. 2018 Nov 22;126(11):117004. doi: 10.1289/EHP535

Table 3.

Some chemical classes of interest, biomarkers, and source materials used in MARBLES study.

Compound Class	Half-lives	Urine	Blood	Dust	Placenta	Cord Blood	Breast Milk	Food Frequency Questionnaires	Food Recalls	Environmental Questionnaires	GIS-Linked California Pesticide Use Report Database	Medical Records
Environmental xenobiotics	In the human body and environment^a
Pyrethroid Pesticides	Hours to a few days in human body (Barr et al. 2010); days to a year in sunlight outdoors; longer indoors (Laskowski 2002; Shin et al. 2013)	x		x					x	x	x
Brominated Flame Retardants (PBDEs)	Typically months in human body; persistent in the environment (Thuresson et al. 2006)		x	x			x
PBDE Hydroxy-metabolites	Little data found in humans regarding OH-PBDE half-lives, or their variability^b		x
Phthalates	Hours to days in human body (Braun et al. 2012; Koch and Angerer 2007; Koch et al. 2006; Meeker et al. 2012)	x		x						x		x
Nutrients
Folic acid or folate	1.5 to 31.5 hours for newly absorbed folic acid, and about 100 days for folate pool in human body (Krumdieck et al. 1978; Loew et al. 1987)		x		x	x		x
Vitamin B6	Minutes to an hour in human body (Zempleni 1995)		x			x		x
Vitamin B12	In human body, minutes for holotranscobalamin II (bioavailable form); 2 weeks for transcobalaminI and II (storage protein) (Bauman et al. 2000)		x			x		x
Iron	Differs by type from hours to days in the human body (Geisser and Burckhardt 2011)		x			x		x
Vitamin D	15 hours for calcitriol (active form) and 15 days for calcidiol (Jones 2008)
Biomarkers	In stored samples
Maternal antibodies to fetal brain	Unknown		x
Mitochondrial DNA	$Mean \pm SD$ : $62 \pm 28$ years^c (Lebedeva et al. 2000)		x		x
DNA methylation (whole genome bisulfite sequencing)	DNA and its modifications are stable for years if dried or frozen (Kader and Ghai 2015; Shabihkhani et al. 2014)				x	x
RNA/Gene Expression	RNA is stable for 5 years if human samples are frozen promptly and RNA is isolated directly from frozen samples (Shabihkhani et al. 2014)		x			x
Metabolomics	Differs by compound and medium (Saude and Sykes 2007; Haid et al. 2018) with about half of compounds stable up to 5 years at $- 80 ° C$ in blood (Haid et al. 2018).	x	x		x	x	x

Note: Table includes analytes for which past or current funding covers measurements in at least one medium; other sources and media are also shown, whether or not funded for assays. Additional media collected in MARBLES include: hair, saliva, maternal vaginal secretions, newborn meconium, and fecal specimens.

^{^a}

Half-lives in both the environment and the body vary by specific compound or congener within a class: ranges are provided.

^{^b}

Some OH-PBDEs in the body are formed through transformation of PBDEs, and therefore temporal variation also depends on half-lives of PBDEs, as well as metabolic rates to form and remove OH-PBDEs.

^{^c}

To ensure the rigor and scientific reproducibility of data, the reported half-life for mtDNA integrity in PBMCs and placenta (expressed as $mean \pm SD$ ; $n = 50$ ) was experimentally determined in Giulivi’s laboratory assuming a pseudo-first order kinetics. The value is within that reported for mtDNA in hair shafts. Upon receipt of frozen samples, DNA was always extracted within a day. The extracted DNA was stored at $- 20 ° C$ in $0.5 mM$ EDTA, $10 mM$ Tris-Cl (pH 9.0) at a concentration of $200 ng / μ l$ . After outcomes are determined by qRTPCR, the mtDNA is stored at $- 80 ° C$ .