Neonatal thyroid function in Seveso 25 years after maternal exposure to dioxin

Area of Science:

• Environmental Health
• Endocrinology
• Toxicology

Background:

• Neonatal hypothyroidism is linked to environmental contaminants in animal models, but human evidence is inconsistent.
• 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a persistent environmental contaminant.
• The study investigates the association between maternal TCDD exposure and neonatal thyroid function.

Purpose of the Study:

• To evaluate the association between maternal exposure to 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and neonatal thyroid function.
• To assess the impact of TCDD on blood thyroid-stimulating hormone (b-TSH) levels in newborns.
• To examine the long-lasting effects of environmental contaminants on thyroid function.

Main Methods:

• A population-based study of 1,014 children born to women of reproductive age in contaminated zones (A and B) and a reference area.
• A biomarker study on 51 mother-child pairs with recent maternal plasma dioxin measurements.
• Measurement of neonatal blood thyroid-stimulating hormone (b-TSH) and statistical analyses adjusting for confounding factors.

Main Results:

• Mean neonatal b-TSH levels were significantly higher in contaminated zones (Zone B: 1.35 microU/ml, Zone A: 1.66 microU/ml) compared to the reference area (0.98 microU/ml).
• The proportion of children with elevated b-TSH (> 5 microU/ml) was significantly higher in Zone A (16.1%) and Zone B (4.9%) than in the reference area (2.8%).
• Neonatal b-TSH levels correlated positively with maternal plasma TCDD and plasma toxic equivalents of dioxin-like compounds.

Conclusions:

• Maternal exposure to dioxins, such as TCDD, can modify neonatal thyroid function.
• Environmental contaminants like dioxins exhibit long-lasting capabilities to alter thyroid function post-exposure.
• These findings highlight the potential public health impact of persistent environmental toxins on neonatal development.