Table of Contents

Locator Record

Title: Total and Speciated Arsenics (L06UAS_C )
Contact Number: 1-866-441-NCHS
Years of Content: 2003 - 2004
First Published: November, 2007
Revised: NA
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:Total and Speciated Arsenics
Record Source: NHANES 2003 - 2004
Survey Methodology: NHANES 2003 - 2004 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

Arsenic is widely distributed in the earth’s crust and is found most often in ground water rather than surface water. People encounter arsenic in many chemical forms that vary greatly in toxicity. The most toxic of the naturally-occurring arsenic compounds are inorganic forms of arsenic and their methylated metabolites. Less toxic are the organic arsenic compounds. Although this method does not reveal the chemical form of arsenic to which a person is exposed, it is sensitive enough to screen urine specimens rapidly from people thought to be exposed to arsenic or to evaluate total environmental or other total non-occupational exposure to arsenic.

Eligible Sample

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

Description of Laboratory Methodology

1. Total arsenic

The method described in this manual assesses arsenic exposure by analyzing urine through the use of inductively coupled-plasma dynamic reaction cell-mass spectrometry (ICP-DRC-MS). Urine is analyzed because urinary excretion is the major pathway for eliminating arsenic from the mammalian body. This method achieves rapid and accurate quantification of total urinary arsenic.

Total urine arsenic concentrations are determined by using ICP-DRC- MS. This multielement analytical technique is based on quadrupole ICP-MS technology and includes DRC™ technology, which minimizes or eliminates much argon-based polyatomic interference. Coupling radio frequency power into a flowing argon stream seeded with electrons creates the plasma, the heat source, which is ionized gas suspended in a magnetic field. Predominant species in the plasma are positive argon ions and electrons. Diluted urine samples are converted into an aerosol by using a nebulizer inserted within a spray chamber. A portion of the aerosol is transported through the spray chamber and then through the central channel of the plasma, where it is exposed to temperatures of 6000-8000ºK. This thermal energy atomizes and ionizes the sample. The ions and the argon enter the mass spectrometer through an interface that separates the ICP, which is operating at atmospheric pressure (approximately 760 torr), from the mass spectrometer, which is operating at approximately 10-5 torr. The mass spectrometer permits detection of ions at each mass-to-charge ratio in rapid sequence, which allowsthe determination of individual isotopes of an element. Once inside the mass spectrometer, the ions pass through the ion optics, then through DRC™, and finally through the mass-analyzing quadrupole before being detected as they strike the surface of the detector. The ion optics uses an electrical field to focus the ion beam into the DRC™. The DRC™ component is pressurized with an appropriate reaction gas and contains a quadrupole. In the DRC™, elimination or reduction of argon-based polyatomic interferences takes place through the interaction of the reaction gas with the interfering polyatomic species in the incoming ion beam. The quadrupole in the DRC™ allows elimination of unwanted reaction by- products that would otherwise react to form new interferences. Electrical signals resulting from the detection of the ions are processed into digital information that is used to indicate the intensity of the ions and subsequently the concentration of the element. In this method, arsenic (isotope mass 75) and gallium (isotope mass 71) or tellurium (isotope mass 126) is measured in urine by ICP-DRC-MS using argon/hydrogen (90%/10%, respectively) as a reaction gas. Urine samples are diluted 1:9 with 2% (v/v) double-distilled nitric acid containing gallium or tellurium for internal standardization.

2. Speciated arsenics (arsenobetaine, arsenocholine, trimethylarsine oxide, monomethylarsonic acid, dimethylarsinic acid, arsenous (III) acid, arsenic (V) acid)

The concentration of speciated arsenics are determined by using high performance liquid chromatography (HPLC) to separate the species coupled to an ICP-DRC-MS to detect the arsenic species. This analytical technique is based on separation by anion-exchange chromatography (IC) followed by detection using quadrupole ICP-MS technology and includes DRC™ technology, which minimizes or eliminates many argon-based polyatomic interferences will require 0.5 mL of urine. Arsenic species column separation is largely achieved due to differences in charge-charge interactions of each negatively-charged arsenic component in the mobile phase with the positively-charged quaternary ammonium groups bound at the column’s solid-liquid interface. Upon exit from the column, the chromatographic eluent goes through a nebulizer where it is converted into an aerosol upon entering the spray chamber.

Carried by a stream of argon gas, a portion of the aerosol is transported through the spray chamber and then through the central channel of the plasma, where it is heated to temperatures of 6000-8000° K. This thermal energy atomizes and ionizes the sample. The ions and the argon enter the mass spectrometer through an interface that separates the ICP, which is operating at atmospheric pressure (approximately 760 torr), from the mass spectrometer, which is operating at approximately 10-5 torr.

The mass spectrometer permits detection of ions at each mass-to- charge ratio in rapid sequence, which allows the determination of individual isotopes of an element. Once inside the mass spectrometer, the ions pass through the ion optics, then through the DRC™, and finally through the mass-analyzing quadrupole before being detected as they strike the surface of the detector. The ion optics uses an electrical field to focus the ion beam into the DRC™. The DRC™ component is pressurized with an appropriate reaction gas and contains a quadrupole. In the DRC™, elimination or reduction of argon-based polyatomic interferences takes place through the interaction of the reaction gas with the interfering polyatomic species in the incoming ion beam. The quadrupole in the DRC™ allows elimination of unwanted reaction by-products that would otherwise react to form new interferences.

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 speciated arsenic were measured in a one-third subsample of persons 6 years and over. Special sample weights(WTSA2YR) 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 2003-2004 laboratory data must be conducted with the key survey design and basic demographic variables. The NHANES 2003-2004 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 2003-2004 data files using the unique survey participant identifier SEQN.

Detection Limits

The detection limits were constant for all of the arsenics in the data set.

Lower detection limits for the total and speciated arsenics
Analyte  LLOD 
Urinary total arsenic 0.6 μg/L
Urinary arsenous acid 1.2 μg/L
Urinary Arsenic acid 1.0 μg/L
Urinary Arsenobetaine 0.4 μg/L
Urinary Arsenocholine 0.6 μg/L
Urinary Dimethylarsonic acid 1.7 μg/L
Urinary Monomethylacrsonic acid 0.9 μg/L
Urinary Trimethylarsine Oxide 1.0 μg/L

Two variables are provided for each of these analytes. The variable named URD___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 URX___ provides the analytic result for that analyte.

Please refer to the Analytic Guidelines for further details on the use of sample weights and other analytic procedures.

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 455771.88304 Range of Values 2673 2673
. Missing 0 2673

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
6 to 768 Range of Values 2586 2586
. Missing 87 2673

URXUAS - Urinary total Arsenic (ug/L)

Variable Name:
URXUAS
SAS Label:
Urinary total Arsenic (ug/L)
English Text:
Urinary total Arsenic (ug/L)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.4 to 1221.2 Range of Values 2557 2557
. Missing 116 2673

URDUASLC - Urinary total Arsenic comment code

Variable Name:
URDUASLC
SAS Label:
Urinary total Arsenic comment code
English Text:
Urinary total Arsenic 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 2529 2529
1 Below lower detection limit 28 2557
. Missing 116 2673

URXUAS3 - Urinary Arsenous acid (ug/L)

Variable Name:
URXUAS3
SAS Label:
Urinary Arsenous acid (ug/L)
English Text:
Urinary Arsenous acid (ug/L)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.8 to 23 Range of Values 2573 2573
. Missing 100 2673

URDUA3LC - Urinary Arsenous acid comment code

Variable Name:
URDUA3LC
SAS Label:
Urinary Arsenous acid comment code
English Text:
Urinary Arsenous acid 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 137 137
1 Below lower detection limit 2436 2573
. Missing 100 2673

URXUAS5 - Urinary Arsenic acid (ug/L)

Variable Name:
URXUAS5
SAS Label:
Urinary Arsenic acid (ug/L)
English Text:
Urinary Arsenic acid (ug/L)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.7 to 8.8 Range of Values 2573 2573
. Missing 100 2673

URDUA5LC - Urinary Arsenic acid comment code

Variable Name:
URDUA5LC
SAS Label:
Urinary Arsenic acid comment code
English Text:
Urinary Arsenic acid 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 167 167
1 Below lower detection limit 2406 2573
. Missing 100 2673

URXUAB - Urinary Arsenobetaine (ug/L)

Variable Name:
URXUAB
SAS Label:
Urinary Arsenobetaine (ug/L)
English Text:
Urinary Arsenobetaine (ug/L)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.3 to 1011.3 Range of Values 2573 2573
. Missing 100 2673

URDUABLC - Urinary Arsenobetaine comment code

Variable Name:
URDUABLC
SAS Label:
Urinary Arsenobetaine comment code
English Text:
Urinary Arsenobetaine 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 1716 1716
1 Below lower detection limit 857 2573
. Missing 100 2673

URXUAC - Urinary Arsenocholine (ug/L)

Variable Name:
URXUAC
SAS Label:
Urinary Arsenocholine (ug/L)
English Text:
Urinary Arsenocholine (ug/L)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.4 to 9.4 Range of Values 2573 2573
. Missing 100 2673

URDUACLC - Urinary Arsenocholine comment code

Variable Name:
URDUACLC
SAS Label:
Urinary Arsenocholine comment code
English Text:
Urinary Arsenocholine 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 41 41
1 Below lower detection limit 2532 2573
. Missing 100 2673

URXUDMA - Urinary Dimethylarsonic acid (ug/L)

Variable Name:
URXUDMA
SAS Label:
Urinary Dimethylarsonic acid (ug/L)
English Text:
Urinary Dimethylarsonic acid (ug/L)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1.2 to 71 Range of Values 2573 2573
. Missing 100 2673

URDUDALC - Urinary Dimethylarsonic acid comment

Variable Name:
URDUDALC
SAS Label:
Urinary Dimethylarsonic acid comment
English Text:
Urinary Dimethylarsonic acid 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 2248 2248
1 Below lower detection limit 325 2573
. Missing 100 2673

URXUMMA - Urinary Monomethylacrsonic acid (ug/L)

Variable Name:
URXUMMA
SAS Label:
Urinary Monomethylacrsonic acid (ug/L)
English Text:
Urinary Monomethylacrsonic acid (ug/L)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.6 to 16 Range of Values 2572 2572
. Missing 101 2673

URDUMMAL - Urinary Monomethylacrsonic acid comment

Variable Name:
URDUMMAL
SAS Label:
Urinary Monomethylacrsonic acid comment
English Text:
Urinary Monomethylacrsonic acid 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 931 931
1 Below lower detection limit 1641 2572
. Missing 101 2673

URXUTM - Urinary Trimethylarsine Oxide (ug/L)

Variable Name:
URXUTM
SAS Label:
Urinary Trimethylarsine Oxide (ug/L)
English Text:
Urinary Trimethylarsine Oxide (ug/L)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.7 to 27 Range of Values 2573 2573
. Missing 100 2673

URDUTMLC - Urinary Trimethylarsine Oxide comment

Variable Name:
URDUTMLC
SAS Label:
Urinary Trimethylarsine Oxide comment
English Text:
Urinary Trimethylarsine Oxide 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 12 12
1 Below lower detection limit 2561 2573
. Missing 100 2673