Academic journal article Environmental Health Perspectives

Within-Day, Between-Day, and Between-Week Variability of Urinary Concentrations of Phenol Biomarkers in Pregnant Women

Academic journal article Environmental Health Perspectives

Within-Day, Between-Day, and Between-Week Variability of Urinary Concentrations of Phenol Biomarkers in Pregnant Women

Article excerpt

Introduction

Phenols include high-production-volume chemicals with widespread uses in daily life products. For example, bisphenols are employed in the manufacture of epoxy resins and certain polymer plastics used in food and beverage containers and in other consumer products (Chen et al. 2016; INERIS 2014; NTP 2008). Parabens are used as preservatives in cosmetics, food, beverages, and pharmaceuticals; benzophenone-3, an ultraviolet-filter, is used in plastics and cosmetics; triclosan is used for its antibacterial properties in personal care products, clothing, or kitchenware (Cosmetic Ingredient Review Expert Panel 2008; Krause et al. 2012; NLM 2016); 2,4-dichlorophenol is used in the production of certain pesticides; and 2,5-dichlorophenol is a major metabolite of 1,4-dichlorobenzene, which is used in moth balls and room deodorizers (Crinnion 2010; HSDB 2016).

Concern exists regarding the health effects of phenols, which are potential endocrine disruptors, particularly following exposure during fetal life (Braun 2017). In terms of study design, most biomarker-based studies in humans relied on biomarker concentrations assessed in very few (one to three) spot biospecimens per pregnant woman. For chemicals with strong within-subject temporal variations, relying on a small number of biospecimens is expected to imperfectly characterize the average exposure (e.g., over a day, a week or longer), to lead to exposure misclassification, and consequently bias dose-response functions (Carroll et al. 2006; Perrier et al. 2016). The biological half-life of phenols in pregnant women is not known and could strongly differ from that of nonpregnant women, for example, as is the case for urinary biomarkers of tobacco smoke exposure such as cotinine, which has been found to have about twice as fast elimination half-life during pregnancy compared with postpartum (Dempsey et al. 2002). Studies based on nonpregnant adults reported a short (<12-h) half-life for some phenols (Janjua et al. 2007; Sandborgh-Englund et al. 2006; Volkel et al. 2002). Consequently, the relevance of relying on one spot bio-specimen to provide a proxy of exposure for time windows of one day or longer is probably limited. This issue is of importance given the expected impact of exposure misclassification on bias in dose-response functions relating biomarker levels to health parameters (Perrier et al. 2016). Several studies evaluated the reproducibility of urinary phenol concentrations during pregnancy (Bertelsen et al. 2014; Braun et al. 2011, 2012; Guidry et al. 2015; Jusko et al. 2014; Meeker et al. 2013; Philippat et al. 2013; Smith et al. 2012; Stacy et al. 2017). These studies relied on generally two or three spot biospecimens collected from each pregnant woman several weeks or months apart. Such a design did not allow characterizing the within-day or the within-week variability in biomarkers concentrations. Based on complete urine collections throughout several days in eight nonpregnant participants, two studies reported high within-subject and between-day variability for bisphenol A (Koch et al. 2014; Ye et al. 2011), whereas this variability was relatively small for some parabens, triclosan, and benzophenone-3 (Koch et al. 2014). High within-day variability of bisphenol A concentrations was also reported in 66 pregnant women with complete urine collection during one or two days (Fisher et al. 2015). In the context of pregnancy, estimations of the within-subject variability of phenols other than bisphenol A are lacking.

Accurate description of the variability of phenol urinary concentrations during pregnancy is crucial for adopting biospecimens sampling strategies that limits exposure misclassification in etiological studies. Our aim was consequently to characterize the within-day, between-day (within a week), and between-week variability of urinary concentrations of 10 phenols in pregnant women.

Methods

Study Participants

This study relied on a subgroup of the feasibility study conducted between July 2012 and July 2013 in the planning of the SEPAGES cohort (Suivi de lExposition a la Pollution Atmospherique durant la Grossesse et Effets sur la Sante [Assessment of Air Pollution Exposure during Pregnancy and Effects on Health]). …

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