Association between perfluoroalkyl and polyfluoroalkyl substances and maternal thyroid-related hormones in pregnant women

Abstract

BackgroundExposure to perfluoroalkyl and polyfluoroalkyl substances (PFAS) during pregnancy might affect thyroid-related hormone levels in pregnant women. However, most previous studies focused on the effects of PFAS containing 8-10 carbon atoms, and few studies have estimated the associations between PFAS with longer carbon chain and thyroid-related hormone levels. ObjectiveTo examine the associations between PFAS exposure and thyroid-related hormones in pregnant women. MethodsThe present study was based on the Jiashan Birth Cohort from September 2016 to April 2018. We analyzed 13 PFAS in maternal blood samples (n=781) by high-performance liquid chromatography-tandem mass spectrometry, as well as total triiodothyronine (T3), total thyroxine (T4), free T3 (FT3), free T4 (FT4), thyroid stimulating hormone (TSH), thyroglobulin antibody (TG-Ab), and thyroid peroxidase antibody (TPOAb) by electrochemiluminescence immunoassay. PFAS were divided into three groups:low concentration, medium concentration and high concentration according to the tertile of their concentrations. We estimated the associations between PFAS concentrations and thyroid-related hormones in pregnant women by multiple linear regression. ResultsIn the multiple linear regression models, a change in perfluorododecanoic acid (PFDoA) concentrations from the low concentration group to the high concentration group was associated with a −0.10 (95%CI: −0.20, 0) nmol·L−1 change in T3, −0.15 (95%CI: −0.28, −0.02) pmol·L−1 change in FT3, and −3.02 (95%CI: −5.66, −0.39) pmol·L−1 change in FT4, respectively. A change in perfluorotridecanoic acid (PFTrDA) concentrations from the low concentration group to the high concentration group was associated with a −0.10 (95%CI: −0.20, 0) nmol·L−1 change in T3. Compared with the low concentration group, the concentration of T4 in the medium concentration group of perfluorohexane sulfonate (PFHxS) increased by 6.10 (95%CI: 0.44, 11.75) nmol·L−1. No statistically significant associations were found between PFAS and TSH concentration. The negative associations of PFAS with thyroid-related hormones were more pronounced in pregnant women with positive TG-Ab and/or TPOAb. ConclusionExposure to PFAS during pregnancy may affect thyroid-related hormone homeostasis in pregnant women, and the effect is stronger in TG-Ab and/or TPOAb-positive pregnant women.

Keywords

• perfluoroalkyl and polyfluoroalkyl substances
• pregnant woman
• birth cohort
• thyroid-related hormones