• Component Description
• Eligible Sample
• Description of Laboratory Methodology
• Laboratory Method Files
• Laboratory Quality Assurance and Monitoring
• Data Processing and Editing
• Analytic Notes
• References
• Codebook
  • SEQN - Respondent sequence number
  • WTSC2YR - Environmental Subsample C Weights
  • URX24D - 2,4-D (ug/L)
  • URD24DLC - 2,4-D Comment Code
  • URXCPM - 3,5,6-trichloropyridinol (ug/L)
  • URDCPMLC - 3,5,6-trichloropyridinol Comment Code
  • URX4FP - 4-fluoro-3-phenoxy-benzoic acid (ug/L)
  • URD4FPLC - 4-fluoro-3-phenoxy-benzoic acid Cmt Code
  • URXOPM - 3-phenoxybenzoic acid (ug/L)
  • URDOPMLC - 3-phenoxybenzoic acid Comment Code
  • URXOXY - Oxypyrimidine (ug/L)
  • URDOXYLC - Oxypyrimidine Comment Code
  • URXPAR - para-Nitrophenol (ug/L)
  • URDPARLC - para-Nitrophenol Comment Code
  • URXTCC - Dichlorovnl-dimeth prop carboacid (ug/L)
  • URDTCCLC - Dichlorovnl-dimeth prop carboacid Code

National Health and Nutrition Examination Survey

2013-2014 Data Documentation, Codebook, and Frequencies

Pyrethroids, Herbicides, & Organophosphorus Metabolites - Urine (UPHOPM_H)

Data File: UPHOPM_H.xpt

First Published: May 2020

Last Revised: NA

Component Description

In 2007, an estimated 857 million pounds of conventional pesticides were used in the United States (EPA, 2020). Chlorpyrifos was the insecticide used the most in the agricultural market sector with 7-9 million pounds applied. 2,4-D was the most used herbicide in the home and garden sector and the commercial sector, and it was the second most used herbicide in the agricultural sector. Malathion was the most used insecticide in the commercial sector and the second most used insecticide in the home and garden sector. Pyrethroids were the most used insecticides in the home and garden sector. In 2007, the United States used 22% of all pesticides applied throughout the world. The widespread use of pesticides and the scientific interest in potential adverse health effects of pesticides exposure have increased the demand for fast and robust analytical methods for measuring biomarkers of pesticides.

This component measures urinary concentrations of three organophosphorus insecticide metabolites: 3,5,6-trichloropyridinol, 2-isopropyl-6-methyl-4-pyrimidiol and para-nitrophenol; three synthetic pyrethroid metabolites: 3-phenoxybenzoic acid, 4-fluoro-3-phenoxybenzoic acid, and trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropane-1-carboxylic acid; and one herbicide: 2,4-dichlorophenoxyacetic acid.

Eligible Sample

Examined participants aged 6 years and older were eligible.

Description of Laboratory Methodology

Target analytes are extracted and concentrated from the urine matrix using an automated solid phase extraction system. Selective separation of the analytes is achieved using high-performance liquid chromatography with a gradient elution program. Sensitive detection of the analytes is performed by a triple quadrupole mass spectrometer with a heated electrospray ionization source. Analytes are identified using the specific m/z ion transition, the retention time and the ion ratio of the quantification and confirmation m/z ion transitions. Isotopically labeled internal standards are used for precise and accurate quantification. The approach followed is a modification of previous methodology (Beeson et al. 1999; Olsson et al. 2004).

Refer to the Laboratory Method Files section for a detailed description of the laboratory methods used.

There were no changes to the lab method, lab equipment, and lab site for this component in the NHANES 2013-2014 cycle.

Laboratory Method Files

UPHOPM Laboratory Procedure Manual (May 2020)

Laboratory Quality Assurance and Monitoring

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

Detailed instructions on specimen collection and processing are discussed in the NHANES Laboratory Procedures Manual (LPM). Vials were stored under appropriate frozen (–30°C) conditions until they were shipped to Division of Laboratory Sciences for testing.

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 LPM.

Mobile Examination Centers (MECs)

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

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 during “dry run” sessions. In addition, contract laboratories randomly perform repeat testing on 2% of all specimens.

NCHS developed and distributed a QC protocol for all CDC and contract laboratories, which outlined the use of Westgard rules (Westgard, et al., 1981) 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 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 Services’ QA/QC performance criteria for accuracy and precision, similar to the Westgard 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

Refer to the 2013-2014 Laboratory Data Overview for general information on NHANES laboratory data.

There are over 800 laboratory tests performed on NHANES participants. However, not all participants provided biospecimens or enough volume for all the tests to be performed. The specimen availability can also vary by age or other population characteristics. Analysts should evaluate the extent of missing data in the dataset related to the outcome of interest as well as any predictor variables used in the analyses to determine whether additional re-weighting for item non-response is necessary.

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.

Subsample Weights

Pyrethroids, Herbicides, & Organophosphorus Metabolites were measured in a one-third subsample of participants 6 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.

Demographic and Other Related Variables

The analysis of NHANES laboratory data must be conducted using the appropriate survey design and demographic variables. The NHANES 2013-2014 Demographics File contains demographic data, health indicators, and other related information collected during household interviews as well as the 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. 

This laboratory data file can be linked to the other NHANES data files using the unique survey participant identifier (i.e., SEQN).

The variable URXUCR (urine creatinine) will not be reported in this file. URXUCR can be found in the data file titled “Albumin & Creatinine – Urine”.

Detection Limits

The detection limit was constant for the analyte in the data set. Two variables are provided for this analyte. The variable name ending in “LC” (ex., URD24DLC) 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 the analyte with analytic results below the lower limit of detection (URD24DLC=1), an imputed fill value was placed in the analyte results field. This value is the lower limit of detection divided by square root of 2 (LLOD/sqrt [2]). The variable prefixed URX (ex., URX24D) provides the analytic result for that analyte.

The lower limit of detection (LLOD, in ug/L) for Pyrethroids, Herbicides, & Organophosphorus Metabolites:

References

• "About Pesticides." EPA. Environmental Protection Agency, April 14, 2020. http://www.epa.gov/pesticides/about/
• Beeson M.D., Driskell W.J., Barr D.B.. Isotope Dilution High-Performance Liquid Chromatography/Tandem Mass Spectrometry Method for Quantifying Urinary Metabolites of Atrazine, Malathion, and 2,4-Dichlorophenoxyacetic Acid. Anal. Chem., 71:3526-3530, 1999.
• Caudill, S.P., Schleicher, R.L., Pirkle, J.L. Multi-rule quality control for the age-related eye disease study. Statist. Med. (2008) 27(20):4094-40106.
• Olsson A. O., Baker S. E., Nguyen J. V., Romanoff L. C., Udunka S. O., Walker R. D., Flemmen K. L., and Barr D. B.. A Liquid Chromatography-Tandem Mass Spectrometry Multiresidue Method for Quantification of Specific Metabolites of Organophosphorus Pesticides, synthetic Pyrethroids, selected Herbicides, and DEET in Human Urine. Anal. Chem., 76:2453-2461, 2004.
• Westgard J.O., Barry P.L., Hunt M.R., Groth T. A multi-rule Shewhart chart for quality control in clinical chemistry. Clin Chem (1981) 27:493-501.

Codebook and Frequencies