Endocrine Disruptors and Thyroid Health.

Area of Science:

• Environmental Health
• Endocrinology
• Toxicology

Background:

• Thyroidal endocrine-disrupting chemicals (EDCs) are widespread, with numerous sources including water, air, pesticides, and consumer products.
• Exposure to these chemicals is common, and many EDCs remain unidentified, complicating health risk assessments.
• Thyroid hormone is crucial for early brain development, making pregnant women and infants especially vulnerable to thyroid disruption.

Purpose of the Study:

• To review the sources, mechanisms, and health implications of thyroidal EDCs.
• To highlight the challenges in understanding EDC health effects due to co-exposures and uncharacterized chemicals.
• To emphasize the need for advanced methods to assess EDC mixtures and neurodevelopmental impacts.

Main Methods:

• Literature review of identified thyroidal EDCs and their exposure pathways.
• Analysis of the impact of EDCs on thyroid hormone synthesis, transport, metabolism, and action.
• Discussion of vulnerable populations and factors exacerbating EDC effects.

Main Results:

• EDCs interfere with thyroid hormone pathways through various mechanisms.
• Vulnerability to thyroid disruption is increased in pregnant women, infants, iodine-deficient individuals, and those with thyroid autoimmunity or specific genetic mutations.
• Health disparities may be worsened by differential EDC exposures.

Conclusions:

• Advanced methods, including high-throughput assays and in silico approaches for EDC mixtures, are essential for accurate risk assessment.
• Development of methods to detect EDC effects on neurodevelopment is critical.
• While personal precautions help, regulatory action on manufacturing and drinking water is necessary for population-level protection.