Tracking the Radiation

The two radionuclides of concern were radioiodine and radiocesium. The former has a very short half-life (eight days), but cesium has a half-life of 30 years.

During the relief operation, however, DoD was able to directly monitor 8,380 serviceberry plants for radiation levels. Very little detectable activity was discovered.Of those monitored, 98% were below baseline, and the 2% who were above baseline had a maximum of 25 millirems (mrem)equivalent to about 2.5 chest X-rays.

U.S. Navy Petty Officer 2nd Class Robert Bannister removed mud sediment from behind a damaged building in Hachinohe, Japan, March 17, 2011. Sailors from Naval Air Facility Misawa and its tenant commands were assisting with cleaning up the tsunami-damaged city. Photo by Petty Officr 2nd Class Devon Dow, US Navy.

The radiation levels came down dramatically after the first month, plateauing and creating a new background level of radiation in Japan. Where before the background level was 105 mrem per year, that level is now around 170 mrem per year. This is still much lower than the U.S. population’s  average background radiation exposure, which is 310 mrem annually — most of which comes from radon exposure and cosmic radiation, excluding medical exposures.

Pointing out the many incidences where environmental exposure has led to health concerns for servicemembers later in life, Congress has directed DoD to create a database of servicemembers and their beneficiaries who could have even the smallest chance of exposure.

As a result, when the majority of Operation Tomodachi was winding down, the office of Craig Postlewaite, MD, DoD’s deputy director of force health protection and readiness, was just beginning its work in earnest.

All evidence suggested there had not been enough radiation exposure to create health effects, but DoD officials realized that any amount of reasonable doubt could lead to fingerpointing in the future.

“We knew that the first woman who gave birth to a child with a birth defect — this incident would be claimed to be responsible,” Postlewaite said. “We knew the database needed to withstand scrutiny, whether by Congress or watchdog agencies. We had to do this right.”

Most of DoD’s population was at least 150 miles from the reactor accident, and the wind at the time was primarily westerly, which meant that it was blowing away from the major U.S. installations.

Airborne radiation monitoring occurred at most of those installations and the major U.S. ships at sea. Individuals who actually had performed duties in the hot zone had been identified and could be tracked.

“We had a very effective accountability system,” Postlewaite said. “Most individuals [about 70-75% of DoD personnel] can be associated with a predominant location.”

The goal of the Operation Tomodachi Registry is to make it as comprehensive as possible in order to answer any questions that might be asked. This means including data on who was affected and where they were at the time, individual radiation data, ambient radiation exposure data and medical record data.

The registry will be used for medical treatment and diagnosis, inquires and exposure-related allegations, epidemiological health outcomes studies, medical surveillance and claims adjudication.

The first phase of the registry is scheduled to be completed this month. This is the dose assessment and recording phase — the creation of location-based radiation dose estimates for land-based population centers.

The second phase of the registry, which would have individual dose estimates completed for all individuals with personal dosimetry and internal monitoring data, is set to be complete in December 2012.

Much of this information, though not personal medical data, will be available online. DoD is constructing a public website that should be up sometime this month, Postlewaite said. “We’re making it in such a way to accommodate future exposure registries that may come to pass.”

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