Table of Contents

Component Description

N,N-diethyl-3-methylbenzamide, commonly known as DEET, has become a widely used insect repellent in the United States.  DEET is highly effective against a broad spectrum of insect pests, including potential disease vectors such as mosquitoes, biting flies and ticks (CDC 2015). More than 500 products are currently registered with the Environmental Protection Agency in a variety of liquids, lotions, gels, sprays, sticks and impregnated materials with DEET concentrations ranging from 5 to 98% (EPA 2017). Every year, approximately one-third of the U.S. population uses DEET-containing insect repellents (CDC, 2009), and exposure to DEET is widespread (Calafat 2016). Urinary metabolites of DEET are more sensitive biomarkers of exposure than DEET itself; in fact, relying on DEET as an exposure biomarker can lead to exposure misclassification (Calafat 2016, ATSDR, 2017).

To better understand exposure to DEET we measured one DEET metabolite, 3-(ethylcarbamoyl)benzoic acid in a one-third subsample of participants 3+ years of age from NHANES 2015-2016. 

Eligible Sample

One-third subsample of participants aged 3+ years from NHANES 2015-2016 with stored urine (N=3,045).

Description of Laboratory Methodology

The method uses 0.2 mL urine and is based on enzymatic hydrolysis of urinary conjugates of the target analytes, online solid phase extraction, reversed phase high-performance liquid chromatography separation, and isotope dilution-electrospray ionization tandem mass spectrometry detection (Baker et al. 2018).

Laboratory Quality Assurance and Monitoring

The analytical measurements were conducted following strict quality control/quality assurance CLIA guidelines. Along with the study samples, each analytical run included high- and low-concentration quality control materials (QCs) and reagent blanks to assure the accuracy and reliability of the data. The concentrations of the high-concentration QCs and the low-concentration QCs, averaged to obtain one measurement of high-concentration QC and low-concentration QC for each run, were evaluated using standard statistical probability rules (Caudill et al. 2008).

Data Processing and Editing

Data were received after all analyses were complete. The data were not edited.   Data Access: All data are publicly available.

Analytic Notes

Detection Limits

The detection limits were constant for all of the analytes in the data set. Two variables are provided for each analyte. The variable name ending in “L” (ex., SSMEAL) indicates whether the result was below the limit of detection: the value “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 limit of detection (ex.,SSMEAL=1), an imputed fill value was placed in the analyte results field. This value is the limit of detection divided by square root of 2 (LOD/√2). The other variable prefixed SS (ex., SSMEA) provides the analytic result for that analyte.

The limit of detection (LOD, in µg/L) for MEA:

Variable Name

SAS Label

LOD

SSEMEA

3-(Ethylcarbamoyl)benzoic acid (µg/L)

0.20

 

Interferences:

Blanks in an analyte results field represent missing values in cases when the presence of interferences precluded obtaining a valid numeric result for a given analyte.


References

Codebook and Frequencies

SEQN - Respondent sequence number

Variable Name:
SEQN
SAS Label:
Respondent sequence number
English Text:
Respondent sequence number.
Target:
Both males and females 3 YEARS - 150 YEARS

SSEMEA - 3-(Ethylcarbamoyl)benzoic acid (ug/L)

Variable Name:
SSEMEA
SAS Label:
3-(Ethylcarbamoyl)benzoic acid (ug/L)
English Text:
3-(Ethylcarbamoyl)benzoic acid (ug/L)
Target:
Both males and females 3 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.14 to 17500 Range of Values 2964 2964
. Missing 69 3033

SSEMEAL - 3-(Ethylcarbamoyl)benzoic acid Cmt code

Variable Name:
SSEMEAL
SAS Label:
3-(Ethylcarbamoyl)benzoic acid Cmt code
English Text:
3-(Ethylcarbamoyl)benzoic acid Cmt code
Target:
Both males and females 3 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2250 2250
1 Below lower detection limit 714 2964
. Missing 69 3033

WTSB2YR - 1/3 subsample weights

Variable Name:
WTSB2YR
SAS Label:
1/3 subsample weights
English Text:
1/3 subsample weights
Target:
Both males and females 3 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
6552.119284 to 874638.01159 Range of Values 3033 3033
. Missing 0 3033