Maternal Urinary Triclosan Concentration in Relation to Maternal and Neonatal Thyroid Hormone Levels: A Prospective Study

BACKGROUND: Triclosan (TCS) is a synthetic antibacterial chemical widely used in personal care products. TCS exposure has been associated with decreased thyroid hormone levels in animals, but human studies are scarce and controversial. OBJECTIVE: We evaluated the association between maternal TCS exposure and thyroid hormone levels of mothers and newborns. METHODS: TCS was measured by high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) in urine samples collected during gestational weeks [Formula: see text] from 398 pregnant women in a prospective birth cohort enrolled in 2012–2013 in Shanghai, China. Maternal serum levels of free thyroxine (FT(4)), thyroid-stimulating hormone (TSH), and thyroid peroxidase antibody (TPOAb) were obtained from medical records. Cord blood levels of free triiodothyronine (FT(3)), FT(4), TSH, and TPOAb were measured. Multiple linear and logistic regression models were used to examine the relationship between maternal urinary TCS and thyroid hormone levels. RESULTS: TCS was detectable ([Formula: see text]) in 98.24% of maternal urine samples with tertile of urinary TCS levels: low ([Formula: see text]), medium ([Formula: see text]), and high ([Formula: see text]). With adjustment for potential confounders, cord blood log(FT(3))pmol/L concentration was 0.11 lower in newborns of mothers with medium and high urinary TCS levels compared with those with low levels. At third trimester, the high TCS concentration was associated with 0.03 [95% confidence interval (CI) [Formula: see text] , [Formula: see text]] lower maternal serum log(FT(4))pmol/L, whereas the medium TCS concentration was associated with 0.15 (95% CI: [Formula: see text] , [Formula: see text]) lower serum log(TSH)mIU/L with adjustment for covariates. CONCLUSIONS: Our results suggest significant inverse associations between maternal urinary TCS and cord blood FT(3) as well as maternal blood FT(4) concentrations at third trimester. https://doi.org/10.1289/EHP500