Table of Contents

Locator Record

Title: Urine Heavy Metals (UHM_E )
Contact Number: 1-866-441-NCHS
Years of Content: 2007 - 2008
First Published: September, 2009
Revised: September, 2011
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:Heavy metals, Multi-analyte profile
Record Source: NHANES 2007 - 2008
Survey Methodology: NHANES 2007 - 2008 is a stratified multistage probability sample of the civilian non-institutionalized population of the U.S.
Medium: NHANES Web site; SAS transport files

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 6 years and older, who met the subsample requirements, were eligible.

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 K. 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), barium (Ba), tungsten (W), platinum (Pt), 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.

A detailed description of the laboratory methods used can be found on the NHANES website.

Laboratory Quality Assurance and Monitoring

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 Act mandates. Detailed QA/QC instructions are discussed in the NHANES LPM.

Analytical Laboratories

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

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

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

Analytic Notes

Subsample weights

Urinary heavy metals were measured in a one third subsample of persons 6 years and over. Special sample weights are required to analyze these data properly. Specific sample weights for this subsample are included in this data file and should be used when analyzing these data.

Variance estimation

The analysis of NHANES 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 2007-2008 data files using the unique survey participant identifier SEQN.

Detection Limits

The lower detection limits for all analytes were constant during this two-year cycle. The detection limit divided by the square root of 2 is the value that is provided for results that are below the limit of detection.

Please refer to the Analytic Guidelines for further details on the use of sample weights and other analytic issues. The Analytic Guidelines are available on the NHANES website.

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 6 YEARS - 150 YEARS

WTSA2YR - Two-year A subsample weights

Variable Name:
WTSA2YR
SAS Label:
Two-year A subsample weights
English Text:
Two-year A subsample weights
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 604864.71127 Range of Values 2720 2720
. Missing 0 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7 to 528 Range of Values 2657 2657
. Missing 63 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.08 to 101 Range of Values 2627 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2602 2602
1 Below lower detection limit 25 2627
. Missing 93 2720

URXUBE - Beryllium, urine (ug/L)

Variable Name:
URXUBE
SAS Label:
Beryllium, urine (ug/L)
English Text:
Beryllium, urine (ug/L)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.051 to 0.705 Range of Values 2627 2627
. Missing 93 2720

URDUBELC - Urinary Beryllium comment code

Variable Name:
URDUBELC
SAS Label:
Urinary Beryllium comment code
English Text:
Urinary Beryllium comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 10 10
1 Below lower detection limit 2617 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.03 to 4.72 Range of Values 2627 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2361 2361
1 Below lower detection limit 266 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.029 to 11.9 Range of Values 2627 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2621 2621
1 Below lower detection limit 6 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.214 to 92.5 Range of Values 2627 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2627 2627
1 Below lower detection limit 0 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.65 to 827 Range of Values 2627 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2625 2625
1 Below lower detection limit 2 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.07 to 52.3 Range of Values 2627 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2575 2575
1 Below lower detection limit 52 2627
. Missing 93 2720

URXUPT - Platinum, urine (ug/L)

Variable Name:
URXUPT
SAS Label:
Platinum, urine (ug/L)
English Text:
Platinum, urine (ug/L)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.006 to 7.13 Range of Values 2627 2627
. Missing 93 2720

URDUPTLC - Urinary Platinum comment code

Variable Name:
URDUPTLC
SAS Label:
Urinary Platinum comment code
English Text:
Urinary Platinum comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 146 146
1 Below lower detection limit 2481 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.023 to 5.59 Range of Values 2627 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2126 2126
1 Below lower detection limit 501 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.011 to 3.49 Range of Values 2627 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2613 2613
1 Below lower detection limit 14 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.015 to 33.07 Range of Values 2627 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2438 2438
1 Below lower detection limit 189 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.0012 to 1.412 Range of Values 2627 2627
. Missing 93 2720

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 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2430 2430
1 Below lower detection limit 197 2627
. Missing 93 2720