Organochlorine pesticides are a diverse group of synthetic chemicals that persist in the environment and tend to bioaccumulate. Most of these chemicals have been banned from use in the U.S. Assessment of exposure to persistent organochlorine pesticides in a representative sample of the U.S. population is needed to determine current prevalence and level of exposure and the potential for human health effects from exposure to these chemicals.
Examined participants aged 12 years and older from a one-third sample were eligible.
Serum samples from NHANES 2009-2010 were stored frozen before analysis. Eight organochlorine pesticides and metabolites were measured in serum through the use of automated liquid/liquid extraction and subsequent sample clean-up. Final determination of target analytes was performed by isotope dilution gas chromatography high-resolution mass spectrometry GC/IDHRMS. The analytical method is described in Jones et al, 2012, which is a modification of the method described by Sjodin et al., 2004.
Refer to the Laboratory Method Files for a detailed description of the laboratory methods used.
There were no changes to the lab method, lab equipment, or lab site for this component in the NHANES 2009-2010 cycle.
Polybrominated diphenyl ethers (PBDEs), Polybrominated Biphenyls (PBBs), Polychlorinated biphenyls and Persistent Pesticides (September 2017)
Serum samples were 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 Procedure Manual (LPM). Vials are stored under appropriate frozen (-30oC) conditions until they are shipped to the 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.
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 quality-control 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 quality control 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 Environmental Health Laboratory Sciences’ quality control and quality assurance performance criteria for accuracy and precision, similar to the Westgard rules (Caudill, et al. 2008).
The data were reviewed. Incomplete data or improbable values were sent to the performing laboratory for confirmation.
Refer to the 2009-2010 Laboratory Data Overview for general information on NHANES laboratory data.
Subsample Weights
Organochlorine pesticides were measured in a one-third subsample of participants 12 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.
Samples were pooled in groups of 8 samples per pool within 40 demographic groups. The analysis of NHANES 2009-2010 pooled-sample data must be conducted with the basic demographic variables provided in this data file. This pooled-sample data file cannot be linked to other NHANES 2009-2010 data. Because each sample person does not have an equal probability of selection, sample weighting is needed to produce correct population estimates of means, percentiles, and other descriptive statistics.
The pooled-sample weights required to produce estimates from these data are included in this data file. The analysis of pooled-samples from survey data is a relatively new field of study, and there is currently no established method to produce design effect adjusted variance estimates for these pooled results. These data cannot be analyzed using software designed for complex surveys because design features are not available.
Rationale and Methods Used to Create Pooled Results
The Centers for Disease Control and Prevention (CDC) provides an ongoing assessment of the US population's exposure to environmental chemicals by using biomonitoring in conjunction with CDC's National Health and Nutrition Examination Survey (NHANES). Characterizing the distributions of concentrations of environmental compounds or their metabolites in the US population is a primary objective of CDC's biomonitoring program. Historically, this characterization has been based on individual measurements of these compounds in body fluid or tissue from representative samples of the population. Pooling samples allows for larger sample volumes which can result in lower limits of detection and reduces the number of measurements and costs. In NHANES 2009-2010, a weighted pooled-sample design was implemented to facilitate pooling samples before making analytical measurements. Table 1 lists the International Union of Pure and Applied Chemistry (IUPAC) names, common abbreviation, and NHANES variable name for the analytes included in this data file.
Pools were prepared from serum collected from a random one-third subset of the NHANES 2009-2010 participants aged 12 years and older. Samples were pooled based on gender, race and Hispanic origin, and age. To implement the pooled-sample design, each participant sample was identified as belonging to one of 40 demographic groups based on race and Hispanic origin (Mexican American: MA, Other Hispanic: OH, non-Hispanic white: NHW, non-Hispanic black: NHB, Other race including multiracial: OTHER), gender (Male, Female), and age group (12-19, 20-39, 40-59, and 60+ years of age and older). Eight (8) samples were included in each pool. The number of pools created for each of the 40 demographic groups varied depending on the total number of individual samples available in a demographic group. The one-third subset of NHANES 2009-2010 represents 2524 individual samples, but because the pooled-sample design requires that all samples be of sufficient volume and that there be the same number of samples in each pool, 2322 samples were available to create 301 pools with 8 samples per pool (Exceptions are in Table 2). The variable SAMPLEID denotes the identification number for each pool and ranges from 1 through 303, excluding the numbers 265 and 266. Please refer to the Pooled-Sample Technical Support file (POOLTF_F) for detailed information on individual participants included in each pool.
In order to incorporate sample weighting into the pooled-sample design it was necessary to use a different volume of material from each sample contributing to a pool. The volume chosen for each sample in a pool was based on the ratio of its sampling weight to the sum of the sampling weights of all samples in the pool. To physically accomplish the pooling in the laboratory required that the ratio of the largest to the smallest sampling weight of samples in the same pool be no larger than about 4 or 5. The individual samples were sorted/stratified by sampling weight within each of the 40 demographic groups and pools were formed using samples with sampling weights adjacent to one another in the sorted list. The number of samples in the one-third subset, number of samples available, the number of these samples that were usable, and the number of pools formed in each demographic group are presented in Table 2. Once the pools were created, summed sampling weights were further adjusted to account for the unused samples. These adjusted summed sampling weights are represented by the variable named WTSMSMPA.
Detection Limits
In the dataset, the whole-weight detection limit (pg/g serum) is a variable and dependent on the available sample size; however, the variation in sample size was low. Lipid adjusted detection limits are variable (ng/g lipid) due to differences of the lipid levels measured in individual pools/specimens. In cases where the result was below the limit of detection, the value for that variable is the detection limit divided by the square root of 2.
Table 1. NHANES Variable name, common abbreviation and International Union of Pure and Applied Chemistry (IUPAC) name for each analyte reported and maximum limit of detection (MLOD).
Variable Name | Common Abbrev. | IUPAC Name | MLODa (pg/g serum) | MLODa (ng/g lipid) |
---|---|---|---|---|
LBCHCB | HCB | Hexachlorobenzene | 13.4 | 3.11 |
LBCBHC | B-HCCH | BETA-Hexachlorocyclohexane | 9.2 | 2.19 |
LBCGHC | G-HCCH | GAMA-Hexachlorocyclohexane (Lindane) | 9.2 | 2.19 |
LBCOXY | OXYCHLOR | Oxychlordane | 60.1 | 14.14 |
LBCTNA | T-NONA | Trans-Nonachlor | 9.2 | 2.19 |
LBCPDE | PP-DDE | 2,2-Bis(4-chlorophenyl)-1,1-dichloroethene | 15.6 | 3.68 |
LBCPDT | PP-DDT | 2,2-Bis(4-chlorophenyl-1,1,1-trichloroethan | 9.2 | 2.19 |
LBCMIR | MIREX | Mirex | 9.2 | 2.19 |
aThe values given in the tables are the maximum limit of detection (MLOD) divided by the square root of 2 and are expressed as pg/g serum and ng/g lipid.
Table 2. Number of subjects in the one-third subsample, number of individual serum samples available, number of usable samples, and number of pools formed from NHANES 2009-2010 participants per demographic group.
Race/ Ethnicity |
Gender
|
Number of subjects in the one-third subsample/ Number of Samples Available/Number of Usable Samples (Number of Pools) |
|||
12–19 years (RIDAGEYR=1)1 |
20–39 years (RIDAGEYR=2) |
40–59 years (RIDAGEYR=3) |
60+ years (RIDAGEYR=4) |
||
Mexican American (RIDRETH1=1) 1 |
Male (RIAGENDR=1) 1 |
65/61/602 (8) |
67/65/64 (8) |
70/65/64 (8) |
43/40/40 (5) |
Female (RIAGENDR=2) |
57/52/523 (7) |
80/76/764 (10) |
73/72/72 (9) |
51/49/48 (6) |
|
Other Hispanics (RIDRETH1=2) |
Male (RIAGENDR=1) |
22/20/205 (3) |
35/34/346 (5) |
40/39/397 (5) |
26/24/24 (3) |
Female (RIAGENDR=2) |
22/20/205 (3) |
38/33/32 (4) |
39/34/348 (5) |
38/35/359 (5) |
|
Non-Hispanic White (RIDRETH1=3) |
Male (RIAGENDR=1) |
91/79/7910 (10) |
139/135/13511 (17) |
146/142/136 (17) |
182/175/168 (21) |
Female (RIAGENDR=2) |
76/65/6312 (8) |
164/151/15013 (19) |
149/138/136 (17) |
188/178/176 (22) |
|
Non-Hispanic Black (RIDRETH1=4) |
Male (RIAGENDR=1) |
45/43/4314 (6) |
56/52/523 (7) |
60/54/5415 (7) |
72/67/6716 (9) |
Female (RIAGENDR=2) |
53/48/48 (6) |
63/57/56 (7) |
60/53/5317 (7) |
58/52/523 (7) |
|
Other Race including Multiracial (RIDRETH1=5) |
Male (RIAGENDR=1) |
13/11/1118 (2) |
21/19/1819 (3) |
18/18/16 (2) |
16/15/1520 (2) |
Female (RIAGENDR=2) |
18/17/16 (2) |
31/30/3021 (4) |
23/21/2122 (3) |
16/15/1323 (2) |
Methodological approaches for analysis
There are a few pooled-sample methodological publications, which address approaches related to the following topics:
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 to 303 | Range of Values | 301 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 | Mexican American | 61 | 61 | |
2 | Other Hispanic | 33 | 94 | |
3 | Non-Hispanic White | 131 | 225 | |
4 | Non-Hispanic Black | 56 | 281 | |
5 | Other Race, Including Multiracial | 20 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 | 12-19 years | 55 | 55 | |
2 | 20-39 years | 84 | 139 | |
3 | 40-59 years | 80 | 219 | |
4 | 60+ years | 82 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1 | Male | 148 | 148 | |
2 | Female | 153 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
2 to 8 | Range of Values | 301 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
49070.542891 to 2980185.9468 | Range of Values | 301 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
3.465 to 4801 | Range of Values | 295 | 295 | |
. | Missing | 6 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0.5657 to 899.5 | Range of Values | 295 | 295 | |
. | Missing | 6 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0 | At or above the detection limit | 260 | 260 | |
1 | Below lower detection limit | 35 | 295 | |
. | Missing | 6 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
3.465 to 9.192 | Range of Values | 301 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0.3748 to 2.192 | Range of Values | 301 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0 | At or above the detection limit | 1 | 1 | |
1 | Below lower detection limit | 300 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
20.16 to 1351 | Range of Values | 301 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
4.573 to 192.4 | Range of Values | 301 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0 | At or above the detection limit | 301 | 301 | |
1 | Below lower detection limit | 0 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
3.465 to 224.1 | Range of Values | 301 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0.495 to 40.08 | Range of Values | 301 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0 | At or above the detection limit | 198 | 198 | |
1 | Below lower detection limit | 103 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
22.63 to 303.5 | Range of Values | 296 | 296 | |
. | Missing | 5 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
3.394 to 57.13 | Range of Values | 296 | 296 | |
. | Missing | 5 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0 | At or above the detection limit | 176 | 176 | |
1 | Below lower detection limit | 120 | 296 | |
. | Missing | 5 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
131.9 to 54740 | Range of Values | 299 | 299 | |
. | Missing | 2 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
26.21 to 7134 | Range of Values | 299 | 299 | |
. | Missing | 2 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0 | At or above the detection limit | 299 | 299 | |
1 | Below lower detection limit | 0 | 299 | |
. | Missing | 2 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
3.465 to 4437 | Range of Values | 301 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0.7071 to 578.2 | Range of Values | 301 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0 | At or above the detection limit | 290 | 290 | |
1 | Below lower detection limit | 11 | 301 | |
. | Missing | 0 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
6.787 to 653.1 | Range of Values | 299 | 299 | |
. | Missing | 2 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
1.556 to 112.5 | Range of Values | 299 | 299 | |
. | Missing | 2 | 301 |
Code or Value | Value Description | Count | Cumulative | Skip to Item |
---|---|---|---|---|
0 | At or above the detection limit | 298 | 298 | |
1 | Below lower detection limit | 1 | 299 | |
. | Missing | 2 | 301 |