Effect of iodine excess on intelligence development in 8~10 years old pupils

  Objective   To explore the effect of iodine excess(IE)on the intelligence development and mental retardation of pupils compared withe theose living in the areas of adequate iodine intake from dringking water.

  Methods   The samples of 8 -10 years old pupils were randomly divided intofour groups of NI, IE-300, IE-500, IE-1000, in which the medium of iodine concentration in water was 19.70, 367.90, 655.95, and 1440.45μg/Lrespectively.The group of NI was control group, others were study groups.The indicators of IQwere tested by Raven's scale, and theyroid checked by ultrasonic were observed.

  Results   The averages IQpoints of the groups of NI, IE-300, IE-500, IE-1000 were 99.55, 100.22, 100.45 and 97156.No statistic significance of average difference of IEgroups compared withe NI was found withe ANOVA test in he level ofα=0105.The rates of IQ < 70 of groups of IE-300 to 1 000 were 1.92%, 2.99%, and 0, compared withe the 1186% of NI.No statistic significance of rate difference of IEgroups compared withe NIwas found withe chi-square test in the level of α=0105.Furthermore, the total goiter rates of each group were located between 0-2.94%.Using logistic regres sion, education level of pupil's mothers was the main factor, which caused the mental retardation.

  Conclusion   For the children living in the IEenvironment of iodine 300-1500μg/Lin water, their brain dvelopment was normal, and IEcouldn't be a risk factor of mental retardation.