Wed May 18 15:38:07 CDT 2011
various locations in the region, and overall they took radiation
readings from more than 5,000 people, starting with the first team,
which surveyed nearly 1,000 residents.
The teams also recorded their own external exposures, using personal dosime=
Kashiwakura and colleagues found:
- Only 10 people had high values, but all were less than 100
kilocounts per minute on a Geiger-M=FCller survey meter, which is the
level at which decontamination is required.
- Most people surveyed had readings of less than 13 kilocounts per
minute, meaning no action had to be taken.
- The first team had elevated cumulative external exposures, reaching
nearly 100 microsievert in one case, but the exposures dropped over
time and there was essentially no difference between the third and
- Internal radiation exposure of team members was later measured using
a whole-body counter at Hirosaki University; radiation was not
detected in any case.
- In the affected region, indoor air had one-tenth the radiation dose
of outdoor air.
Kashiwakura and colleagues reported that study of a number of "hot
spots" where radiation accumulated is continuing, as are measurements
of the absorbed dose rate in air and the state of radioactivity.
Those data will be needed, they argued, to assess "short- and
long-term health effects such as carcinogenesis or leukemia,
especially in fetuses and infants."
This study was supported by a Grant for Education Program for
Professionals in Radiation Emergency Medicine in Hirosaki University.
The journal said the authors have declared that no competing interests
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