Component Description
Sulfonylurea herbicides are a group of non-selective herbicides that act by disrupting plant protein synthesis. They have been introduced relatively recently and are widely used, but application rates are relatively low. Potential sources for human exposure include foods grown in treated soil or contaminated water. Urinary measurement of sulfonylurea herbicides can be used to assess human exposure.
Also included are urinary measurements of several organophosphorus pesticides (acephate, methamidophos, dimethoate and its metabolite, omethoate), carbamate pesticide metabolites (carbofuranphenol, isopropoxyphenol), fungicide metabolites (ethylene thiourea, propylene thiourea), herbicides (2,4-dichlorophenoxyacetic acid, 2,4,5-trichorophenoxyacetic acid), and pentachlorophenol. These are a diverse group of chemicals that may have residential and/or agricultural uses, although methamidophos is no longer registered for use in the United States, and carbofuran has restricted use on limited agricultural crops. Human exposure to pesticides may occur through consumption of contaminated food or water, contact with treated surfaces or the pesticide itself, and from inhaling pesticide vapor or fumes.
Acephate (URXAPE), Ethylenethio Urea (URXETU), Methamidaphos (URXMMI), Dimethoate (URXMTO), O-Methoate (URXOMO), and Propylenethio Urea (URXPTU)
Acephate (APE), methamidophos (MMI), O-methoate (OMO), and dimethoate (MTO), are organophosphorus (OP) pesticides. OP pesticides are the most commonly used insecticides in agriculture and the domestic field.
The most widely used fungicides in agriculture are the alkali and metal salts of the alkelenebis-(dithiocarbamate) acids. Ethylenethio urea (ETU) represents the main degradation product of the ethylene bisdithiocarbamates and propylenethio urea (PTU) is the main degradation product of the propylene bisdithiocarbamates. They are foliar applied compounds that control many fungal diseases including early and late blights, leaf spots, rust mildew and scabs in various field crops such as fruits, nuts, cucurbits, vegetables, grapes, and ornamentals.
Bensulfuron methyl (URXBSM), Chlorsulfuron (URXCHS), Ethametsulfuron methyl (URXEMM), Foramsulfuron (URXFRM), Halosulfuron (URXHLS), Mesosulfuron methyl (URXMSM), Metsulfuron methyl (URXMTM), Nicosulfuron (URXNOS), Oxasulfuron (URXOXS), Primisulfuron methyl (URXPIM), Prosulfuron (URXPRO), Rimsulfuron (URXRIM), Sulfometuron methyl (URXSMM), Sulfosulfuron (URXSSF), Thifensulfuron methyl (URXTHF), Triasulfuron (URXTRA), Triflusulfuron methyl (URXTRN)
Because of their increasing use in agricultural applications, a method to measure both occupational and incidental human exposures to Sulfonylurea herbicides was developed.
Carbofuranphenol (URXCBF), Pentachlorophenol (URXPCP), and 2-isopropoxyphenol (URXPPX)
Altogether, these target compounds represent some of the most used pesticides in the United States and give a general, though not total, evaluation of a person’s pesticide exposure.
2,4-D (URX24D), 2,4,5-Trichlorophenoxyacetic acid (URX25T)
In 1999, an estimated 415,000 tons of conventional pesticides were applied in the United States. The most commonly used pesticide for home and garden was the herbicide 2, 4-D with an estimated use of 3000-4000 tons in those applications, giving an average domestic use per capita of ~ 15g /year. During the same year, the most abundantly applied pesticide in U. S. agriculture was atrazine, with application of 35,000 tons. The widespread use of pesticides and the scientific interest in potential adverse health effect of pesticides exposure have increased the demand for fast and robust analytical methods for measuring markers of possible pesticides.
This method assesses human exposure to select pesticide metabolites of non-persistent pesticides. It does not directly test for any disease. This method includes specific organophosphorous insecticide metabolites (5-chloro-1-isopropyl-[3H]-1, 2, 4-triazol-3-one; 2-diethylamino-6-methyl pyrimidin-4-ol; 2-isopropyl-6-methyl-4-pyrimidiol; 3-chloro-4-methyl-hydroxycoumarin; 2-[(dimethoxy-phosphorothioyl) sulfanyl] succinic acid; 3, 5, 6-tricholor-2-pyridinol; 4-nitrophenol, synthetic pyrethroids (3-[(1Z)-2-carboxyprop-1-en-1-yl]-2,2-dimethylcyclopropanecarboxylic acid; 3-phenoxybenzoic acid; 4-fluoro-3-phenoxybenzoic acid; cis-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropane-1-carboxylic acid; trans-3-(2,2-dichlorovinyl) -2,2-dimethyl-cyclopropane-1-carboxylic acid; trans - 3 -(2,2 dibromovinyl) -2,2-dimethyl cyclo propane-1-carboxylic acid), herbicides (acetochlor mercapturate; alachlor mercapturate; atrazine mercapturate; metolachlor mercapturate; 2,4-dichloro-phenoxyacetic acid; 2,4,5-trichlorophenoxyacetic acid), and an insect repellant N, N-diethyl-m-toluamide (DEET).
Eligible Sample
Participants aged 6 years and older who met the subsample requirements.
Description of Laboratory Methodology
Acephate (URXAPE), Ethylenethio Urea (URXETU), Methamidaphos(URXMMI), Dimethoate (URXMTO), O-Methoate (URXOMO), and Propylenethio Urea (URXPTU)
The general sample preparation included lyophilization of the urine samples followed by extraction with dichloromethane. The analytical separation was performed by high-performance liquid chromatography (HPLC), and detection by a triple quadrupole mass spectrometer with and APCI source in positive ion mode using multiple reactions monitoring (MRM) and tandem mass spectrometry (MS/MS) analysis. Two different Thermo-Finnigan triple quadrupole mass spectrometers, a TSQ 7000 and a TSQ Quantum Ultra, were used.
Bensulfuron methyl (URXBSM), Chlorsulfuron (URXCHS), Ethametsulfuron methyl (URXEMM), Foramsulfuron (URXFRM), Halosulfuron (URXHLS), Mesosulfuron methyl (URXMSM), Metsulfuron methyl (URXMTM), Nicosulfuron (URXNOS), Oxasulfuron (URXOXS), Primisulfuron methyl (URXPIM), Prosulfuron (URXPRO), Rimsulfuron (URXRIM), Sulfometuron methyl (URXSMM), Sulfosulfuron (URXSSF), Thifensulfuron methyl (URXTHF), Triasulfuron (URXTRA), Triflusulfuron methyl (URXTRN)
A method for measuring 17 sulfonylurea (SU) herbicides in human urine was developed. Urine samples were extracted using solid phase extraction (SPE), pre-concentrated, and analyzed by high-performance liquid chromatography–tandem mass spectrometry using turbo-ionspray atmospheric pressure ionization. Carbon 13-labeled ethametsulfuron methyl was used as an internal standard. Chromatographic retention times were under 7 minutes. Total throughput was estimated as >100 samples per day. The limits of detection (LOD) ranged from 0.05 µg/L to 0.10 µg/L with an average LOD of 0.06 µg/L. Average total relative standard deviations were 17%, 12% and 8% at 0.1 µg/L, 3.0 µg/L and 10 µg/L, respectively. Average extraction efficiencies of the SPE cartridges were 87% and 86% at 2.5 µg/L and 25 µg/L, respectively. Chemical degradation in acetonitrile and urine was monitored over 250 days. Estimated days for 10% and 50% degradation in urine and acetonitrile ranged from 0.7 days to >318 days.
Carbofuranphenol (URXCBF), Pentachlorophenol (URXPCP), and 2-isopropoxyphenol (URXPPX)
A method to measure 12 urinary phenolic metabolites of pesticides or related chemicals has developed. The target chemicals for our method are 2-isopropoxyphenol; 2,4-dichlorophenol; 2,5-dichlorophenol; carbofuranphenol; 2,4,5-trichlorophenol; 2,4,6-trichlorophenol; 3,5,6-trichloro-2-pyridinol; para-nitrophenol, ortho-phenylphenol, pentachlorophenol, 1-naphthol and 2-naphthol. The sample preparation involves enzyme hydrolysis, isolation of the target chemicals using solid phase extraction cartridges, a phase-transfer catalyzed derivatization, cleanup using sorbent-immobilized liquid /liquid extraction cartridges, and concentration of the sample. Derivatized samples are analyzed by capillary gas chromatography-tandem mass spectroscopy using isotope dilution calibration for quantification. The limits of detection are in the mid ng/L range and the average coefficient of variation was below 15% for most of the analytes. Using our method, we measured concentrations of the target chemicals in urine samples from the general population.
2,4-D (URX24D), 2,4,5-Trichlorophenoxyacetic acid (URX25T)
The analytes are extracted and concentrated from the urine matrix using solid phase extraction cartridges, separated through high pressure liquid chromatography, and analyzed on a triple quadrupole mass spectrometer.
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 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 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 Westgard 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 Westgard (1981)).
Analytic Notes
The list of chemicals in the following table have been withdrawn from the 2003-2004 Urinary Current Use Pesticide file (L26UPP_C) due to unacceptable measurement variance at or near the limit of detection.
Chemical name
Atrazine mercapturate
Atrazine
Desethyl atrazine mercapturate
Diaminochloroatrazine
Desethyl atrazine
Desisopropyl atrazine
Acetochlor mercapture
Alachlor mercapturate
cis-dibromovinyl-dimethyl cyclopropane carboxylic acid
cis-dichlorovinyl-dimethylcyclopropane carboxylic acid
Chloro-dihydro-isopropyl-triazol/one
cis-dimethylvinyl-dimethylcyclo-propane carboxylic acid
Chloro-hydroxy-methyl-chromen-ol/one
DEET
Diethylaminomethylpyrimidine-ol/one
Fluoro-phenoxybenzoic acid
Malathion diacid
Metolachlor mercapturate
3-phenoxybenzoic acid
Paranitrophenol
trans-dichlorovinyl-dimethylcylopropane carboxylic acid
Subsample weights
Measures of urinary diakyl phosphate metabolites 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 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
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.