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

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

Several systematic biases were discovered in measurements of certain urinary VOC metabolites in the 2005 – 2006 and 2011 – 2012 NHANES cycles. Upon further investigation, in April 2022, the following adjustments have been applied to the previously published data and included in the present dataset.

A. Adjustment to correct calibrator errors of the CDC lab prepared calibration materials

During the 2005–2006 and 2011–2012 NHANES cycles, calibrators used for tests on several VOC metabolites were prepared from a multi-analyte stock solution formulated from neat materials prepared by the testing lab at CDC. Beginning with the NHANES 2015–2016 cycle, calibrators and the multi-analyte stock solution were prepared externally. A systematic bias was observed between the cycles that used in-house calibration materials and the cycle using externally prepared calibration materials. 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 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

Validations of the externally prepared calibrators suggested that the calibrators previously prepared by the CDC testing lab were inaccurate due to special requirements for handling and preparing accurate solutions from neat materials, some of which are highly hygroscopic. Below is the list of analytes affected and the corresponding adjustment factors used in correction equation.

Analyte 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 -0.0746
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 m used in correction
URXHP2 0.5471199
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 m used in correction b used in correction
URXMB3 0.97741 -0.18775

 

B. Adjustment to correct calibrator errors of calibration materials prepared by an external vendor

Correction of N-Acetyl-S-(3-Hydroxypropyl-1-Methyl)-L-Cysteine (URXPMM)

In the 2005-2006 and 2011-2016 NHANES cycles, calibrators used to test N-Acetyl-S-(3-hydroxypropyl-1-methyl)-L-cysteine (URXPMM) were externally prepared, by a vendor, from a multi-analyte stock solution formulated from neat materials. In 2021, accuracy solutions from a new vendor indicated a systematic bias. Validations conducted by the CDC testing lab confirmed that the large mass fraction of salt in the neat materials was not accounted for during formulation of the externally prepared calibration materials from the previous vendor. This discrepancy between the calculated concentration of the calibrators and the actual concentration led to a systematic bias in results for URXPMM. An algebraic correction factor of 0.565 were applied to the original URXPMM values and released in the present file as below:

URXPMM = URXPMMOriginal × 0.565

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 2.2
URXAMC  N-Acetyl-S-(N-methylcarbamoyl)-L-cysteine 6.26
URXATC  2-Aminothiazoline-4-carboxylic acid 15
URXBMA  N-Acetyl-S-(benzyl)-L-cysteine 0.5
URXBPM  N-Acetyl-S-(n-propyl)-L-cysteine 1.2
URXCEM  N-Acetyl-S-(2-carboxyethyl)-L-cysteine 6.96
URXCYM  N-Acetyl-S-(2-cyanoethyl)-L-cysteine 0.5
URX1DC  N-Acetyl-S-(1,2-dichlorovinyl)-L-cysteine 12.6
URX2DC  N-Acetyl-S-(2,2-dichlorovinyl)-L-cysteine 4.7
URXDHB  N-Acetyl-S-(3,4-dihydroxybutyl)-L-cysteine 5.25
URXDPM  N-Acetyl-S-(dimethylphenyl)-L-cysteine 0.5
URXGAM  N-Acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine 9.4
URXHEM  N-Acetyl-S-(2-hydroxyethyl)-L-cysteine 0.791
URXHPM  N-Acetyl-S-(3-hydroxypropyl)-L-cysteine 13
URXHP2  N-Acetyl-S-(2-hydroxypropyl)-L-cysteine 5.3
URXPMM  N-Acetyl-S-(3-hydroxypropyl-1-methyl)-L-cysteine 1.13
URXMAD  Mandelic acid 12
URX2MH  2-Methylhippuric acid 5
URX34M  3-and 4-Methylhippuric acid 8
URXMB1  N-Acetyl-S-(1-hydroxymethyl-2-propenyl)-L-cysteine 0.7
URXMB2  N-Acetyl-S-(2-hydroxy-3-butenyl)-L-cysteine 0.7
URXMB3  N-Acetyl-S-(4-hydroxy-2-butenyl)-L-cysteine 0.6
URXPHE  N-Acetyl-S-(phenyl-2-hydroxyethyl)-L-cysteine 0.7
URXPHG  Phenylglyoxylic acid 12
URXPMA  N-Acetyl-S-(phenyl)-L-cysteine 0.6
URXTCV  N-Acetyl-S-(trichlorovinyl)-L-cysteine 3
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
2605.678075 to 325216.78843 Range of Values 3300 3300
0 No Lab Result 17 3317
. Missing 0 3317

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 3244 3244
. Missing 73 3317

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 3169 3169
. Missing 148 3317

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 3167 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 22 22
1 Below lower detection limit 3147 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 2999 2999
1 Below lower detection limit 170 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 3152 3152
1 Below lower detection limit 17 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 3135 3135
1 Below lower detection limit 34 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 3117 3117
1 Below lower detection limit 52 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 2198 2198
1 Below lower detection limit 971 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 3143 3143
1 Below lower detection limit 26 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 2218 2218
1 Below lower detection limit 951 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 3102 3102
1 Below lower detection limit 67 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 2870 2870
1 Below lower detection limit 299 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 3158 3158
1 Below lower detection limit 11 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 3160 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 1937 1937
1 Below lower detection limit 1232 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 942 942
1 Below lower detection limit 2227 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 2980 2980
1 Below lower detection limit 189 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 3133 3133
1 Below lower detection limit 36 3169
. Missing 148 3317

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
0.8 to 8080 Range of Values 3169 3169
. Missing 148 3317

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 3164 3164
1 Below lower detection limit 5 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 3133 3133
1 Below lower detection limit 36 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 3079 3079
1 Below lower detection limit 90 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 381 381
1 Below lower detection limit 2788 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 3143 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 260 260
1 Below lower detection limit 2909 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 2665 2665
1 Below lower detection limit 504 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 661 661
1 Below lower detection limit 2508 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 3167 3169
. Missing 148 3317

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 3169 3169
. Missing 148 3317

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 1221 1221
1 Below lower detection limit 1948 3169
. Missing 148 3317