• Component Description
• Eligible Sample
• Description of Laboratory Methodology
• Laboratory Quality Assurance and Monitoring
• Data Processing and Editing
• Analytic Notes
• References
• Codebook
  • SEQN - Respondent sequence number
  • WTSSTP2Y - Surplus specimen terpenes 2 yr weights
  • SSSAPN - α-Pinene (ng/mL)
  • SSSAPNL - α-Pinene Comment Code
  • SSSBPN - β-Pinene (ng/mL)
  • SSSBPNL - β-Pinene Comment Code
  • SSSLIM - Limonene (ng/mL)
  • SSSLIML - Limonene Comment Code

National Health and Nutrition Examination Survey

2013-2014 Data Documentation, Codebook, and Frequencies

Terpenes – Serum (Surplus) (SSTERP_H)

Data File: SSTERP_H.xpt

First Published: April 2023

Last Revised: NA

Component Description

Terpenes and their derivatives are common tropospheric trace gases (Graedel, 1979). They are emitted by many species of vegetation and are best known as the group of compounds responsible for the pleasant and distinctive odor of pine forests. Most vegetation emits an array of volatile organic compounds (VOCs) (Geron et. al., 2000). The major components of conifer-derived VOCs are monoterpenes (MTs), such as α-pinene, β-pinene, β-myrcene, Δ-3-carene, and limonene. According to the documented physicochemical properties of MTs (Falk A et. al., 1990) they are sparingly soluble in water but are soluble in blood and lipophilic tissues. Α- and β-Pinene dominate emissions from conifer trees; and research investigations have raised concerns regarding the physiological effect of α-pinene on humans (Nielsen et. al., 2005; Falk A.A. et. al., 1990). Exposure to high concentrations of α-pinene (10–450 mg/m³) causes an increase in its concentration in the blood (Falk A.A. et. al., 1990) and human metabolism of α-pinene has also been documented (Levin, 1996; Vanek et. al., 2005). Terpenes are also a major component of plant resins (Paduch et. al., 2007). In plants they function as infochemicals, attractants, or repellents, as they are responsible for the typical fragrance of many plants (Crowell, 1997; Theis et. al., 2003). In addition, terpenes are added to e-cigarette fluids as flavor chemicals (Tierney et. al., 2016).

There is concern for potential health impacts of secondary organic compounds formed via terpene oxidation reactions (Rohr, 2013). These compounds exhibit active indoor air chemistry (ozone-initiated terpene chemistry), resulting in highly reactive intermediates that can exacerbate susceptible populations. For example, α-pinene and limonene are commonly found in air fresheners and cleaning products. One study in an experimental room with cleaning products reported 1-hour concentrations of individual terpenoids ranging from 10 to 1,300 μg/m³ (1.8–234 ppb) (Singer et. al., 2006). The presence of these terpenes in high concentrations present a potential hazard due to their reactivity with ozone. The main reaction products of α-pinene/ozone reactions are formaldehyde and other aldehydes, such as pinonaldehyde (Grosjean et. al., 1992).

Many of the terpene/ozone reaction products are asthma triggers; terpenes are a significant factor in the initiation, exacerbation, and propagation of some cases of chemical sensitivity. Studies performed on health-care personnel and professional cleaners working in hospitals have shown an increased risk of work-related asthma due to the exposure to traditional cleaning agents (e.g., detergents), especially if cleaning agents and disinfectants are used in their sprayed form (Dumas et. al., 2012). In Asia and Europe, nurses have shown an increased risk of hospitalization for asthma and new-onset asthma if exposed to cleaning agents (Dumas et. al., 2012).

The MTs α-pinene and β-pinene are irritating to skin and mucous membranes and can cause both allergic and non-allergic contact dermatitis (Parmeggiani, 1984; Pirila et. al., 1958). Few studies have investigated whether the ability of terpenes to facilitate chemical absorption correlates with increased irritation potentials. However, studies (Mandanha et. al., 2013) have demonstrated that MTs are strong membrane fluidizers in erythrocyte and fibroblast cells, and the observed effects were not significantly different among them, suggesting that they possess the same potency in enhancing dermal permeation. However, there are no reports of serum toxicity for these terpenes. Falk et. al. (1991) observed a long half-time in blood, indicating the terpene’s affinity for adipose tissues.

Eligible Sample

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

Description of Laboratory Methodology

This method was based on headspace solid phase microextraction coupled to gas chromatography-tandem mass spectrometry (HS-SPME-GC-MS/MS) (Silva et. al., 2018).  This method required the use of 0.50 mL of serum that was spiked with 40 µL of isotopically labeled internal standard before being hermetically sealed in a 10-mL SPME vial with a Teflon-lined silicone septum. After automated headspace sampling, the SPME fiber was injected into the GC inlet to undergo separation using a DB-624 column. The eluates were ionized at 70eV in the electron source of the mass spectrometer. The tandem mass spectrometer ran in Multiple Reaction Monitoring (MRM) mode where the precursor ions fragmented with nitrogen gas in the collision cell at a defined electron voltage. The resultant product ions registered an interpretable signal via the electron multiplier. The relative response ratio (native to internal standard signal) was compared with a calibration curve of known standards to quantitate the concentration of the individual terpene in the matrix.

Laboratory Quality Assurance and Monitoring

Serum specimens 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 (–20°C) conditions until they are shipped to National Center for Environmental Health for testing.

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 QC 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

All QC procedures recommended by the manufacturers were followed. Reported results for all assays meet the Division of Laboratory Sciences’ QA/QC 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.

There are over 800 laboratory tests performed on NHANES participants. However, not all participants provided biospecimens or enough volume for all the tests to be performed. Additionally, availability of specimens for surplus projects is lower than for other laboratory tests performed on NHANES participants. The specimen availability can also vary by age or other population characteristics. Analysts should evaluate the extent of missing data in the dataset related to the outcome of interest as well as any predictor variables used in the analyses to determine whether additional re-weighting for item non-response is necessary.

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

Subsample Weights

The analytes included in this dataset were measured in a one-third subsample of participants 6 years and older. Special sample weights are required to analyze these data properly. Specific sample weights for this subsample, WTSSTP2Y, are included in this data file and should be used when analyzing these data. The sample weights created for this file used the examination sample weight, i.e., WTMEC2YR, as the base weight. The base weight was adjusted for additional nonresponse to these lab tests and re-poststratified to the population total using sex, age, and race and Hispanic origin. Participants who were part of the eligible population but did not provide a serum specimen, did not have sufficient volume of biospecimens, or did not give consent for their specimens to be used for future research are included in the file; however, they have a sample weight assigned “0” in their records.

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.

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 the analytes in the data set. Two variables are provided for each of these analytes. The variable name ending in “L” (ex., SSSAPNL) 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. The other variable (ex., SSSAPN) provides the analytic result for the analyte. For analytes with analytic results below the lower limit of detection (ex., SSSAPNL =1), an imputed fill value was placed in the analyte results field. This value is the lower limit of detection divided by the square root of 2 (LLOD/sqrt [2]). All data are rounded to three significant figures or the precision of the LLOD, whichever is less precise.

The lower limit of detection (LLOD, in ng/mL) for SSSAPN, SSSBPN, and SSSLIM are:

Variable Name	SAS Label	LLOD
SSSAPN	a-Pinene (ng/mL)	0.0500
SSSBPN	ß-Pinene (ng/mL)	0.0560
SSSLIM	Limonene (ng/mL)	0.162

References

• Caudill, S.P., Schleicher, R.L., Pirkle, J.L. Multi-rule quality control for the age-related eye disease study. Statist. Med. (2008) 27(20):4094-4106.
• Crowell, P.L. Monoterpenes in breast cancer chemoprevention. Breast Cancer Res. Treat. (1997) 46:191-197.
• Dumas, O., Donnay, C., Heederik D.J., et. al. Occupational exposure to cleaning products and asthma in hospital workers. Occup. Environ. Med. (2012) 69:883-889.
• Falk A., Gullstrand E., Lof A., Wigaeus-Hjelm E. Liquid/air partition coefficients of four terpenes. Br. J. Ind. Med. (1990) 47:62-64.
• Falk A., Lof A., Hagberg M., Hjelm E.W., Wang Z. Human exposure to 3-carene by inhalation: toxicokinetics, effects on pulmonary function and occurrence of irritative and CNS symptoms. Toxicol. Appl. Pharmacol. (1991) 110:198-205.
• Falk A.A., Hagberg M.T., Löf A.E., Wigaeus-Hjelm E.M., Zhiping W. Uptake, distribution and elimination of α-pinene in man after exposure by inhalation. Scandinavian J. Work Environ. Health. (1990) 16(5):372-378.
• Geron C., Rasmussen R., Arnts R.R., Guenther A. A review and synthesis of monoterpene speciation from forests in the United States. Atmos. Environ. (2000) 34(11):1761-1781.
• Graedel T. Terpenoids in the atmosphere. Rev. Geophys. (1979) 17(5):937-947.
• Grosjean D., Williams E.L., Seinfeld J.H. Atmospheric oxidation of selected terpenes and related carbonyls: gas-phase carbonyl products. Environ. Sci. Technol. (1992) 26(8):1526-1533.
• Levin J-O. Gas chromatographic-mass spectrometric identification of metabolites from α-pinene in human urine after occupational exposure to sawing fumes. J Chromatogr B Biomed Sci Appl. (1996) 677(1):85-98.
• Nielsen G.D., Larsen S.T., Hougaard K.S., et. al. Mechanisms of Acute Inhalation Effects of (+) and (−)‐α‐Pinene in BALB/c Mice. Basic Clin. Pharmacol. Toxicol. (2005) 96(6):420-428.
• Paduch R., Kandefer-Szerszeń M., Trytek M., Fiedurek J. Terpenes: substances useful in human healthcare. Arch. Immunol. Ther. Exp. (2007) 55(5):315-327.
• Parmeggiani L. Encyclopaedia of occupational health and safety. J. R. Soc. Med. (1984) 77(11):987-988.
• Pirila V., Siltanen E. On the chemical nature of the eczematogenic agent in oil of turpentine. III. Dermatologica. (1958) 117(1): 1-8.
• Rohr A.C. The health significance of gas- and particle-phase terpene oxidation products: a review. Environ. Int. (2013) 60:145-162.
• Silva L.K., Hile G.A., Capella K.M., et. al. Quantification of 19 aldehydes in human serum by headspace SPME/GC/High-resolution mass spectrometry. Environ. Sci. Technol. (2018) 52(18):10571-10579.
• Singer B.C., Destaillats H., Hodgson A.T., Nazaroff W.W. Cleaning products and air fresheners: emissions and resulting concentrations of glycol ethers and terpenoids. Indoor Air. (2006) 16(3):179-191.
• Theis N., Lerdau M. The evolution of function in plant secondary metabolites. Int. J. Plant Sci. (2003) 164(33):S93-S102.
• Tierney P.A., Karpinski C.D., Brown J.E., Luo W., Pankow J.F. Flavour chemicals in electronic cigarette fluids. Tob. Control. (2016) 25:e10-15.
• Vanek T., Halik J., Vankova R., Valterova I. Formation of trans-verbenol and verbenone from α-pinene catalysed by immobilised Picea abies cells. Biosci. Biotechnol. Biochem. (2005) 69(2):321-325.

Codebook and Frequencies