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Does perchlorate in drinking water affect thyroid function in newborns or school-age children?
Insights
Perchlorate in drinking water did not suppress thyroid function in children or newborns, even at high levels. Study findings do not support concerns about perchlorate
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.
Abstract:
Perchlorate is known to suppress thyroid function by inhibiting uptake of iodide by the human thyroid at doses of 200 mg/day or greater. A study was conducted to investigate the potential effects of perchlorate in drinking water on thyroid function in newborns and school-age children. A total of 162 school-age children and 9784 newborns were studied in three proximate cities in northern Chile that have different concentrations of perchlorate in drinking water: Taltal (100 to 120 micrograms/L), Chañaral (5 to 7 micrograms/L), and Antofagasta (non-detectable: < 4 micrograms/L). Among schoolchildren, no difference was found in thyroid-stimulating hormone levels or goiter prevalence among lifelong residents of Taltal or Chañaral compared with those of Antofagasta, after adjusting for age, sex, and urinary iodine. No presumptive cases of congenital hypothyroidism were detected in Taltal or Chañaral; seven cases were detected in Antofagasta. Neonatal thyroid-stimulating hormone levels were significantly lower in Taltal compared with Antofagasta; this is opposite to the known pharmacological effect of perchlorate, and the magnitude of difference did not seem to be clinically significant. These findings do not support the hypothesis that perchlorate in drinking water at concentrations as high as 100 to 120 micrograms/L suppresses thyroid function in newborns or school-age children.