National Health and Nutrition Examination Survey

Beginning in NHANES 2013-2014, the Environmental Phenols and Parabens dataset (formerly EPH) was combined with the Pesticides - Environmental - Urine dataset (formerly PP) and renamed Personal Care and Consumer Product Chemicals and Metabolites (EPHPP_H).

Biomonitoring of environmental phenols, parabens, and triclocarban is used to assess prevalence and relevance of exposure in public health. The routes of human exposure to these compounds include industrial pollution, pesticide use, food consumption, and use of personal care products.

Bisphenol A (BPA) is used in the manufacture of polycarbonate plastics and epoxy resins, which can be used in protective coatings on food containers and as composites and sealants in dentistry. Concerns over potential health risks of BPA have led to restrictions on the use of BPA in certain baby and children products (U.S. Food and Drug Administration 2014). BPA alternatives, such as bisphenol S (BPS, 4,4'-sulfonyldiphenol) and bisphenol F (BPF, 4,4′-dihydroxydiphenylmethane), have been introduced in the market to replace BPA (Liao et al. 2012). Some phenols are used as sunscreen agents for skin protection, and as UV filters in cosmetic products and plastics to improve stability (e.g., benzophenone-3). Phenols are also used as bactericides (e.g., triclosan) in soap and are found in other personal care products. Other chlorophenols have been used in the wood preservation industry as intermediates in the production of pesticides, and as disinfectants or fungicides for industrial and indoor home use. The manufacture of certain chlorinated aromatic compounds can also produce chlorophenols as byproducts.

Parabens, a group of alkyl (e.g., methyl, ethyl, propyl, butyl) esters of p-hydroxybenzoic acid, are widely used as antimicrobial preservatives in personal care products, and can also be used in pharmaceuticals, as well as in food and beverage processing.

Triclocarban (3,4,4’-trichlorocarbanilide) can be used as an antimicrobial agent in consumer and personal care products (e.g., bar soap), as well as in cleansing preparations in hospitals and other medical settings.

Examined participants aged 6 years and older from a one-third sample were eligible.

A sensitive method for measuring BPA, benzophenone-3, triclosan, four parabens, two dichlorophenols, and triclocarban was developed based on a previously published approach (Zhou et al, 2014). The method uses on-line solid phase extraction coupled to high performance liquid chromatography and tandem mass spectrometry. With the use of isotopically labeled internal standards, the detection limits in 100 μL of urine are 0.1 – 1.7 micrograms per liter (μg/L), sufficient for measuring urinary levels of phenols, parabens, and triclocarban in non-occupationally exposed subjects.

Refer to the Laboratory Method Files section for detailed laboratory procedure manual(s) of the methods used.

There were no changes to the lab method, lab equipment, or lab site for this component in the NHANES 2013-2014 cycle.

Personal Care and Consumer Product Chemicals and Metabolites (Updated September 2016)

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 Procedures Manual (LPM). Vials are stored under appropriate frozen (–20°C) conditions until they are shipped to 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 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.

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 on “dry run” sessions. In addition, contract laboratories randomly perform repeat testing on 2.0% of all specimens.

NCHS developed and distributed a quality control protocol for all the contract laboratories which outlined the Westgard rules (Westgard et al, 1981) used 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. 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 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 2013-2014 Laboratory Data Overview for general information on NHANES laboratory data.

Subsample weights

Urinary environmental phenols, parabens and triclocarban were measured in a one third subsample of persons 6 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.

Demographic and Other Related Variables

The analysis of NHANES laboratory data must be conducted with the key survey design and basic demographic variables. The NHANES 2013-2014 Demographic Data 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.

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

Detection Limits

The detection limits were constant for all of the analytes in the data set. Two variables are provided for each of these analytes. The variable name ending in “LC” (ex., URDBPHLC) 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 lower limit of detection (ex., URDBPHLC=1), an imputed fill value was placed in the analyte results field. This value is the lower limit of detection divided by square root of 2 (LLOD/sqrt[2]). The other variable prefixed URX (ex., URXBPH) provides the analytic result for that analyte.

The lower limits of detection (LLOD, in μg/L) for the environmental phenols, parabens, and triclocarban are:

Please refer to the NHANES Analytic Guidelines and the on-line NHANES Tutorial for further details on the use of sample weights and other analytic issues.