title: Urinary metabolites of organophosphate flame retardants and their variability in pregnant women.
abstract: Organophosphate flame retardants (OPFRs) are commonly added to consumer products to reduce their flammability. Based on levels of OPFRs in indoor environments, human exposure is likely chronic and ubiquitous. Animal studies suggest that exposure to some OPFRs may result in adverse health impacts, particularly for Tris (1,3-dichloropropyl) phosphate (TDCPP); however, human data on the impacts of exposure to OPFRs are lacking. To design human studies, more information is needed on the stability of measured OPFRs in human samples over time. In this study, we sought to assess the degree of temporal variability of urinary TDCPP and triphenyl phosphate (TPP) metabolites throughout pregnancy in a cohort of women from central North Carolina. Eight pregnant women provided multiple urine samples: 3 during the 18th week of pregnancy, 1 during the 28th week, and 1 shortly after the child's birth. Bis (1,3-dichloropropyl) phosphate (BDCPP) and diphenyl phosphate (DPP), the respective metabolites of TDCPP and TPP, were measured in urine samples using liquid chromatography-tandem mass spectrometry. BDCPP and DPP were each detected in 38 of 39 urine samples and were not normally distributed. Geometric mean BDCPP and DPP concentrations were 1.3ng/mL (interquartile range (IQR): 0.8, 2.7ng/mL) and 1.9ng/mL (IQR: 0.9, 3.5ng/mL), respectively. BDCPP and DPP were moderately to strongly reliable over one week (intraclass correlation coefficient (ICC)=0.5; 95% confidence interval (CI): 0.4, 0.7 and ICC=0.7; 95% CI: 0.5, 0.8, respectively), and over the entire pregnancy (ICC=0.5 95% CI: 0.3, 0.7 and ICC=0.6; 95% CI: 0.4, 0.7, respectively). These data suggest that exposures to TDCPP and TPP are widespread and variable for pregnant women, and that a single measure of BDCPP or DPP, taken in the second trimester, likely captures information on the rank order of exposure throughout pregnancy.
authors: Nicholas School of the Environment, Duke University, LSRC, Box 90328, Durham, NC 27708, USA; Gillings School of Global Public Health, University of North Carolina, 135 Dauer Drive, Campus Box 7435, Chapel Hill, NC 27599, USA. Electronic address: kate.hoffman@duke.edu.
authors: Kate
authors: K
authors: Hoffman
authors: Gillings School of Global Public Health, University of North Carolina, 135 Dauer Drive, Campus Box 7435, Chapel Hill, NC 27599, USA. Electronic address: julie_daniels@unc.edu.
authors: Julie L
authors: JL
authors: Daniels
authors: Nicholas School of the Environment, Duke University, LSRC, Box 90328, Durham, NC 27708, USA. Electronic address: heather.stapleton@duke.edu.
authors: Heather M
authors: HM
authors: Stapleton
mesh_terms: D000328:Adult; D000818:Animals; D002853:Chromatography, Liquid; D005260:Female; D005411:Flame Retardants / Q000378:metabolism*; D006801:Humans; D009657:North Carolina; D010755:Organophosphates / Q000378:metabolism / Q000652:urine*; D009943:Organophosphorus Compounds / Q000652:urine*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second / Q000652:urine*
chemical_list: D005411:Flame Retardants; D010755:Organophosphates; D009943:Organophosphorus Compounds; C588130:bis(1,3-dichloropropyl)phosphate; C012085:tris(2,3-dibromopropyl)phosphate; C005445:triphenyl phosphate
keywords: BDCPP; CI; DPP; GM; ICC; IQR; MDL; ND; OPFRs; Organophosphate flame retardants (OPFRs); PBDEs; Pregnant women; SG; TDCPP; TPP; Triphenyl phosphate (TPP); Tris (1,3-dichloropropyl) phosphate; Tris (1,3-dichloropropyl) phosphate (TDCPP); Urine; Variability; bis (1,3-dichloropropyl) phosphate; confidence interval; diphenyl phosphate; geometric mean; interquartile range; intraclass correlation coefficient; method detection limit; non-detect; organophosphate flame retardants; polybrominated diphenyl ethers; specific gravity; triphenyl phosphate