WASHINGTON - Though no Defense Department personnel or their families were exposed to radiation causing adverse health conditions following the nuclear accident in Japan last year, the department has established a registry to provide information to those who served in the stricken country.

The March 11, 2011, earthquake and subsequent tsunami off the coast of Japan caused extensive damage to the Fukushima nuclear power plant, and radiation leaked from the facility.

The Defense Department has established an Operation Tomodachi registry for the 70,000 U.S. service members, family members, DOD civilians and DOD contractors who were in Japan from March 12 to May 11, 2011, said Dr. Craig Postlewaite, DOD's director for force readiness and health assurance.

"The concept of a registry evolved very soon after the crisis in Japan," the doctor said in an interview with the Pentagon Channel and American Forces Press Service. "Initially, there was great emphasis placed on environmental monitoring, because we needed to monitor those levels to ensure that people weren't adversely affected during the crisis."

Commanders used the monitoring information to assess whether to evacuate personnel. The monitoring data, plus a policy that required the services to report daily precisely where every service member was, enabled the department to establish the registry, he said. "We then had the capability to provide information on estimated doses of radiation" for each person, Postlewaite said.

The Operation Tomodachi registry is being built in a secure database in which all personal information is protected. The dosage estimates cover 13 different shore-based locations, U.S. Navy ships located off the mainland of Japan and aircrews. It also incorporates about 4,000 U.S. responders who were issued radiation dosimeters. "The registry will be finished this calendar year," Postlewaite said.

In addition to the registry, DOD is building a companion website to the registry. Individuals cannot be identified on the website, but people can click on a map to determine the exposures in a specific prefecture, base or area for those who spent most of their time on mainland Japan in the timeframe the registry covers. The website also has information on radiation doses from a medical standpoint.

The doses and other information in the registry and on the website have been peer-reviewed and agree with information provided by national and international groups – including the World health organization and the International Atomic Energy Agency, said Dr. Paul Blake, a senior health physicist at the Defense Threat Reduction Agency at Fort Belvoir, Va. Blake also serves as the Operation Tomodachi co-chair for the dose assessment and recording working group.

The radiation release from the nuclear plant came in two types, the doctor said. "One was the shorter-lived radioactive iodines," Blake said. "If you inhale it or ingest it, it has the tendency to collect in your thyroid in your neck. We needed to look at the health risk associated with that."

The other health risk is radioactive cesium. "Cesium can have a half-life of 30 years, so it is still over there in Japan," he said.

So from a health risk viewpoint, DOD officials looked at a dose to the thyroid and a dose to the whole body, and "that's how we prepared the dose assessment for our shore facilities," he said.

"Both the thyroid and whole body doses are significantly lower than the occupational limits that the Nuclear Regulatory Commission provides for this country," he added.

What people were doing was as important as where they were, Blake said. "The Marines, for instance, did a lot of humanitarian efforts. When you are out there pushing hard and sweating, you are drinking a lot more water, [and] you are breathing a lot harder," he explained. "We needed to take into account radionuclides would enter the body at a faster rate than someone doing a more sedentary [job]."

Sex and age made a difference in the assessments also. Absorption of radionuclides changes depending on a person's gender and age.

Officials also are concerned about children. "They can be more sensitive, because they are still growing," Blake said. "Fortunately, our children were fairly far back from the actual source. The doses they received were safe."

The registry can be found online http://registry.csd.disa.mil/otr.