Prenatal Triclosan Exposure and Thyroid Hormones Measured at Birth

Abstract

Triclosan (TCS) is an antibacterial compound introduced in 1972 and used in personal care products including soaps, cosmetics, and toothpastes. It has been shown to disrupt thyroid pathways; thus, exposure among pregnant women is concerning, given the role of thyroid hormones in early brain development.Although TCS was banned by the U.S. Food and Drug Administration in 2016 in soaps, it is still present in toothpastes, deodorants, and shave gels. The literature is inconsistent on the association between TCS exposure and thyroid hormones. We analyzed the association between prenatal TCS exposure and Thyroxine (T4), Free Thyroxine (FT4) and Thyroid Stimulating Hormone (TSH), in cord blood from participants in a prospective cohort study in New York City.Women were enrolled into the Columbia Center for Children’s Environmental Health (CCCEH) cohort from 1998-2006. TCS was measured in a spot urine sample collected in the third trimester. Relevant covariates were assessed by questionnaire or medical records. Umbilical cord thyroid hormones were measured for T4, FT4, and TSH. Among N=165 women with both TCS and thyroid hormone measures available, we used linear regression to assess the effects of TCS on thyroid hormones.TCS was detected in 80.5% of CCCEH urine samples with a median concentration of 8.4 ng/mL, after adjusting for urinary dilution. We found significant negative associations between prenatal TCS exposure and T4 (β= -2.69, p=0.01) and TSH (β= -0.08, p=0.03). The associations were strengthened after removing women with planned caesarian sections and restricting to women who went through labor (N=146), T4 (β= -3.47, p=0.003) and TSH (β= -0.104, p=0.014).confirmed, the continued use of TCS should be re-evaluated.We found detectable concentrations of TCS among women who were pregnant before the U.S. FDA ban and significant associations between prenatal TCS and thyroid hormones measured in cord blood. Additional research is needed to confirm the associations.