• Component Description
• Eligible Sample
• Description of Laboratory Methodology
• Laboratory Quality Assurance and Monitoring
• Analytic Notes
• Codebook
  • SEQN - Respondent sequence number
  • WTSC2YR - Environmental C 2 year weights
  • URXAPE - Acephate (ug/L)
  • URDAPELC - Acephate comment code
  • URXETU - Ethylenethio urea (ug/L)
  • URDETULC - Ethylenethio urea comment code
  • URXMMI - Methamidaphos (ug/L)
  • URDMMILC - Methamidaphos comment code
  • URXMTO - Dimethoate (ug/L)
  • URDMTOLC - Dimethoate comment code
  • URXOMO - O-methoate (ug/L)
  • URDOMOLC - O-methoate comment code
  • URXPTU - Propylenethio urea (ug/L)
  • URDPTULC - Propylenethio urea comment code
  • URXUCR - Creatinine, urine (mg/dL)

National Health and Nutrition Examination Survey

2005-2006 Data Documentation, Codebook, and Frequencies

Pesticides - Carbamates & Organophosphorus Metabolites - Urine (CARB_D)

Data File: CARB_D.xpt

First Published: February 2013

Last Revised: April 2013

Component Description

Ethylene thiourea (ETU) is a metabolite and environmental breakdown product of several fungicides in the dithiocarbamates class of chemicals, of which zineb, maneb, metiram, and mancozeb are examples. Propylenethiourea (PTU) is the metabolite and environmental breakdown product of propineb. These fungicides can be applied to fruits, vegetables, field crops, and ornamental plants, but they are not registered for residential use. ETU and related chemicals have numerous industrial uses and have also been used as scavengers in waste water treatment. ETU and PTU do not bioaccumulate and are rapidly eliminated in urine following human exposure.

Two organophosphorus insecticides and their metabolites have been measured: dimethoate and its metabolite, omethoate; acephate; and methamidophos, which is also a metabolite of acephate. Dimethoate and methamidophos are not registered for use in the U.S. Acephate has been used to control insects on field and food crops, on ornamental plants, sods and turf, and in food handling establishments and around commercial and residential buildings. Acephate and its metabolite, methamidophos, do not bioaccumulate and they break down in soils after several days. Measuring these pesticides and the metabolites in urine are important to evaluate human exposure and potential for health effects.

Eligible Sample

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

 

Description of Laboratory Methodology

This method is used for determining concentrations of specific organophosphorous
and carbamate metabolites, in particular, AP, MMP, Omet, Dmet, ETU and PTU
from a urine matrix. The general sample preparation includes lyophilization of the
urine followed by extraction with dichloromethane using a 96-well plate automated sample handler. The analytical separation is performed by high-performance liquid chromatography, and detection by a triple quadrupole mass spectrometer with APCI source in positive ion mode using MS/MS. Isotopically labeled internal standards were used for three of the analytes.

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 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 Amendments 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 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.

NCEH developed and distributed a quality control protocol for all the laboratories which outlined the Westgaard rules used when running NHANES specimens. Any problems encountered during shipping or receipt of specimens, instrument calibration, reagents, and any special considerations are submitted to NCHS and Westat. Summary statistics for each control pool, QC graphs, are reviewed by NCHS 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 Sciences’ quality control and quality assurance performance criteria for accuracy and precision (similar to specifications outlined by Westgaard (1981)).

 

Analytic Notes

Subsample weights 
Measures of urinary carbamate and phosphorus pesticides 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 Demographic file contains: Status Variables providing core information on the survey participant including examination status, Recoded Demographic Variables including age, gender, race etc., and Interview and Examination Sample Weight Variables and Survey Design Variables. The recommended procedure for variance estimation requires use of stratum and PSU variables (SDMVSTRA and SDMVPSU, respectively), which are included in the demographic data file for each data release. The Questionnaire Data Files contain socio-economic data, health indicators, and other related information collected during household interviews. The Phlebotomy Examination file includes auxiliary information on duration of fasting, the time of day of the venipuncture, and the conditions precluding venipuncture. The Demographic, Questionnaire and Phlebotomy Examination files may be linked to the laboratory data file using the unique survey participant identifier SEQN.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.

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
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.

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.

Codebook and Frequencies