Table of Contents

Component Description

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.

Eligible Sample

A one-third sample of survey participants aged 12 years and older agreeing to a venipuncture.

Description of Laboratory Methodology

Serum samples from NHANES 2007-2008 were stored frozen before analysis. Nine 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 and Barr et al., 2003. Reported results met the Division of Laboratory Sciences’ quality control and quality assurance performance criteria for accuracy and precision (similar to specifications outlined by Westgard (1981).

Data Processing and Editing

Read the General Documentation on Laboratory Data file for detailed data processing and editing protocols.

The analytical methods are described in the Description of the Laboratory Methodology section.

Detection Limits

In the dataset, the whole weight detection limit (ng/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.

Laboratory Quality Assurance and Monitoring

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 Laboratory/Medical Technologists Procedures Manual (LPM).

Read the General Documentation on Laboratory Data  file for detailed QA/QC protocols.

 The analytical methods are described in the Description of the Laboratory Methodology section.

Analytic Notes

Rationale and Methods used to Create Pooled Results

The National 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 2007-2008, a weighted pooled-sample design was implemented to facilitate pooling samples before making analytical measurements.  Table 1 lists the IUPAC (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 2007–2008 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 32 demographic groups based on race and Hispanic origin (non-Hispanic white: NHW, non-Hispanic black: NHB, Mexican American: MA,: not non-Hispanic black, non-Hispanic white or Mexican-American: OTHER), gender (Male, Female), and age group (12-19, 20-39, 40-59, and 60+ years of age and older The number of pools created for each of the 32 demographic groups varied depending on the total number of individual samples available in a demographic group. The one-third subset of NHANES 2007-2008 represents 2282 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, only 2070 samples were available to create 264 pools with 8 samples per pool (Exceptions are in Table 2).

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 32 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.

Table 1. NHANES Variable Name, Common Abbreviation and IUPAC Name for each analyte reported
NHANES Variable Name Common Abbreviation IUPAC Name
LBCHCB HCB Hexachlorobenzene
LBCBHC B-HCCH beta-Hexachlorocyclohexane
LBCGHC G-HCCH gamma-Hexachlorocyclohexane
LBCOXY OXYCHLOR Oxychlordane
LBCTNA T-NONA trans-Nonachlor
LBCPDE PP-DDE p,p'-Dichlorodiphenyldichloroethylene (p,p'-DDE)
LBCPDT PP-DDT p,p'-Dichlorodiphenyltrichloroethane (p,p'-DDT)
LBCMIR MIREX Mirex

Table 2.  Number of subjects per demographic group in the NHANES 2007–2008 one-third subsample, number of individual serum samples available, number of usable samples, and number of pools formed from usable samples.

serum samples available

Pooled-Sample weights

The original pooled-sample weight created for this file released in July 2013 did not accurately take into account the new sample design for this NHANES survey cycle and it was not correctly stratified to the U.S. population total. This new file contains the corrected sample weight (WTSMSMPA). The corrected sample weight was created so that analyses using race and Hispanic origin would be comparable to the three groups used in NHANES 2005-2006 (non-Hispanic white, non-Hispanic black and Mexican-American). Therefore, analyses of the data for ”Total Hispanics” is not appropriate. No changes or corrections were made to the lab analyte data in this new release. Any analyses of the data using the old public use data file should be repeated using the corrected sample weight on this new file.

PBDEs and PBB-153 were measured in a one third subsample of persons 12 years and over, and samples were pooled in groups of 8 samples per pool within 32 demographic groups. The analysis of NHANES 2007-2008 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 2007-2008 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 variance estimates for these pooled results.   These data cannot be analyzed using software designed for complex surveys because design features are not available. 

Methodological Issues for Analysis

There are a few pooled-sample methodological publications which address issues related to the following topics (See References.)

• Variance estimation and bias correction when pooling samples from log-normally distributed populations (Caudill, 2010a; Caudill, 2010b; Caudill et al., 2007);
• Models that incorporate measurement error when analyzing pooled-samples from normally or log-normally distributed populations (Caudill, 2010a);
• Incorporation of sample weighting into a pooled-sample design (Caudill, 2012; Caudill, 2010a);
• Estimation of standard errors and confidence limits for point estimates from pooled-samples (Caudill, 2012; Caudill, 2010a).

References

Codebook and Frequencies

SAMPLEID - Pool identification number

Variable Name:
SAMPLEID
SAS Label:
Pool identification number
English Text:
Pool identification number
Target:
Both males and females 12 YEARS - 150 YEARS

RIAGENDR - Gender

Variable Name:
RIAGENDR
SAS Label:
Gender
English Text:
Gender
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Male 132 132
2 Female 132 264
. Missing 0 264

ETHNICTY - Ethnicity - Recode

Variable Name:
ETHNICTY
SAS Label:
Ethnicity - Recode
English Text:
Ethnicity - Recode
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Non-Hispanic White 118 118
2 Non-Hispanic Black 54 172
3 Mexican American 50 222
4 Other 42 264
. Missing 0 264

RIDAGGRP - Age group

Variable Name:
RIDAGGRP
SAS Label:
Age group
English Text:
Age group
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 12-19 years 42 42
2 20-39 years 72 114
3 40-59 years 71 185
4 60+ years 79 264
. Missing 0 264

RIANSMP - Number of samples in a pool

Variable Name:
RIANSMP
SAS Label:
Number of samples in a pool
English Text:
Number of samples in a pool
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3 to 8 Range of Values 264 264
. Missing 0 264

WTSMSMPA - Adjust sum sampling weights in same pool

Variable Name:
WTSMSMPA
SAS Label:
Adjust sum sampling weights in same pool
English Text:
Adjust sum sampling weights in same pool
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
92401.04944 to 3363512.5108 Range of Values 264 264
. Missing 0 264

LBCBHC - Beta-hexachlorocyclohexane (ng/g)

Variable Name:
LBCBHC
SAS Label:
Beta-hexachlorocyclohexane (ng/g)
English Text:
Beta-hexachlorocyclohexane (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.0044 to 5.2617 Range of Values 264 264
. Missing 0 264

LBCBHCLA - B-hexachlorocyclohexane Lipid Adj (ng/g)

Variable Name:
LBCBHCLA
SAS Label:
B-hexachlorocyclohexane Lipid Adj (ng/g)
English Text:
B-hexachlorocyclohexane Lipid Adj (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.6 to 707 Range of Values 264 264
. Missing 0 264

LBDBHCLC - Beta-hexachlorocyclohexane comment code

Variable Name:
LBDBHCLC
SAS Label:
Beta-hexachlorocyclohexane comment code
English Text:
Beta-hexachlorocyclohexane comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 182 182
1 Below lower detection limit 82 264
. Missing 0 264

LBCGHC - Gamma-hexachlorocyclohexane (ng/g)

Variable Name:
LBCGHC
SAS Label:
Gamma-hexachlorocyclohexane (ng/g)
English Text:
Gamma-hexachlorocyclohexane (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.0043 to 0.0045 Range of Values 264 264
. Missing 0 264

LBCGHCLA - G-hexachlorocyclohexane Lipid Adj (ng/g)

Variable Name:
LBCGHCLA
SAS Label:
G-hexachlorocyclohexane Lipid Adj (ng/g)
English Text:
G-hexachlorocyclohexane Lipid Adj (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.5 to 1 Range of Values 264 264
. Missing 0 264

LBDGHCLC - Gamma-hexachlorocyclohexane comment code

Variable Name:
LBDGHCLC
SAS Label:
Gamma-hexachlorocyclohexane comment code
English Text:
Gamma-hexachlorocyclohexane comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 0 0
1 Below lower detection limit 264 264
. Missing 0 264

LBCHCB - Hexachlorobenzene (ng/g)

Variable Name:
LBCHCB
SAS Label:
Hexachlorobenzene (ng/g)
English Text:
Hexachlorobenzene (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.0274 to 0.4035 Range of Values 264 264
. Missing 0 264

LBCHCBLA - Hexachlorobenzene Lipid Adj (ng/g)

Variable Name:
LBCHCBLA
SAS Label:
Hexachlorobenzene Lipid Adj (ng/g)
English Text:
Hexachlorobenzene Lipid Adj (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
5.5 to 57.1 Range of Values 264 264
. Missing 0 264

LBDHCBLC - Hexachlorobenzene comment code

Variable Name:
LBDHCBLC
SAS Label:
Hexachlorobenzene comment code
English Text:
Hexachlorobenzene comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 264 264
1 Below lower detection limit 0 264
. Missing 0 264

LBCMIR - Mirex (ng/g)

Variable Name:
LBCMIR
SAS Label:
Mirex (ng/g)
English Text:
Mirex (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.0044 to 0.3758 Range of Values 264 264
. Missing 0 264

LBCMIRLA - Mirex Lipid Adj (ng/g)

Variable Name:
LBCMIRLA
SAS Label:
Mirex Lipid Adj (ng/g)
English Text:
Mirex Lipid Adj (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.5 to 62.5 Range of Values 264 264
. Missing 0 264

LBDMIRLC - Mirex comment code

Variable Name:
LBDMIRLC
SAS Label:
Mirex comment code
English Text:
Mirex comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 157 157
1 Below lower detection limit 107 264
. Missing 0 264

LBCODT - o,p'-DDT (ng/g)

Variable Name:
LBCODT
SAS Label:
o,p'-DDT (ng/g)
English Text:
o,p'-DDT (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.0043 to 0.0973 Range of Values 264 264
. Missing 0 264

LBCODTLA - o,p'-DDT Lipid Adj (ng/g)

Variable Name:
LBCODTLA
SAS Label:
o,p'-DDT Lipid Adj (ng/g)
English Text:
o,p'-DDT Lipid Adj (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.5 to 14 Range of Values 264 264
. Missing 0 264

LBDODTLC - o,p'-DDT comment code

Variable Name:
LBDODTLC
SAS Label:
o,p'-DDT comment code
English Text:
o,p'-DDT comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 13 13
1 Below lower detection limit 251 264
. Missing 0 264

LBCOXY - Oxychlordane (ng/g)

Variable Name:
LBCOXY
SAS Label:
Oxychlordane (ng/g)
English Text:
Oxychlordane (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.0044 to 0.3965 Range of Values 264 264
. Missing 0 264

LBCOXYLA - Oxychlordane Lipid Adj (ng/g)

Variable Name:
LBCOXYLA
SAS Label:
Oxychlordane Lipid Adj (ng/g)
English Text:
Oxychlordane Lipid Adj (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.8 to 56.3 Range of Values 264 264
. Missing 0 264

LBDOXYLC - Oxychlordane comment code

Variable Name:
LBDOXYLC
SAS Label:
Oxychlordane comment code
English Text:
Oxychlordane comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 249 249
1 Below lower detection limit 15 264
. Missing 0 264

LBCPDE - p,p'-DDE (ng/g)

Variable Name:
LBCPDE
SAS Label:
p,p'-DDE (ng/g)
English Text:
p,p'-DDE (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.172 to 77.3689 Range of Values 264 264
. Missing 0 264

LBCPDELA - p,p'-DDE Lipid Adj (ng/g)

Variable Name:
LBCPDELA
SAS Label:
p,p'-DDE Lipid Adj (ng/g)
English Text:
p,p'-DDE Lipid Adj (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
39.7 to 11200 Range of Values 264 264
. Missing 0 264

LBDPDELC - p,p'-DDE comment code

Variable Name:
LBDPDELC
SAS Label:
p,p'-DDE comment code
English Text:
p,p'-DDE comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 264 264
1 Below lower detection limit 0 264
. Missing 0 264

LBCPDT - p,p'-DDT (ng/g)

Variable Name:
LBCPDT
SAS Label:
p,p'-DDT (ng/g)
English Text:
p,p'-DDT (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.0044 to 6.7413 Range of Values 264 264
. Missing 0 264

LBCPDTLA - p,p'-DDT Lipid Adj (ng/g)

Variable Name:
LBCPDTLA
SAS Label:
p,p'-DDT Lipid Adj (ng/g)
English Text:
p,p'-DDT Lipid Adj (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.6 to 973 Range of Values 264 264
. Missing 0 264

LBDPDTLC - p,p'-DDT comment code

Variable Name:
LBDPDTLC
SAS Label:
p,p'-DDT comment code
English Text:
p,p'-DDT comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 217 217
1 Below lower detection limit 47 264
. Missing 0 264

LBCTNA - trans-Nonachlor (ng/g)

Variable Name:
LBCTNA
SAS Label:
trans-Nonachlor (ng/g)
English Text:
trans-Nonachlor (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.0044 to 0.8866 Range of Values 264 264
. Missing 0 264

LBCTNALA - trans-Nonachlor Lipid Adj (ng/g)

Variable Name:
LBCTNALA
SAS Label:
trans-Nonachlor Lipid Adj (ng/g)
English Text:
trans-Nonachlor Lipid Adj (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.8 to 122 Range of Values 264 264
. Missing 0 264

LBDTNALC - trans-Nonachlor comment code

Variable Name:
LBDTNALC
SAS Label:
trans-Nonachlor comment code
English Text:
trans-Nonachlor comment code
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 258 258
1 Below lower detection limit 6 264
. Missing 0 264