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

Examined participants aged 12 years and older from a one-third sample were eligible.

Description of Laboratory Methodology

Serum samples from NHANES 2013-2014 were stored frozen before analysis. Eight organochlorine pesticides and metabolites were measured in serum using 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 Methods File 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 2013-2014 cycle.

Laboratory Method Files

Pesticides - Organochlorine Pesticides (May 2018)

Laboratory Quality Assurance and Monitoring

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 Procedures 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).

Data Processing and Editing

The data were reviewed. Incomplete data or improbable values were sent to the performing laboratory for confirmation.

Analytic Notes

Refer to the 2013-2014 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 48 demographic groups. The analysis of NHANES 2013-2014 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 2013-2014 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 U.S. 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 U.S. 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 2013-2014, 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 subsample of the NHANES 2013-2014 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 48 demographic groups based on race and Hispanic origin (Mexican American: MA, Other Hispanic: OH, non-Hispanic white: NHW, non-Hispanic black: NHB, non-Hispanic Asian: NHA, 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 48 demographic groups varied depending on the total number of individual samples available in a demographic group. The one-third subsample of NHANES 2013-2014 represents 2,318 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, 2,179 samples were available to create 284 pools with 8 samples per pool. For NHANES 2013-2014, due to limited sample size, no pooled sample was formed for males 60 years and older in the “OTHER” race/Hispanic origin group. Data user needs to be cautious when making national inference including this population subgroup. See more details on pool sample formation and exceptions in Table 2. The variable SAMPLEID denotes the identification number for each pool and ranges from 1 through 284. Please refer to the Pooled-Sample Technical Support file (POOLTF_H) 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 10. The individual samples were sorted/stratified by sampling weight within each of the 48 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 subsample, 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 WTBSMSMA.

Demographic and Other Related Variables

The analysis of NHANES laboratory data must be conducted using the appropriate survey design and demographic variables. The NHANES 2013-2014 Demographics File contains demographic data, health indicators, and other related information collected during household interviews as well as the 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.

The Fasting Questionnaire File includes auxiliary information, such as fasting status, length of fast, and the time of venipuncture.

This laboratory data file can be linked to the other NHANES data files using the unique survey participant identifier (i.e., SEQN).

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.*

Variable

Common

IUPAC Name

Max LOD

Name

Abbrev.

(pg/g serum)

(ng/g lipid)

LBCHCB

HCB

Hexachlorobenzene

5.0

1.3

LBCBHC

B-HCCH

BETA-Hexachlorocyclohexane

5.0

1.3

LBCOXY

OXYCHLOR

Oxychlordane

5.0

1.3

LBCTNA

T-NONA

Trans-Nonachlor

5.0

1.3

LBCPDE

PP-DDE

2,2-Bis(4-chlorophenyl)-1,1-dichloroethene

7.0

1.8

LBCPDT

PP-DDT

2,2-Bis(4-chlorophenyl-1,1,1-trichloroethan

5.0

1.3

LBCMIR

MIREX

Mirex

5.0

1.3

         *Maximum limit of detection (MLOD) expressed as pg/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 2013-2014 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

(RIDRETH3=1) 1

Male

(RIAGENDR=1) 1

56/51/502

(7)

40/39/393

(5)

42/41/40

(5)

34/34/32

(4)

Female

(RIAGENDR=2)

54/50/504

(7)

39/38/385

(5)

43/43/436

(6)

42/38/385

(5)

Other Hispanics

(RIDRETH3=2)

Male

(RIAGENDR=1)

21/19/197

(3)

19/19/197

(3)

28/28/288

(4)

24/23/239

(3)

Female

(RIAGENDR=2)

22/22/2210

(3)

30/29/2911

(4)

33/32/32

(4)

34/33/32

(4)

Non-Hispanic White

(RIDRETH3=3)

Male

(RIAGENDR=1)

67/63/6312

(8)

117/112/11113

(14)

111/106/10414

(14)

132/130/13015

(17)

Female

(RIAGENDR=2)

56/49/48

(6)

122/121/120

(15)

131/125/12516

(16)

165/160/15817

(20)

Non-Hispanic Black

(RIDRETH3=4)

Male

(RIAGENDR=1)

61/48/48

(6)

65/57/56

(7)

57/53/5318

(7)

74/67/6719

(9)

Female

(RIAGENDR=2)

57/47/4520

(6)

69/64/64

(8)

66/62/6221

(8)

65/61/6022

(8)

Non-Hispanic Asian

    (RIDRETH3=6)

Male

(RIAGENDR=1)

23/18/1823

(3)

32/30/3024

(4)

34/31/3125

(4)

27/25/24

(3)

Female

(RIAGENDR=2)

29/19/197

(3)

40/39/393

(6)

53/52/5226

(7)

23/23/239

(3)

Other Race  including  Multiracial

(RIDRETH3=7)

Male

(RIAGENDR=1)

9/9/8

(1)

18/17/16

(2)

12/11/1127

(2)

2/2/028

(0)

Female

(RIAGENDR=2)

12/11/1129

(2)

16/16/16

(2)

9/9/8

(1)

3/3/330

(1)

1 Value of this categorical variable in the data set; 2 50 Usable samples: five 8 sample, one 7 sample and one 3 sample pool were created;
3 39 Usable: four 8 sample and one 7 sample pool; 4 50 Usable: six 8 sample and one 2 sample pool; 5 38 Usable: four 8 sample and one 6 sample pools; 6 43 Usable: five 8 sample and one 3 sample pool; 7 19 Usable: two 8 sample and one 3 sample pool; 8 28 Usable: three 8 sample and one 4 sample pool; 9 23 Usable: two 8 sample and one 7 sample pool; 10 22 Usable: two 8 sample and one 6 sample pool; 11 29 Usable: three 8 sample and one 5 sample pool; 12 63 Usable: seven 8 sample and one 7 sample pool; 13 111 Usable: thirteen 8 sample and one 7sample pool; 14 104 Usable: eleven 8 sample, two 7 sample and one 2 sample pool; 15 130 Usable: fifteen 8 sample, one 7 sample and one 3 sample pool; 16 125 Usable: fifteen 8 sample and one 5 sample pool; 17 158 Usable: nineteen 8 sample and one 6 sample pool; 18 53 Usable: six 8 sample and one 5 sample pool; 19 67 Usable: eight 8 sample and one 3 sample pool; 20 45 Usable: five 8 sample and one 5 sample pool; 21 62 Usable: seven 8 sample and one 6 sample pool; 22 60 Usable: seven 8 sample and one 4 sample pool; 23 18 Usable: two 8 sample and one 2 sample pool; 24 30 Usable: three 8 sample and one 6 sample pool; 25 31 Usable: three 8 sample and one 7 sample pool; 26 52 Usable: six 8 sample and one 4 sample pool; 27 11 Usable: one 7 sample and one 4 sample pool; 28 0 Usable: no pool formed; 29 11 Usable: one 8 sample and one 3 sample pool; 30 3 Usable: one 3 sample pool.

Methodological approaches for analysis

There are a few pooled-sample methodological publications, which address approaches related to the following topics:

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
Code or Value Value Description Count Cumulative Skip to Item
1 to 284 Range of Values 284 284
. Missing 0 284

RIDRETH3 - Race/Hispanic Origin

Variable Name:
RIDRETH3
SAS Label:
Race/Hispanic Origin
English Text:
Recode of reported race and Hispanic origin information
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Mexican American 44 44
2 Other Hispanic 28 72
3 Non-Hispanic White 110 182
4 Non-Hispanic Black 59 241
6 Non-Hispanic Asian 32 273
7 Other Race, Including Multiracial 11 284
. Missing 0 284

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 55 55
2 20-39 years 74 129
3 40-59 years 78 207
4 60+ years 77 284
. Missing 0 284

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 135 135
2 Female 149 284
. Missing 0 284

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
2 to 8 Range of Values 284 284
. Missing 0 284

WTBSMSMA - Sum of adjusted subsample B weights

Variable Name:
WTBSMSMA
SAS Label:
Sum of adjusted subsample B weights
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
63628.672969 to 3656105.4719 Range of Values 284 284
. Missing 0 284

LBCBHC - Beta-hexachlorocyclohexane (pg/g)

Variable Name:
LBCBHC
SAS Label:
Beta-hexachlorocyclohexane (pg/g)
English Text:
Beta-hexachlorocyclohexane (pg/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3.536 to 5648 Range of Values 281 281
. Missing 3 284

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

Variable Name:
LBCBHCLA
SAS Label:
B-hexachlorocyclohexane Lipid Adj (ng/g)
English Text:
Beta-hexachlorocyclohexane Lipid Adjusted (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.5162 to 853.4 Range of Values 281 281
. Missing 3 284

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 216 216
1 Below lower detection limit 65 281
. Missing 3 284

LBCHCB - Hexachlorobenzene (pg/g)

Variable Name:
LBCHCB
SAS Label:
Hexachlorobenzene (pg/g)
English Text:
Hexachlorobenzene (pg/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
23.57 to 160.8 Range of Values 284 284
. Missing 0 284

LBCHCBLA - Hexachlorobenzene Lipid Adj (ng/g)

Variable Name:
LBCHCBLA
SAS Label:
Hexachlorobenzene Lipid Adj (ng/g)
English Text:
Hexachlorobenzene Lipid Adjusted (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
5.058 to 27.83 Range of Values 284 284
. Missing 0 284

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 284 284
1 Below lower detection limit 0 284
. Missing 0 284

LBCMIR - Mirex (pg/g)

Variable Name:
LBCMIR
SAS Label:
Mirex (pg/g)
English Text:
Mirex (pg/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3.536 to 633.5 Range of Values 284 284
. Missing 0 284

LBCMIRLA - Mirex Lipid Adj (ng/g)

Variable Name:
LBCMIRLA
SAS Label:
Mirex Lipid Adj (ng/g)
English Text:
Mirex Lipid Adjusted (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.4313 to 118.2 Range of Values 284 284
. Missing 0 284

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 182 182
1 Below lower detection limit 102 284
. Missing 0 284

LBCOXY - Oxychlordane (pg/g)

Variable Name:
LBCOXY
SAS Label:
Oxychlordane (pg/g)
English Text:
Oxychlordane (pg/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3.536 to 335.1 Range of Values 284 284
. Missing 0 284

LBCOXYLA - Oxychlordane Lipid Adj (ng/g)

Variable Name:
LBCOXYLA
SAS Label:
Oxychlordane Lipid Adj (ng/g)
English Text:
Oxychlordane Lipid Adjusted (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.7071 to 64.58 Range of Values 284 284
. Missing 0 284

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 281 281
1 Below lower detection limit 3 284
. Missing 0 284

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

Variable Name:
LBCPDE
SAS Label:
p,p'-DDE (pg/g)
English Text:
p,p'-dichlorodiphenyltrichloroethene (pg/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
147.9 to 18720 Range of Values 284 284
. Missing 0 284

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

Variable Name:
LBCPDELA
SAS Label:
p,p'-DDE Lipid Adj (ng/g)
English Text:
p,p'-dichlorodiphenyltrichloroethene Lipid Adjusted (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
32.3 to 2809 Range of Values 284 284
. Missing 0 284

LBDPDELC - p,p'-DDE comment code

Variable Name:
LBDPDELC
SAS Label:
p,p'-DDE comment code
English Text:
p,p'-dichlorodiphenyltrichloroethene 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 284 284
1 Below lower detection limit 0 284
. Missing 0 284

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

Variable Name:
LBCPDT
SAS Label:
p,p'-DDT (pg/g)
English Text:
p,p'-dichlorodiphenyltrichlorethane (pg/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3.536 to 1030 Range of Values 283 283
. Missing 1 284

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

Variable Name:
LBCPDTLA
SAS Label:
p,p'-DDT Lipid Adj (ng/g)
English Text:
p,p'-dichlorodiphenyltrichlorethane Lipid Adjusted (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.601 to 188.1 Range of Values 283 283
. Missing 1 284

LBDPDTLC - p,p'-DDT comment code

Variable Name:
LBDPDTLC
SAS Label:
p,p'-DDT comment code
English Text:
p,p'-dichlorodiphenyltrichlorethane 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 263 263
1 Below lower detection limit 20 283
. Missing 1 284

LBCTNA - trans-Nonachlor (pg/g)

Variable Name:
LBCTNA
SAS Label:
trans-Nonachlor (pg/g)
English Text:
trans-Nonachlor (pg/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3.536 to 586.4 Range of Values 284 284
. Missing 0 284

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

Variable Name:
LBCTNALA
SAS Label:
trans-Nonachlor Lipid Adj (ng/g)
English Text:
trans-Nonachlor Lipid Adjusted (ng/g)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.7778 to 105.7 Range of Values 284 284
. Missing 0 284

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 283 283
1 Below lower detection limit 1 284
. Missing 0 284