POTASSIUM IODIDE IN RADIATION EMERGENCIES
The U.S. Food and Drug Administration - Center for Drug Evaluation and Research (Last Updated: December 12, 2001) - Guidance  Potassium Iodide as a Thyroid Blocking Agent in Radiation Emergencies.
Recommended Doses of Potassium Iodide (KI) for different risk groups.

130-mg dose of KI for adults and adolescents (over 12 years).
65-mg  dose of KI for Children over 3 through 12 years.
32-mg  dose of KI for children over 1 month through 3 years.
16-mg  dose of KI for children from birth to 1 month.

Pregnant women should be given KI for their own protection and for that of the fetus, as iodine (whether stable or radioactive) readily crosses the placenta. However, because of the risk of blocking fetal thyroid function with excess stable iodine, repeat dosing with KI of pregnant women should be avoided.

Lactating females should be administered KI for their own protection, as for other yound adults, and potentially to reduce the radioiodine content of breast milk, but not as a means to deliver KI to infants, who should get their KI directly.

As for direct administration of KI, stable iodine as a component of breast milk may also pose a risk of hypothyroidism in nursing neonates. Therefore, repeat dosing with KI should be avoided in the lactating mother, except during continuing severe contamination.

THE PROTECTIVE EFFECT OF KI LASTS APPROXIMATELY 24 HOURS.

For optimal protection against inhaled radioiodines, KI should be administered before or immediately coincident with passage of the radioactive cloud, though KI may still have a substantial protective effect even if taken 3 or 4 hours after exposure. Furthermore, if the release of radioiodines into the atmosphere is protracted, then, of course, even delayed administration may reap benefits by reducing, if incompletely, the total radiation dose to the thyroid.

Prevention of thyroid intake of ingested radioiodines, once the plume has passed and radiation protection measures (including KI) are in place, is BEST ACCOMPLISHED BY FOOD CONTROL MEASURES AND NOT BY REPEATED ADMINISTRATION OF KI.

Because of radioactive decay, grain products and canned milk or vegetables from sources affected by radioactive fallout, if stored for weeks to months after production, pose no radiation risk. Thus, late KI prophylaxis at the time of consumption is not required.

As time is of the essence in optimal prophylaxis with KI, timely administration to the public is a critical consideration in planning the emergency response to a radiation accident and requires a ready supply of KI.

State and local governments choosing to incorporate KI into their emergency response plans may consider the option of predistribution of KI to those indidividuals who do not have a medical condition precluding its use.
In June 2000, Zanzonico and Becker reported that: "oral KI is an effective means of reducing thyroid irradiation from environmentally dispersed radioiodine but is effective only when administered within 2 days before to approximately 8 hours after radioiodine intake."
Dr. Bill would like to point out that there is 76.5% iodine in Potassium Iodide. So a 130 mg dose of KI translates into 100 mg of actual iodine.
The doses of KI recommended above will result in an adverse reaction rate of less than 1 in 10 million children and less than 1 in 1 million adults.

However, KI should not be used by people allergic to iodine and is contraindicated in people with past or present thyroid disease, kidney disease, or tuberculosis.
People on certain medications must also be monitored carefully when it comes to using KI.

Spironolactone (Aldactone), Tramterene (Dyrenium), Amiloride (Midamor),
and lithium-based medications are just a few meds that may make use of Potassium salts such as KI extremely hazardous. 
Dietary sources of iodine.
U.S. salt producers use potassium iodide at a level of 0.006% to 0.01% KI.

Using Morton Salt as an example - each 1/4 teaspoon serving of Morton Iodized Salt (1.5 gram weight) contains 130 micrograms of KI.

To achieve an intake of 130 milligrams of KI one would have to ingest 250 teaspoons or over 5 cups of iodized salt per day.

Sea Salt consumption would have to be over 33 kilograms a day.

Kelp Tablets like Solgar Kep Tablets would require 442 pills per day (225 micrograms iodine/pill.

The reader is warned never to take iodine, iodine tablets, tincture of iodine, or Povidone-iodine solutions as they are very poisonous.
Other links on this topic can be found at:
Testimony on Thyroid Exposure Received from Iodine-131 by Richard D. Klausner, M.D.
Thyroid Effects
Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb tests.
Dr. Bill credentials.
More info on Potassium Iodide .
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