Answer to Question #10993 Submitted to "Ask the Experts"

Category: Environmental and Background Radiation — Soil and Fallout

The following question was answered by an expert in the appropriate field:


As a young boy, I lived on the Kwajalein Atoll in the Marshall Islands in the late 1970s and early 1980s. I am now 43 years old and have been diagnosed with hyperthyroid, a condition my mother has also. I sent out a poll on a social media site and the feedback from prior residents is overwhelming—many people from the island have been diagnosed with thyroid problems. Could the radiation on Kwajalein Atoll in the late 1970s and early 1980s have caused my thyroid condition?


All information we have indicates it is extremely unlikely that radiation on Kwajalein Atoll in the late 1970s and early 1980s could have caused your thyroid condition. I base my statement on the following data.

Kwajalein is an atoll located more than 400 km from Bikini Atoll and over 600 km from Eniwetok Atoll where the nuclear testing was conducted.

Health Physics Journal 99(2) August 2010
Graphic used with permission. Health Physics Journal 99(2); August 2010.

Because these are large distances and because very little of the fallout from those tests traveled towards the more southerly located atolls, Kwajalein received little exposure from fallout. I can validate that statement because I personally monitored the radiation levels on every atoll in the Marshall Islands, including Kwajalein, during the years 1990–1995. My measurements, sponsored by the Marshall Islands Government, comprise the most comprehensive set of data in existence on radiation in the Marshall Islands. The radiation level on Kwajalein is extremely low and it is quite difficult to measure any radiation at all. Moreover, it is simple physics to extrapolate back to the 1970s (or to any year for that matter)—there was not enough exposure even in the years you lived there to substantially increase your risk of thyroid disease.

Also, remember that the last nuclear test in the Marshall Islands was in 1958, about 20 years before your residence on Kwajalein. The types of radioactive elements in fallout that expose the thyroid gland to any significant degree are short-lived, lasting only a few weeks. Hence, there is almost no chance whatsoever that radiation exposure from residual nuclear testing fallout was the cause of your disease.

The fact that you, and people you know from Kwajalein, have thyroid conditions reflects their common occurrence. Thyroid diseases of all types are very common and place a significant health burden on society today. You can read more for yourself from the National Thyroid Association about how frequent these conditions are at and more about hyperthyroidism and related conditions at

Steven L. Simon, PhD, National Cancer Institute, Bethesda, MD

Answer posted on 18 June 2014. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.