Exposure to Dioxin-like polychlorinated biphenyls during Pregnancy and fetal thyroid function; A mixture analysis

Area of Science:

• Environmental Health Sciences
• Endocrinology
• Toxicology

Background:

• Dioxin-like polychlorinated biphenyls (DL-PCBs) are known endocrine disruptors.
• The impact of maternal DL-PCB exposure on fetal thyroid hormone regulation is not well understood.
• Thyroid hormones are critical for fetal development.

Purpose of the Study:

• To investigate the association between prenatal DL-PCB exposure and thyroid hormone levels in umbilical cord blood.
• To evaluate the effects of specific DL-PCB congeners and their mixtures on fetal thyroid function.

Main Methods:

• A cohort of 2240 pregnant women in Shenyang, China (2022-2023) was studied.
• Umbilical cord blood levels of free thyroxine (T4), free triiodothyronine (T3), and thyroid-stimulating hormone (TSH) were measured.
• Serum DL-PCB congeners were analyzed using electro-chemiluminescence immunoassays.
• Statistical analyses included linear regression, quantile g-computation (g-comp), generalized weighted quantile sum (g-WQS) regression, and Bayesian Kernel Machine Regression (BKMR).

Main Results:

• Several DL-PCB congeners showed significant negative associations with umbilical T4 and TSH levels.
• Mixture analyses (g-comp, BKMR) indicated that DL-PCB exposure was associated with decreased T4 and TSH.
• PCB126 showed the strongest negative association with T4; PCB105 with T3; and multiple congeners with TSH.

Conclusions:

• Prenatal exposure to DL-PCBs may disrupt fetal thyroid hormone homeostasis.
• Findings highlight potential risks to fetal thyroid function from environmental DL-PCB contamination.
• Further research is needed to clarify the mechanisms and long-term implications.