Infantile phthalate metabolism and toxico/pharmacokinetic implications within the first year of life

Background: Infantile development of phthalate metabolism is crucial for risk assessment of endocrine disruption and has important toxico/pharmacokinetic implications. Objectives: To characterize temporal variability in urinary phthalate metabolites in infants and to examine their growth-dependent detoxification. Methods: In this cohort study, urine samples (n = 876) from 155 healthy Chinese infants were collected serially at eight time points from birth to one year old. Free and total (i.e., free plus glucuronide conjugated) phthalate metabolites (PMEs) were measured by LC/MS/MS. Time variability in PMEs and PME metabolism capacity was characterized using intraclass correlation coefficients (ICCs) and linear mixed regression models. Results: Concentrations of most PMEs changed significantly, with ICCs ranging from 0.213 to 0.318, and trends increased significantly over time (p