Article Title

Effects of drinking water with high iodine concentration on the intelligence of children in Tianjin, China


Objective: This study aimed to investigate the effects of drinking water with high concentrations of iodine on the intelligence of children in Tianjin, China.

Methods: It was a population-based health survey utilizing a random cluster sampling design conducted in June 2005. Participants were recruited from the total population of primary school children attending years 1–4 with ages ranging from 8 to 10 years. Intelligence quotient (IQ) was assessed using the combined Raven's test, second edition. Linear regression analyses were applied to test for any association between water iodine concentration and IQ.

Results: A total of 1229 students were recruited with a mean IQ of 105.8 (95% CI: 104.2–107.3). Water analyses indicated iodine concentrations were high in one rural region and exceedingly high in another with median values of 137.5 and 234.7 µg/l, respectively. There was a significant association between residing in the very high water iodine region and a reduction of IQ by an average of about nine points (P = 0.022), after adjusting for the potential confounding factors.

Conclusion: Exposure to high iodine concentrations in drinking water has detrimental effects on the intelligence of children.


peer-reviewed, epidemiology

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