POTASSIUM IODIDE IN RADIATION EMERGENCIES -                              page 2
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.

The Chernobyl reactor accident resulted in massive releases of I-131 and other radioiodines.

Approximately 4 years after the accident, a sharp increase in the incidence of thyroid cancer among children and adolescents in areas covered by the plume, was observed.
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.
The use of KI in Poland is often quoted when people refer to the FDA Guidance Report.

Facts:

Approximately 10.5 million children under age 16 and 7 million adults received at least one dose of KI.

The side effects among adults and children were generally mild and not clinically signifcant.

It is also notable that the thyroid radiation exposures after Chernobyl were virtually all internal, from radioiodines.

Despite some degree of uncertainty in the doses received, it is reasonable to conclude that the contribution of external radiation was negligible for most individuals.

THE INCREASE IN THYROID CANCER SEEN AFTER CHERNOBYL IS ATTRIBUTABLE TO INGESTED OR INHALED RADIOIODINES.

THIS POTENTIAL HAZARD HIGHLIGHTS THE VALUE OF AVERTING SUCH RISK BY USING KI AS AN ADJUNCT TO EVACUATION, SHELTERING, AND CONTROL OF CONTAMINATED FOODSTUFFS.

The protective effect of KI lasts approximately 24 hours.

It is also important to note that KI will not "wash" radioactive iodine from the thyroid gland.
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