Environmental phenol exposures in 6- to 12-week-old infants: The Infant Feeding and Early Development (IFED) study.

BACKGROUND: Exposure to phenols, endocrine-disrupting chemicals used in personal care and consumer products, is widespread. Data on infant exposures are limited despite heightened sensitivity to endocrine disruption during this developmental period. We aimed to describe distributions and predictors of urinary phenol concentrations among U.S. infants ages 6-12 weeks. METHODS: The Infant Feeding and Early Development (IFED) study is a prospective cohort study of healthy term infants enrolled during 2010-2013 in the Philadelphia region. We measured concentrations of seven phenols in 352 urine samples collected during the 6- or 8- and/or 12-week study visits from 199 infants. We used linear mixed models to estimate associations of maternal, sociodemographic, infant, and sample characteristics with natural-log transformed, creatinine-standardized phenol concentrations and present results as mean percent change from the reference level. RESULTS: Median concentrations (µg/L) were 311 for methylparaben, 10.3 for propylparaben, 3.6 for benzophenone-3, 2.1 for triclosan, 1.0 for 2,5-dichlorophenol, 0.7 for BPA, and 0.3 for 2,4-dichlorophenol. Geometric mean methylparaben concentrations were approximately 10 times higher than published estimates for U.S. children ages 3-5 and 6-11 years, while propylparaben concentrations were 3-4 times higher. Infants of Black mothers had higher concentrations of BPA (83%), methylparaben (121%), propylparaben (218%), and 2,5-dichorophenol (287%) and lower concentrations of benzophenone-3 (-77%) and triclosan (-53%) than infants of White mothers. Triclosan concentrations were higher in breastfed infants (176%) and lower in infants whose mothers had a high school education or less (-62%). Phenol concentrations were generally higher in summer samples. CONCLUSIONS: Widespread exposure to select environmental phenols among this cohort of healthy U.S. infants, including much higher paraben concentrations compared to those reported for U.S. children, supports the importance of expanding population-based biomonitoring programs to infants and toddlers. Future investigation of exposure sources is warranted to identify opportunities to minimize exposures during these sensitive periods of development.

A comparison of ultrasound-based testis volume with Prader orchidometry and stability of testis size relative to peers from birth to 28 weeks.

BACKGROUND: Testis volume, an indicator of the reproductive development during minipuberty, is commonly measured by Prader orchidometer, despite ultrasound being the gold standard. Data are lacking on the longitudinal relationship between these two measures and on the stability of boys' relative testis size across infancy. OBJECTIVES: To examine the relationship between ultrasound-based and orchidometer-based testis volume measurements and to assess the stability of relative testis size among individual boys in the study. MATERIALS AND METHODS: The Infant Feeding and Early Development study is a longitudinal cohort of healthy infants recruited from hospitals in the Philadelphia area during 2010-2013. We measured testis size from birth to 28 weeks in 147 infants using Prader orchidometry (nine study visits) and ultrasound (five study visits). We modeled testis growth, extracted predicted volumes for each boy on each day of the study, and ranked these volumes from smallest to largest. RESULTS: The average testis volume trajectory exhibited linear growth over the first 16 weeks followed by slower growth and then a plateau. Prader orchidometry overestimated testis size by almost 3-fold, compared to ultrasound. A range of ultrasound volumes corresponded to each bead size (e.g., bead size of 1 cm3 corresponded to an ultrasound-based volume between 0.11 and 0.87 cm3). Infants changed rankings of median of 22 positions (of 147) across the entire 6-month follow-up. Infants' ranks near birth were highly correlated with their ranks at the end of the study. DISCUSSION: Consistent with other studies, we found wide variability in testis size during infancy and that Prader orchidometry overestimates testis size. When compared to ultrasound, orchidometry only crudely estimates testis size in this age group. Ultrasound-based volumes generally showed stability in relative testis size across infancy. CONCLUSION: Accurate measurement of testis size is difficult using orchidometry in infants. This highlights the need for ultrasound for accurate measurement, with a one-time measurement likely sufficient to determine relative testis size across the first 6 months of infancy.

Environmental Phenols and Growth in Infancy: The Infant Feeding and Early Development Study.

CONTEXT: Higher mean and rapid increases in body mass index (BMI) during infancy are associated with subsequent obesity and may be influenced by exposure to endocrine-disrupting chemicals such as phenols. OBJECTIVE: In a prospective US-based cohort conducted 2010-2014, we investigated associations between environmental phenol exposures and BMI in 199 infants. METHODS: We measured seven urinary phenols at ages 6-8 and 12 weeks and assessed BMI z-score at up to 12 study visits between birth and 36 weeks. We examined individual and joint associations of averaged early infancy phenols with level of BMI z-score using mean differences (ß [95% confidence intervals (CI)]) and with BMI z-score trajectories using relative risk ratios (RR [95% CI]). RESULTS: Benzophenone-3, methyl and propyl paraben, and all phenols jointly were positively associated with higher mean BMI z-score (0.07 [-0.05, 0.18], 0.10 [-0.08, 0.27], 0.08 [-0.09, 0.25], 0.17 [-0.08, 0.43], respectively). Relative to a Stable trajectory, benzophenone-3, 2,4-dichlorophenol, 2,5-dichlorophenol, and all phenols jointly were positively associated with risk of a Rapid Increase trajectory (1.46 [0.89, 2.39], 1.33 [0.88, 2.01], 1.66 [1.03, 2.68], 1.41 [0.71, 2.84], respectively). CONCLUSION: Early phenol exposure was associated with a higher mean and rapid increase in BMI z-score across infancy, signaling potential long-term cardiometabolic consequences of exposure.