title: Impact of removing iodized salt on the iodine nutrition of children living in areas with variable iodine content in drinking water.
abstract: OBJECTIVE
  Excess iodine in drinking water has emerged as a public health issue in China. This study assesses the effectiveness of removing iodized salt on reducing the iodine excess in populations living in high-iodine areas and also to identify the threshold value for safe levels of iodine in water.
  
  
  METHODS
  Twelve villages from 5 cities of Hebei Province with iodine content in drinking water ranging from 39 to 313 µg/l were selected to compare the urinary iodine content of children aged 8-10 years before and after removing iodized salt from their diet.
  
  
  RESULTS
  For 3 villages where median water iodine content (MWIC) was below 110 µg/l, following the removal of iodized salt (the intervention), the median urinary iodine content (MUIC) reduced to under 300 µg/l decreasing from 365, 380, 351 to 247, 240, 281 µg/l, respectively. However, the MUIC in the 9 villages with MWIC above 110 µg/l remained higher than 300 µg/l. The children's MUIC correlated positively with the MWIC in the 12 villages (p ≤ 0.001). The linear regression equation after removing iodized salt was MUIC = 0.6761MWIC + 225.67, indicating that to keep the MUIC below 300 µg/l (the iodine excess threshold recommended by the WHO) requires the MWIC to be under 110 µg/l.
  
  
  CONCLUSIONS
  Removing iodized salt could only correct the iodine excess in the population living in the areas with MWIC below 110 µg/l. In the areas with water iodine above 110 µg/l, interventions should be focused on seeking water with lower iodine content. This study suggests a threshold value of 110 µg/l of iodine in drinking water to maintain a safe level of dietary iodine.
authors.affiliation: Hebei Province Center for Disease Prevention and Control, No. 97, Huai'an Donglu, P.O. Box 050021, Shijiazhuang City, Hebei Province, China, lsm6810@163.com.
authors.forename: Shengmin
authors.initials: S
authors.lastname: Lv
authors.forename: Yinglu
authors.initials: Y
authors.lastname: Zhao
authors.forename: Yanxia
authors.initials: Y
authors.lastname: Li
authors.forename: Yuchun
authors.initials: Y
authors.lastname: Wang
authors.forename: Hua
authors.initials: H
authors.lastname: Liu
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Jun
authors.initials: J
authors.lastname: Zhao
authors.forename: Shannon
authors.initials: S
authors.lastname: Rutherford
mesh_terms: D002648:Child; D002681:China; D060766:Drinking Water / Q000737:chemistry*; D006801:Humans; D007455:Iodine / Q000008:administration & dosage* / Q000032:analysis* / Q000652:urine; D016014:Linear Models; D009752:Nutritional Status; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage*
chemical_list: D060766:Drinking Water; D017673:Sodium Chloride, Dietary; C034024:iodized salt; D007455:Iodine