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 6. Logistics of stable iodine prophylaxis 
       6.1 Chemical form 
       Stable iodine can be used either as potassium iodide (KI) or potassium 
      iodate (KIO3). KI is the preferred alternative, since KIO3 has the 
      disadvantage of being a stronger intestinal irritant (19). There is 
      no decisive difference in shelf life between KIO3 and KI. If storage 
      conditions are adequate, the expected shelf life of the tablets is at 
      least 5 years. After 5 years the iodine content may be checked and the 
      shelf life extended, if indicated. 
       6.2 Formulation, storage and packaging 
       Stable iodine can be given in either doubly scored tablet or liquid 
      form. Tablets have the advantage of easy storage and distribution, 
      including predistribution. Also, stable iodine is likely to cause less 
      gastrointestinal irritation if administered in tablet form. Tablets can be 
      crushed and mixed with fruit juice, jam, milk or similar substance. 
       Tablets should be stored protected from air, heat, light and moisture. 
      Age-dependent dosage and contraindications should be on the labelling. 
       Tablets packed in a hermetic alufoil and kept in a dry and cool place 
      preserve fully their iodine content for 5 years (20). 
       6.3 Availability, predistribution and distribution 
       As there is only limited time for implementation of prophylaxis, prompt 
      availability of the tablets to individuals has to be ensured if they are 
      to be at their most effective. In the vicinity of nuclear reactors, 
      predistribution to households should be seriously considered, taking into 
      account plans for evacuation and sheltering, with provision for storage in 
      places that can be controlled by the responsible authorities. Clear 
      instructions should be issued with the tablets, and public awareness of 
      the procedures should be monitored on a regular basis. Medical personnel 
      likely to be consulted by the public should be provided with more detailed 
      information. At greater distances from the site of release there is likely 
      to be more time for decision-making. If predistribution to households is 
      not considered feasible, stocks of stable iodine should be stored 
      strategically at points that may include schools, hospitals, pharmacies, 
      fire stations, police stations and civil defence centres. Widespread 
      storage may be warranted at considerable distances from the potential 
      accident site. Storage should preferably be at places where proper stock 
      control is standard practice. Planning should consider the use of 
      redundant distribution areas to minimize delays in implementing stable 
      iodine prophylaxis. Due consideration should also be given to whether the 
      benefits of stable iodine distribution outweigh the disadvantages 
      associated with any additional exposure of responsible emergency 
      personnel. 
       National authorities are advised that, because of the benefits of 
      stable iodine prophylaxis and the generally minimal risks of side effects, 
      voluntary purchase of iodine tablets by the general public should be 
      allowed. However, within the framework of the overall nuclear emergency 
      plan, the responsibility for distribution of stable iodine and instructing 
      the public on how to use it should still be clearly assigned to the 
      appropriate authorities. 
       6.4 Dosage and contraindications 
       For adequate suppression, the dosage scheme given in Table 2, which is 
      based on a single dose for adults of 100 mg of iodine, is recommended. 
       The tablet divisions indicated in Table 2 are easy to achieve with a 
      tablet stamped by a cross, except that the exact dosage of 1/ 8 tablet 
      required for neonates is difficult to ensure. However, for neonates over 1 
      week of age living at home, an approximate division would be satisfactory. 
      The most sensitive group of the newborn, those less than 1 week old, 
      should preferably have a more exact dosage. This can be achieved with KI 
      solution freshly prepared from crystals. It is, therefore, recommended 
      that maternity wards keep KI in storage in crystal form. 
       As an alternative, tablets containing 50 mg of iodine (65 mg KI or 85 
      mg KIO3) can be used, correspondingly doubling the tablet dosage indicated 
      in Table 2. It is recognized that some iodine tablets are too small to 
      subdivide effectively and it is recommended that tablets of sufficient 
      size be manufactured. 
       The contraindications for use of stable iodine are: 
       · past or present thyroid disease (e. g. active hyperthyroidism) 
       · known iodine hypersensitivity 
       · dermatitis herpetiformis 
       · hypocomplementaemic vasculitis. 
       These should be clearly stated on the labelling. 
       6.5 Timing of administration and duration of prophylaxis 
       To obtain full effectiveness of stable iodine for thyroidal blocking 
      requires that it be administered shortly before exposure or as soon after 
      as possible. However, iodine uptake is blocked by 50% even after a delay 
      of several hours. Fig. 1 shows the effectiveness of thyroid blocking 
      achieved by administering stable iodine at different times before or after 
      a 4-h exposure to radioiodine. 
       To protect against inhaled radioactive iodine, a single dose of stable 
      iodine would generally be sufficient, as it gives adequate protection for 
      one day. This may well be enough to protect from inhaled radioactive 
      iodine present in a passing cloud. In the event of a prolonged release, 
      however, repeated doses might be indicated. 
       
       Fig. 1. Averted dose as a function of time stable iodine is 
      administered to a 4-h intake of 131 I for different dietary iodine intakes 
       [Note from KI4U: Unable to capture this graph to HTML for display 
      here. To view it with an Adobe Acrobat Reader, get the original PDF file 
      here Guidelines for Iodine Prophylaxis following Nuclear 
      Accidents. If you know how to capture this graphic in a form we can 
      then display here, too, please let us know. Thank you.] 
       In some circumstances stable iodine administration may also be 
      practical in limiting the dose to the thyroid from ingested radioactive 
      iodine, especially to children via the milk pathway where alternative 
      sources cannot be found. In that case, a daily dose of stable iodine may 
      be given for the time period needed to those children who show no adverse 
      reaction. Repeated administrations should not be given to neonates, or to 
      pregnant or lactating women (see section 3.2). 
       Due consideration should be given, in preparing emergency plans, to 
      mitigating any adverse psychosocial reactions to the implementation of 
      iodine prophylaxis. To avoid public concern, distribution and instructions 
      to different age groups must be orderly and consistent. There are 
      advantages in consulting with neighbouring countries with regard to their 
      national policy in order to avoid discrepancies of approach, especially 
      where reactors are close to national borders. 
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      Guidelines for Iodine Prophylaxis following Nuclear 
      Accidents
      
Update 1999, World Health Organization, Geneva
      
Guidelines for Iodine Prophylaxis following Nuclear 
Accidents
updated 1999 World Health Organization
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