXMB1
SAS Label:
N-a-s-(1-hydrxMet)-2-prpn)-L-cys(ng/mL)
English Text:
N-acetyl-s-(1-hydroxyMethyl)-2-propenyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.495 to 4.59 Range of Values 3349 3349
. Missing 196 3545

URDMB1LC - N-a-s-(1-hydrxMet)-2-prpn)-L-cys comt

Variable Name:
URDMB1LC
SAS Label:
N-a-s-(1-hydrxMet)-2-prpn)-L-cys comt
English Text:
N-acetyl-s-(1-hydroxyMethyl)-2-propenyl)-L-cysteine 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 26 26
1 Below lower detection limit 3323 3349
. Missing 196 3545

URXPHE - N-ace-s-(phenl-2-hydxyetl)-L-cys(ng/mL)

Variable Name:
URXPHE
SAS Label:
N-ace-s-(phenl-2-hydxyetl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(phenyl-2-hydroxyethyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.495 to 66.9 Range of Values 3349 3349
. Missing 196 3545

URDPHELC - N-ace-s-(phenl-2-hydxyetl)-L-cys comt

Variable Name:
URDPHELC
SAS Label:
N-ace-s-(phenl-2-hydxyetl)-L-cys comt
English Text:
N-acetyl-S-(phenyl-2-hydroxyethyl)-L-cysteine 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 274 274
1 Below lower detection limit 3075 3349
. Missing 196 3545

URXPHG - Phenylglyoxylic acid(ng/mL)

Variable Name:
URXPHG
SAS Label:
Phenylglyoxylic acid(ng/mL)
English Text:
Phenylglyoxylic acid(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
8.5 to 74900 Range of Values 3349 3349
. Missing 196 3545

URDPHGLC - Phenylglyoxylic acid comment code

Variable Name:
URDPHGLC
SAS Label:
Phenylglyoxylic acid comment code
English Text:
Phenylglyoxylic 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 2824 2824
1 Below lower detection limit 525 3349
. Missing 196 3545

URXPMA - N-acetyl-s-(phenyl)-L-cysteine(ng/mL)

Variable Name:
URXPMA
SAS Label:
N-acetyl-s-(phenyl)-L-cysteine(ng/mL)
English Text:
N-acetyl-s-(phenyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.424 to 37.5 Range of Values 3349 3349
. Missing 196 3545

URDPMALC - N-acetyl-s-(phenyl)-L-cysteine comt

Variable Name:
URDPMALC
SAS Label:
N-acetyl-s-(phenyl)-L-cysteine comt
English Text:
N-acetyl-s-(phenyl)-L-cysteine 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 698 698
1 Below lower detection limit 2651 3349
. Missing 196 3545

URXTCV - N-acetyl-s-(trichlorovinyl)-L-cys(ng/mL)

Variable Name:
URXTCV
SAS Label:
N-acetyl-s-(trichlorovinyl)-L-cys(ng/mL)
English Text:
N-acetyl-s-(trichlorovinyl)-L-cysteine(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
2.12 to 16.1 Range of Values 3349 3349
. Missing 196 3545

URDTCVLC - N-acetyl-s-(trichlorovinyl)-L-cys comt

Variable Name:
URDTCVLC
SAS Label:
N-acetyl-s-(trichlorovinyl)-L-cys comt
English Text:
N-acetyl-s-(trichlorovinyl)-L-cysteine 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 2 2
1 Below lower detection limit 3347 3349
. Missing 196 3545

URXTTC - 2-thoxothazlidne-4-carbxylic acid(ng/mL)

Variable Name:
URXTTC
SAS Label:
2-thoxothazlidne-4-carbxylic acid(ng/mL)
English Text:
2-thioxothiazolidine-4-carboxylic acid(ng/mL)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7.92 to 2920 Range of Values 3349 3349
. Missing 196 3545

URDTTCLC - 2-thoxothazlidne-4-carbxylic comt

Variable Name:
URDTTCLC
SAS Label:
2-thoxothazlidne-4-carbxylic comt
English Text:
2-thioxothiazolidine-4-carboxylic 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 1284 1284
1 Below lower detection limit 2065 3349
. Missing 196 3545