Early-life exposures to phenols, parabens and phthalates and fat mass at 3 years of age in the SEPAGES cohort

Early-life exposure to short half-life chemicals may influence adiposity growth, a precursor to obesity. Previous studies often relied on limited urine samples that inadequately represent exposure during pregnancy or infancy. Additionally, childhood adiposity is commonly estimated using body mass index, which does not accurately reflect body composition. We aimed to investigate associations between early-life exposures to phenols, parabens, phthalates and fat mass percent at 3 years of age among 341 mother-child couple from the SEPAGES cohort. We further assessed potential effect modification by sex. We measured 8 phenols, 4 parabens, 13 phthalates and 2 non-phthalate plasticizer metabolites from weekly pooled urine sample collected from mothers during pregnancy (three urine samples a day, median 18 and 34 gestational weeks), and from their infant (one urine sample a day, at 2 and 12 months). Clinical examinations at 3 years included standardized skinfold thickness measurements and bioelectrical impedance analysis to calculate fat mass percentage. Positive associations were identified between prenatal exposures to bisphenol S, mono-benzyl phthalate (MBzP), monoethyl phthalate (MEP), and mono-n-butyl phthalate and fat mass percentage at 3 years, while triclosan showed a negative association. MBzP and MEP showed effect modification by sex, with stronger associations among females. No significant associations were detected for postnatal exposures. This study suggests associations between prenatal exposures to short half-life chemicals and percent fat mass in preschool children. Furthermore, this study is the first investigating the impact of prenatal bisphenol S exposure, highlighting the need for investigation of this overlooked compound.