Table of Contents

Component Description

Trace metals have been associated with adverse health effects in occupational studies or laboratory studies, but have not been monitored in general population groups.

This method is used to achieve rapid and accurate quantifications of multiple elements of toxicological and nutritional interest. The method is sensitive and rapid enough to screen urine specimens from subjects suspected to be exposed to a number of important toxic elements, or to evaluate environmental or other nonoccupationally exposure to these same elements.

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

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 specimen collection and processing instructions are discussed in the NHANES Laboratory/Medical Technologists Procedures Manual (LPM). Read the General Documentation on Laboratory Data file for detailed data processing and editing protocols.

Inductively coupled plasma-mass spectrometry (ICP-MS) is a multi-element analytical technique (Date AR, et al., 1989). Liquid samples are introduced into the ICP through a nebulizer and spray chamber carried by a flowing argon stream. By coupling radio-frequency power into flowing argon, plasma is created in which the predominant species are positive argon ions and electrons. The sample passes through a region of the plasma that has a temperature of 6000–8000 ºK. The thermal energy atomizes the sample and then ionizes the atoms. The ions, along with the argon, enter the mass spectrometer through an interface that separates the ICP from the mass spectrometer, which is operating at an atmospheric pressure of 10–5 torr. The mass spectrometer permits ions at each mass to be detected in rapid sequence, allowing individual isotopes of an element to be determined. Electrical signals resulting from the detection of the ions are processed into digital information that is used to indicate first the intensity of the ions and then the concentration of the element. The ICP-MS method is used to measure the following 12 elements in urine: beryllium (Be), cobalt (Co), molybdenum (Mo), cadmium (Cd), antimony (Sb), cesium (Cs), tungsten (W), tin (Sn), strontium(Sr), manganese(Mn), thallium (TI), lead (Pb), and uranium (U). This method is based on the method by (Mulligan KJ, et al. 1990) Urine samples are diluted 1+9 with 2% (v/v), double-distilled, concentrated nitric acid containing both iridium (Ir) and rhodium (Rh) for multi-internal standardization. This procedure can be used for all 12 elements or for subsets of the 12 elements.

There were no changes (from the previous 2 years of NHANES) to equipment, lab methods or lab site.

Detailed instructions on specimen collection and processing can be found in the NHANES Laboratory/Medical Technologists Procedures Manual (LPM).

Data Processing and Editing

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

Laboratory Quality Assurance and Monitoring

The NHANES quality control and quality assurance protocols (QA/QC) meet the 1988 Clinical Laboratory Improvement Act mandates. Detailed QA/QC instructions are discussed in the NHANES Laboratory/Medical Technologists Procedures Manual (LPM).

Analytic Notes

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

Subsample Weights

Urinary heavy metals were measured in a smoking sample of persons 20 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 heavy metals in the data set.
Lower detection limits for the heavy metals in the data set:
Urinary Barium= 0.10 µg/L

Urinary Cadmium= 0.056 µg/L

Urinary Cobalt= 0.048 µg/L

Urinary Magnanese=0.08 µg/L

Urinary Lead= 0.08 µg/L

Urinary Antimony= 0.041 ug/L

Urinary Molybdenum= 0.99 ug/L

Urinary Cesium= 0.12 ug/L

Urinary Strontium=2.50 µg/L

Urinary Thallium= 0.020 ug/L

Urinary Tin=0.22 µg/L

Urinary Tungsten= 0.026 ug/L

Urinary Uranium= 0.0033 ug/L

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. In cases where the result was below the limit of detection, the value for that variable is the detection limit divided by the square root of two.

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

References

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 700606.65 Range of Values 2349 2349
. Missing 0 2349

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 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

URXUBA - Barium, urine (ug/L)

Variable Name:
URXUBA
SAS Label:
Barium, urine (ug/L)
English Text:
Barium, urine (ug/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.07 to 129 Range of Values 2272 2272
. Missing 77 2349

URDUBALC - Urinary Barium comment code

Variable Name:
URDUBALC
SAS Label:
Urinary Barium comment code
English Text:
Urinary Barium 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 2252 2252
1 Below lower detection limit 20 2272
. Missing 77 2349

URXUCD - Cadmium, urine (ug/L)

Variable Name:
URXUCD
SAS Label:
Cadmium, urine (ug/L)
English Text:
Cadmium, urine (ug/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.04 to 6.94 Range of Values 2272 2272
. Missing 77 2349

URDUCDLC - Urinary Cadmium comment code

Variable Name:
URDUCDLC
SAS Label:
Urinary Cadmium comment code
English Text:
Urinary Cadmium 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 2052 2052
1 Below lower detection limit 220 2272
. Missing 77 2349

URXUCO - Cobalt, urine (ug/L)

Variable Name:
URXUCO
SAS Label:
Cobalt, urine (ug/L)
English Text:
Cobalt, urine (ug/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.034 to 31 Range of Values 2271 2271
. Missing 78 2349

URDUCOLC - Urinary Cobalt (ug/L) comment code

Variable Name:
URDUCOLC
SAS Label:
Urinary Cobalt (ug/L) comment code
English Text:
Urinary Cobalt (ug/L) 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 2255 2255
1 Below lower detection limit 16 2271
. Missing 78 2349

URXUCS - Cesium, urine (ug/L)

Variable Name:
URXUCS
SAS Label:
Cesium, urine (ug/L)
English Text:
Cesium, urine (ug/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.21 to 49.9 Range of Values 2271 2271
. Missing 78 2349

URDUCSLC - Urinary Cesium comment code

Variable Name:
URDUCSLC
SAS Label:
Urinary Cesium comment code
English Text:
Urinary Cesium 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 2271 2271
1 Below lower detection limit 0 2271
. Missing 78 2349

URXUMO - Molybdenum, urine (ug/L)

Variable Name:
URXUMO
SAS Label:
Molybdenum, urine (ug/L)
English Text:
Molybdenum, urine (ug/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1.39 to 550 Range of Values 2272 2272
. Missing 77 2349

URDUMOLC - Urinary Molybdenum comment code

Variable Name:
URDUMOLC
SAS Label:
Urinary Molybdenum comment code
English Text:
Urinary Molybdenum 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 2272 2272
1 Below lower detection limit 0 2272
. Missing 77 2349

URXUMN - Manganese, urine (ug/L)

Variable Name:
URXUMN
SAS Label:
Manganese, urine (ug/L)
English Text:
Manganese, urine (ug/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.057 to 4.28 Range of Values 2272 2272
. Missing 77 2349

URDUMNLC - Urinary Mn comment code

Variable Name:
URDUMNLC
SAS Label:
Urinary Mn comment code
English Text:
Urinary Mn 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 1537 1537
1 Below lower detection limit 735 2272
. Missing 77 2349

URXUPB - Lead, urine (ug/L)

Variable Name:
URXUPB
SAS Label:
Lead, urine (ug/L)
English Text:
Lead, urine (ug/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.06 to 35 Range of Values 2272 2272
. Missing 77 2349

URDUPBLC - Urinary Lead comment code

Variable Name:
URDUPBLC
SAS Label:
Urinary Lead comment code
English Text:
Urinary Lead 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 2196 2196
1 Below lower detection limit 76 2272
. Missing 77 2349

URXUSB - Antimony, urine (ug/L)

Variable Name:
URXUSB
SAS Label:
Antimony, urine (ug/L)
English Text:
Antimony, urine (ug/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.029 to 2.72 Range of Values 2272 2272
. Missing 77 2349

URDUSBLC - Urinary Antimony comment code

Variable Name:
URDUSBLC
SAS Label:
Urinary Antimony comment code
English Text:
Urinary Antimony 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 1352 1352
1 Below lower detection limit 920 2272
. Missing 77 2349

URXUSN - Tin, urine (ug/L)

Variable Name:
URXUSN
SAS Label:
Tin, urine (ug/L)
English Text:
Tin, urine (ug/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.156 to 219.64 Range of Values 2272 2272
. Missing 77 2349

URDUSNLC - USN comment code

Variable Name:
URDUSNLC
SAS Label:
USN comment code
English Text:
USN 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 1923 1923
1 Below lower detection limit 349 2272
. Missing 77 2349

URXUSR - Strontium, urine (ug/L)

Variable Name:
URXUSR
SAS Label:
Strontium, urine (ug/L)
English Text:
Strontium, urine (ug/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1.768 to 5801.79 Range of Values 2269 2269
. Missing 80 2349

URDUSRLC - USR comment code

Variable Name:
URDUSRLC
SAS Label:
USR comment code
English Text:
USR 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 2268 2268
1 Below lower detection limit 1 2269
. Missing 80 2349

URXUTL - Thallium, urine (ug/L)

Variable Name:
URXUTL
SAS Label:
Thallium, urine (ug/L)
English Text:
Thallium, urine (ug/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.014 to 1.37 Range of Values 2272 2272
. Missing 77 2349

URDUTLLC - Urinary Thallium comment code

Variable Name:
URDUTLLC
SAS Label:
Urinary Thallium comment code
English Text:
Urinary Thallium 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 2255 2255
1 Below lower detection limit 17 2272
. Missing 77 2349

URXUTU - Tungsten, urine (ug/L)

Variable Name:
URXUTU
SAS Label:
Tungsten, urine (ug/L)
English Text:
Tungsten, urine (ug/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.018 to 32.91 Range of Values 2256 2256
. Missing 93 2349

URDUTULC - Urinary Tungsten comment code

Variable Name:
URDUTULC
SAS Label:
Urinary Tungsten comment code
English Text:
Urinary Tungsten 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 1882 1882
1 Below lower detection limit 374 2256
. Missing 93 2349

URXUUR - Uranium, urinary (ug/L)

Variable Name:
URXUUR
SAS Label:
Uranium, urinary (ug/L)
English Text:
Uranium, urinary (ug/L)
Target:
Both males and females 20 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.0023 to 1.151 Range of Values 2272 2272
. Missing 77 2349

URDUURLC - Urinary Uranium comment code

Variable Name:
URDUURLC
SAS Label:
Urinary Uranium comment code
English Text:
Urinary Uranium 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 1683 1683
1 Below lower detection limit 589 2272
. Missing 77 2349