Geographic variation in groundwater iodine and iodine deficiency in Israel, the West Bank and Gaza

Background: Iodine deficiency during pregnancy and infancy is the world's most common preventable cause of mental retardation. Previous studies have shown a high incidence of goiter and low groundwater iodine concentrations in northern Israel. Objective: We examined the relationship between low groundwater iodine and iodine deficiency in pregnant women and schoolchildren. Subjects and Methods: We measured the urinary iodine excretion of school-children in the West Bank and Gaza and rural and urban pregnant women in Western Galilee (an area known to have low groundwater iodine concentrations). We also measured iodine concentrations in groundwater in various locations in the West Bank and Gaza. Results: Lower urinary iodine excretion was found among pregnant Arab women living in rural Western Galilee (101±7 μg iodine/g creatinine). 20% of them excreted <50 μg I/g creatinine. This is relatively less than found among pregnant Jewish women living in cities in the same area (154±13 μg I/g creatinine). Low iodine concentrations (<5 μg/l) were found in groundwater in the Nablus, Ramallah, Bethlehem highlands, as compared to normal concentrations in the lowland districts of the West Bank and Gaza. In a cohort of 728 schoolchildren aged 8-10, 10% (range 8-13%) of children from areas of low groundwater iodine had low levels of urinary iodine excretion, as compared to only <5% of those from districts with groundwater iodine concentrations >10 χ/l. Conclusions: Lower concentrations of groundwater iodine are related to low urinary iodine excretion in Israel, the West Bank and Gaza.