Abstract
Background
Organophosphate esters (OPEs) have replaced flame retardant polybrominated diphenyl ethers as flame retardants in consumer products, but few longitudinal studies have characterized childhood OPE exposure.
Objective
We aimed to examine the exposure pattern of urinary OPE metabolites in children.
Methods
We quantified three urinary OPE metabolites five times in children (1, 2, 3, 5, 8 years) from 312 mother-child pairs in the Health Outcomes and Measures of the Environment (HOME) Study, a prospective pregnancy and birth cohort in Cincinnati, Ohio, USA. We examined the associations of average maternal OPE metabolite concentrations with OPE metabolite concentrations in childhood, characterized childhood OPE trajectories with latent class growth analysis (LCGA), and examined factors related to trajectory membership.
Results
Bis(2-chloroethyl) phosphate (BCEP) had the lowest median concentrations over time (0.66–0.97 mg/L) while the median concentrations of bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) increased with age (1.44–3.80 mg/L). The median concentrations of diphenyl phosphate (DPHP) fluctuated between 1.96 and 2.69 mg/L. Intraclass correlation coefficients for urinary metabolites measured at five time points indicated high variability within individuals (0.13–0.24). Average maternal urinary BCEP and BDCIPP were associated with concentrations in early childhood. Maternal education, the birth year of the child, and having a carpet in the main activity room were associated with BCEP and BDCIPP trajectory while none of the factors were associated with DPHP trajectory.
Significance
The trajectory analysis showed different patterns of urinary OPE metabolite concentrations, suggesting the need to collect multiple samples to adequately reflect OPE exposure.
Impact statement
In this well-established cohort, we evaluated the patterns of urinary OPE metabolites in children ages 1–8 years. The number of repeated measures over childhood has not been achieved in prior studies. Our results suggested the high variability of urinary OPE metabolites within individuals. Maternal metabolite concentrations during pregnancy were related to child concentrations at ages 1–3 years. BCEP, BDCIPP, and DPHP demonstrated different trajectories in children, which suggests that multiple samples may be required to capture OPE exposure patterns in childhood.
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Data availability
Data requests will be approved by the HOME Study Data Sharing Committee for research purposes.
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Acknowledgements
We gratefully acknowledged all the funding agencies and the contributions from all the study participants and staff. Joseph M. Braun was financially compensated for his services as an expert witness for plaintiffs in litigation related to PFAS-contaminated drinking water.
Funding
This work was supported by grants from the National Institute of Environmental Health Sciences and the US Environmental Protection Agency (NIEHS P01 ES11261, R01 ES014575, R01 ES020349, R01 ES027224, R01 ES028277, R21 ES034187, P30 ES006096; EPA P01 R829389).
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WY designed the work, contributed to the formal analysis, and drafted/revised the manuscript. JMB conceived the work and contributed to revising the manuscript and funding acquisition. AMV conceived the work, played an important role in interpreting the results, and revised the manuscript. ZP contributed to the formal analysis and revision of the manuscript. YX played an important role in data acquisition and result interpretation and revised the manuscript. CX contributed to the methodology and revision of the manuscript. RD conceived and supervised the work, and contributed to revising the manuscript. AMC contributed to data acquisition and revised the manuscript. MO contributed to data acquisition and revised the manuscript. KY conceived the work, revised the manuscript, and acquired funding. KMC conceived the work, revised the manuscript, and acquired funding. BPL: conceived the work, revised the manuscript, and acquired funding. AC: conceived and supervised the work, played an important role in data acquisition and result interpretation, revised the manuscript, and acquired funding.
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JMB was financially compensated for his services as an expert witness for plaintiffs in litigation related to PFAS-contaminated drinking water.
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The study protocol was approved by the Institutional Review Board (IRB) at Cincinnati Children’s Hospital Medical Center (CCHMC). The Centers for Disease Control and Prevention (CDC) deferred to the CCHMC IRB as the IRB of record.
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Yang, W., Braun, J.M., Vuong, A.M. et al. Patterns of urinary organophosphate ester metabolite trajectories in children: the HOME Study. J Expo Sci Environ Epidemiol 34, 251–259 (2024). https://doi.org/10.1038/s41370-023-00605-2
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DOI: https://doi.org/10.1038/s41370-023-00605-2