Does perchlorate in drinking water affect thyroid function in newborns or school-age children?

Area of Science:

• Environmental Health
• Endocrinology
• Public Health

Background:

• Perchlorate is known to inhibit iodide uptake by the thyroid gland.
• Previous studies indicate thyroid suppression at doses of 200 mg/day or greater.
• The impact of perchlorate in drinking water on thyroid function in children is not well-established.

Purpose of the Study:

• To investigate the effects of varying perchlorate concentrations in drinking water on thyroid function in newborns and school-age children.
• To assess thyroid-stimulating hormone (TSH) levels and goiter prevalence in relation to perchlorate exposure.
• To evaluate the risk of congenital hypothyroidism in areas with different perchlorate levels.

Main Methods:

• A cross-sectional study involving 162 school-age children and 9784 newborns in three Chilean cities with distinct perchlorate levels (Taltal: 100-120 µg/L, Chañaral: 5-7 µg/L, Antofagasta: <4 µg/L).
• Adjusted analysis for age, sex, and urinary iodine levels.
• Monitoring of thyroid-stimulating hormone (TSH) levels and assessment of goiter prevalence and congenital hypothyroidism cases.

Main Results:

• No significant differences in TSH levels or goiter prevalence were observed among schoolchildren residing in Taltal or Chañaral compared to Antofagasta.
• No presumptive cases of congenital hypothyroidism were detected in Taltal or Chañaral, while seven cases were identified in Antofagasta.
• Neonatal TSH levels were lower in Taltal compared to Antofagasta, an unexpected finding not considered clinically significant.

Conclusions:

• Drinking water perchlorate concentrations up to 100-120 µg/L do not appear to suppress thyroid function in newborns or school-age children.
• The study does not support the hypothesis that environmental perchlorate exposure at these levels poses a risk to thyroid health in pediatric populations.
• Further research may be warranted to explore the unexpected lower TSH levels observed in newborns in Taltal.