Radiation Dispersal from Fukushima, Japan: Civilian Aircrew Recommendations

Civilian Crewmembers Operating on Flights between the US and Japan: Radiation Basics and Recommendations on Use of Potassium Iodide (KI)

Top level messages

  • Civilian crewmembers operating on flights between the US and Japan are not at risk of inhaling Iodine-131 under current circumstances
  • CDC does not recommend the use of KI by US civilian crewmembers at this time
  • While on the ground, aircrews are encouraged to register with and be in contact with the US Embassy in Tokyo (provide contact information)


Radioactive materials are substances (usually solids or liquids, but sometimes gases) that release energy. The energy released from radioactive materials is called radiation. Radioactive materials can be natural (for example, some rocks in the earth are radioactive) or man-made. When radioactive materials get on the body or inside the body, scientists call this contamination.

As a result of the ongoing emergency at the Fukushima Dai-ichi nuclear power plant, radioactive material has been found in several locations. Most of the radioactive material that has been released is in the immediate vicinity of the damaged power plant. One example of radioactive material that has been found is Iodine-131 (I-131).

I-131 released into the air can be breathed into the lungs (inhaled). It can also contaminate food. If inhaled or swallowed, I-131 may be quickly taken up by the thyroid where the energy (radiation) it releases can injure the gland. Taking potassium iodide (KI) can help prevent thyroid injury from occurring by blocking the uptake of radioactive iodine into the gland for about 24 hours. If a large amount of I-131 is inhaled or swallowed, it may take longer than 24 hours to clear from the body and more than one dose of KI may be necessary.

Based on current conditions in Japan, the use of KI is indicated only for those personnel working in and around the damaged nuclear power plant. This includes radiation plant workers and other workers assisting in the repair, restoration, monitoring, or other activities close to the damaged power station. They are the people at highest risk for thyroid gland injury.

Civilian crewmembers operating on flights between the U.S. and Japan are not at risk of inhaling I-131 under current circumstances. The Japan Civil Aviation Authority (CAA) has established flight restrictions to reroute civil aviation flights away from the damaged plant. Japan CAA has also been working cooperatively with the aviation industry to accommodate requests for flight routes even further away from the plant than what is required by the current flight restrictions. The FAA is prepared to work with the Japanese CAA to identify potential hazards to civil aviation and to take all necessary measures to protect civil aviation should the situation in Japan worsen.

While on the ground in Japan, aircrews are encouraged to register with and be in contact with the U.S. Embassy in Tokyo. The Embassy will have the most accurate and current information for Americans in Japan concerning the status of their food and water. The Department of State updated its Travel Warning for Japan on March 21, 2011. The Embassy is not advising Americans to take KI at this time. However, as a precaution, the Embassy is providing KI to its employees and their dependents who are permanently stationed in the areas specified in the Travel Warning, so that they have it on hand in case the situation changes. Also, as a precaution, the Embassy is making KI available to Americans with U.S. passports upon request.

CDC recommendations for Civilian Aircrews

CDC does not recommend the use of KI by U.S. civilian crewmembers at this time.

Precautions when considering use of KI

Use of KI may have adverse health effects in some persons. Therefore, KI should not be taken unless under the instructions of your healthcare professional or public health authorities. Individuals with known iodine sensitivity, dermatitis herpetiformis, hypocomplementemic vasculitis, or nodular thyroids with heart disease should avoid KI. Note that a seafood or shellfish allergy does not necessarily mean that you are allergic or hypersensitive to iodine. Individuals with multinodular goiter, Graves’ disease, and autoimmune thyroiditis should be treated with caution — especially if dosing extends beyond a few days.

If you are not sure if you should take KI, consult your healthcare professional.

CDC KI emergency use information source


FDA KI emergency use information sources

The FDA provides guidance on when and how much KI to take in radiation emergencies involving radioactive iodine.

Guidances/ucm080546.pdf pdf iconexternal icon

Guidances/ucm080542.pdfpdf iconexternal icon

The Department of State Travel Warnings for Japan, March 21, 2011 http://travel.state.gov/travel/cis_pa_tw/tw/tw_5398.htmlexternal icon

Page last reviewed: April 18, 2011