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National Institute of Environmental Health Sciences

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Your Environment. Your Health.

Publication Detail

Title: A possible approach to improving the reproducibility of urinary concentrations of phthalate metabolites and phenols during pregnancy.

Authors: Yazdy, Mahsa M; Coull, Brent A; Gardiner, Joseph C; Aguiar, Andrea; Calafat, Antonia M; Xiaoyun Ye; Schantz, Susan L; Korrick, Susan A

Published In J Expo Sci Environ Epidemiol, (2018 Sep)

Abstract: In epidemiologic studies, classifying episodic exposures to chemicals with short half-lives, such as phthalates and phenols, is challenging. We assessed whether accounting for sources of variability unrelated to exposure pathways would improve the reproducibility of urine concentrations of select phthalate metabolites and phenols. In 2011, a subset of pregnant women (n = 19) enrolled in a prospective study provided first morning urine samples every 3-4 weeks between 16 and 36 weeks gestation. At the time of collection, we identified potential contributors to variations in urinary concentrations: weight gain, gestational age, time slept, time since awoke, time since last food/drink, and time since last void. We estimated intraclass correlation coefficients (ICCs) among repeat urine concentrations with and without adjustment for sources of variability using a random intercept linear mixed model. Concentrations of monoethyl phthalate, butyl, and propyl parabens were the most reproducible (ICCs: 0.68, 0.56, and 0.56, respectively). However, adjustment for potential sources of variability unrelated to exposure pathways did not materially improve reproducibility nor the ability of a single sample to predict exposure based on average biomarker concentrations across pregnancy. Future studies should carefully consider the exposure timeframe and the reliability of using biomarker concentrations from a single time point to represent exposures over pregnancy.

PubMed ID: 30018406 Exiting the NIEHS site

MeSH Terms: Adult; Biomarkers/urine*; Environmental Exposure/analysis*; Environmental Exposure/standards; Environmental Monitoring/methods; Environmental Monitoring/standards; Female; Humans; Illinois; Linear Models; Phenols/urine*; Phthalic Acids/urine*; Pregnancy; Pregnant Women; Prospective Studies; Reproducibility of Results; Surveys and Questionnaires; Young Adult

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