Answer to Question #8040 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:

I may take a civilian contractor job on Kwajalein Atoll (Republic of the Marshall Islands) for 24 months. Is there presently an increased level of radiation due to the history of the island? And what year was the last nuclear burst?


Kwajalein is a very safe place to reside today in terms of exposure to residual radiation from nuclear testing conducted in the Marshall Islands. There are several important facts to support that statement.

First, Kwajalein is at a considerable distance from the nuclear test sites, about 700 km from Bikini and more than 1,000 km from Enewetak. Second, the last nuclear test in the Marshall Islands was in 1958. Even at locations close to the test sites, the radioactive decay that has taken place over the more than 50 years since the testing has diminished most of the radioactive elements to amounts that cannot be detected.

At Kwajalein, the deposition of fallout was not very great. One of my publications in Health Physics in 1997 shows that the amount of radioactive 137Cs on Kwajalein Island is about the same as that on other island locations in the mid-Pacific that received no fallout from the Marshall Islands, but only small amounts of radiation from global fallout, meaning that there is very little radioactivity there from the Marshall Islands nuclear tests. In addition, Kwajalein Island has very little original soil from those years. Today, much of the island is covered by concrete (see a photo on and other areas have been the sites of earthmoving and construction. This means that the very small amounts of fallout deposited there (50 years ago) have been likely buried by earthmoving activities.

Measuring bomb-test radiation today on Kwajalein is much more difficult than in almost any city you would choose in the continental United States. My expertise is in low-level radiation exposure and radiation health effects, and I would not have any hesitation, whatsoever, about residing on Kwajalein.

Steven L. Simon, PhD
Bethesda, MD

Answer posted on 20 January 2009. 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.