Table of Contents

Locator Record

Title: Urinary Heavy Metal (UHM_D )
Contact Number: 1-866-441-NCHS
Years of Content: 2005 - 2006
First Published: October, 2008
Revised: NA
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:Heavy Metals
Record Source: NHANES 2005 - 2006
Survey Methodology: NHANES 2005 - 2006 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 nonoccupational exposure to these same elements.

Eligible Sample

Participants aged 6 years and older who met the subsample requirements.

Description of Laboratory Methodology

Inductively coupled plasma-mass spectrometry (ICP-MS) is a multi-element analytical technique (Date 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 6000–8000ºK. 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 et al. 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 subsets of the 12 elements.

Laboratory Quality Assurance and Monitoring

Urine specimens are processed, stored, and shipped to the Division of Environmental Health Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention for analysis.

Detailed specimen collection and processing instructions are discussed in the NHANES Laboratory/Medical Technologists Procedures Manual (LPM). Vials are stored under appropriate frozen (–20°C) conditions until they are shipped to National Center for Environmental Health for testing.

Mobile Examination Centers (MECs)

Laboratory team performance is monitored using several techniques. NCHS and contract consultants use a structured quality assurance evaluation during unscheduled visits to evaluate both the quality of the laboratory work and the quality-control procedures. Each laboratory staff person is observed for equipment operation, specimen collection and preparation; testing procedures and constructive feedback are given to each staff. Formal retraining sessions are conducted annually to ensure that required skill levels were maintained.

The NHANES QA/QC protocols meet the 1988 Clinical Laboratory Improvement 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

Measures of 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 2005-2006 laboratory data must be conducted with the key survey design and basic demographic variables. The NHANES 2005-2006 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 2005-2006 data files using the unique survey participant identifier SEQN.

Detection Limits

The detection limit was constant for all of the analytes in the data set. Two variables are provided for each of these analytes. 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. The other variable named LBX___ provides the analytic result for that analyte. 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.

URXUCD and URDUCD:

When comparing urine cadmium across two-year cycles please note that even though these two variables have different names the data is comparable. Variable URXUCD is used in 1999-2000, 2003-2004, and 2005-2006 and variable URDUCD was used in 2001-2002. Variable URDUCD was derived to correct for molybdenum interference (Reference to 2001-2002 lab 6 heavy metal documentation). Beginning in 2003-2004 the urinary cadmium data is corrected at the testing laboratory for molybdenum interference.

Please refer to the Analytic Guidelines 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 6 YEARS - 150 YEARS

WTSA2YR - Two-year MEC weights of subsample A

Variable Name:
WTSA2YR
SAS Label:
Two-year MEC weights of subsample A
English Text:
Two-year MEC weights of subsample A
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 412940.77909 Range of Values 2692 2692
. Missing 0 2692

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 534 Range of Values 2608 2608
. Missing 84 2692

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 85.7 Range of Values 2576 2576
. Missing 116 2692

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 2547 2547
1 Below lower detection limit 29 2576
. Missing 116 2692

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 0.08 Range of Values 2576 2576
. Missing 116 2692

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 5 5
1 Below lower detection limit 2571 2576
. Missing 116 2692

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 5.35 Range of Values 2576 2576
. Missing 116 2692

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 2316 2316
1 Below lower detection limit 260 2576
. Missing 116 2692

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 39.8 Range of Values 2576 2576
. Missing 116 2692

URDUCOLC - Urinary Cobalt comment code

Variable Name:
URDUCOLC
SAS Label:
Urinary Cobalt comment code
English Text:
Urinary Cobalt 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 2566 2566
1 Below lower detection limit 10 2576
. Missing 116 2692

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
0.191 to 63.7 Range of Values 2576 2576
. Missing 116 2692

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 2576 2576
1 Below lower detection limit 0 2576
. Missing 116 2692

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
1.61 to 1230 Range of Values 2576 2576
. Missing 116 2692

URDUMOLC - Urinary Molybden comment code

Variable Name:
URDUMOLC
SAS Label:
Urinary Molybden comment code
English Text:
Urinary Molybden 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 2576 2576
1 Below lower detection limit 0 2576
. Missing 116 2692

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 71.7 Range of Values 2576 2576
. Missing 116 2692

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 2515 2515
1 Below lower detection limit 61 2576
. Missing 116 2692

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 697 Range of Values 2576 2576
. Missing 116 2692

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 310 310
1 Below lower detection limit 2266 2576
. Missing 116 2692

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 47 Range of Values 2576 2576
. Missing 116 2692

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 2233 2233
1 Below lower detection limit 343 2576
. Missing 116 2692

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 1.68 Range of Values 2576 2576
. Missing 116 2692

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 2573 2573
1 Below lower detection limit 3 2576
. Missing 116 2692

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 20.11 Range of Values 2576 2576
. Missing 116 2692

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 2382 2382
1 Below lower detection limit 194 2576
. Missing 116 2692

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 0.633 Range of Values 2576 2576
. Missing 116 2692

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 2392 2392
1 Below lower detection limit 184 2576
. Missing 116 2692