Urinary concentrations of eighteen environmental phenols and the associations with feeding pattern in infants in the first 6 months of life

Environmental phenols are a group of typical endocrine disruptors, and widely detectable in human breast milk and infant formulas. However, exposures data are scarce in early infancy, a particularly sensitive period to environmental pollutants exposures. We aimed to prospectively assess urinary concentrations of eighteen environmental phenols in infants from birth to 6 months of age and their associations with feeding patterns (breastfeeding, formula and mixed-feeding). This study included 197 mother-infant pairs. Urinary concentrations of six parabens (PBs), seven bisphenols, four benzophenones (BPs) and triclosan were measured in infants at the ages of 3 days, 42 days, 3 and 6 months by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Multivariable linear regression models were applied to evaluate the associations between infant feeding types and urinary phenol concentrations in log₁₀-transformed scale. The detection rates of bisphenol A and S, methyl 4-hydroxybenzoate (MeP), ethyl 4-hydroxybenzoate (EtP), and propyl 4-hydroxybenzoate (PrP) were persistently high (ranged 48.7%–100.0%) across all ages (3 days, 42 days, 3 and 6 months). The detection rates of bisphenol P, B and AP were high (ranged 76.9%–95.9%) at age 3 days, and lower (14.4%–88.0%) at later ages. Compared to exclusive breastfeeding, mixed feeding was associated with 0.32 (95% CI: 0.01, 0.62, p < 0.05) higher log (BPA) (μg/g creatinine) at 42 days, 0.69 (0.03, 1.35) higher log (TCS) (μg/g creatinine) at 3 months, 0.54 (0.08, 1.00) higher log (EtP) (μg/g creatinine) at 6 months; formula feeding was associated with 1.30 (0.59, 2.00) and 0.91 (0.22, 1.60) higher log (BPB) (μg/g creatinine) at the age of 42 days and 3 months respectively, 1.19 (0.003–2.37) higher log (BPP) and 0.95 (0.27–1.64) higher log (BPS) (μg/g creatinine) at 3 months. In conclusion, exposures to BPA and its analogs, and parabens (MeP, EtP, and PrP) were extensive in early postnatal life of infants. Breastfeeding might be a safer form of feeding for infants against exposure to some phenols.