In the wake of Japan's disaster, many of us have spent some time considering the dangers of radiation. Sales of potassium iodide, the main treatment for radiation exposure, have soared, even here in the United States. In 2004, the American Academy of Allergy, Asthma and Immunology put out a position statement on The Risk of Severe Allergic Reactions from the Use of Potassium Iodide for Radiation Emergencies. Here are some take-away points:

• Potassium iodide (KI) has been suggested for use in preventing the thyroid gland from uptaking radioactive iodide in the event of radiation exposure or potential exposure.

• When KI was used in Poland after Chernobyl, it reduced the expected rate of thyroid cancer.

• For the most part, KI is safe, and the benefits far exceed the risks.

• However, there are risks of allergic reactions to oral administration of KI in those who have an iodine sensitivity or allergic reactions to the substance.

• Radiocontrast media (RCM) containing organic iodine are sometimes responsible for adverse reactions. These types of reactions should not be construed as indicative of a KI allergy.

• Similarly, contact dermatitis caused by iodine-containing antibacterials applied topically does not confirm an iodine allergy. "Anaphylaxis to these preparations is exceedingly rare and not proven to be due to iodine."

• Iodine allergy and seafood allergies are sometimes confused because seafood tends to have high concentrations of iodine. However, "IgE antibody mediated seafood allergy has never been attributed to iodine, but rather to specific proteins in fish and shellfish."