• 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

2007-2008 Data Documentation, Codebook, and Frequencies

Pesticides - Carbamates & Organophosphorus Metabolites - Urine (CARB_E)

Data File: CARB_E.xpt

First Published: June 2014

Last Revised: NA

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 instructions on specimen collection and processing are discussed in the NHANES Laboratory Procedures Manual (LPM). Vials are stored under appropriate frozen (–30°C) conditions until they are shipped to National Center for Environmental Health for testing.

The NHANES quality assurance and quality control (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 (Westgard et al, 1981) 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 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 Sciences’ quality control and quality assurance performance criteria for accuracy and precision, similar to the Westgard rules.

 

Analytic Notes

Refer to the NHANES 2011–2012 Lab Data Overview for general information on NHANES laboratory data.

Subsample weights 
Uurinary 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.

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

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 data files using the unique survey participant identifier SEQN.

Detection Limits
The detection limits were constant for all of the analytes in the data set. 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. For analytes with analytic results below the lower limit of detection (i.e., URD___LC=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 lower limits of detection (LLOD, in ng/mL) for these analytes are:

Analyte	Item ID	LLOD
Acephate	URXAPE	0.27
Ethylene thiourea	URXETU	0.21
Methamidophos	URXMMI	0.41
Dimethoate	URXMTO	0.10
Omethoate	URXOMO	0.10
Propylene thiourea	URXPTU	0.36

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

 

Codebook and Frequencies