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Tokai JCO Criticality Accident

Report [17]11/13/99 15:30

DNA Damage Found in Eight People by Secretive Analysis

According to Asahi and other newspapers, urine samples of area residents were analyzed for DNA damage without the knowledge of the residents or the officials of Tokai-mura where JCO plant is located. The samples were taken during health examinations carried out in early October by Ibaraki prefecture. Not only were the DNA analysis carried out secretively, but the results were not reported to the residents or the officials of Tokai-mura either.

According to official documents of Ibaraki prefecture, residents and employees with their work located within 500 meters radius of JCO plant who requested to have health examinations were examined at Tokai-mura community centers on October 2nd ~ 4th. The examinations consisted of consultation, blood-test, urine-test, and upon request, the measuring of external radiation exposure. (Radiation measurement by whole body counter necessary to determine internal exposure was never conducted.) The results of all these examinations were given to the residents and workers, however, the DNA analysis of the urine samples from this original examination was carried out without the knowledge of the ones examined or the Tokai-mura officials.

The Original Examination

Documents from Ibaraki prefecture reports as follows. All together 1838 people (812 males and 1026 females) were examined from October 2nd ~ 4th . Among them 1331 were from Tokai-mura, 281 from Naka-machi, a town next to Tokai-mura, and the rest were from other areas within 500 meters radius of the plant. All together 117 doctors, nurses, and other medical professionals carried out the examinations. Numbers of lymphocyte were measured to see if any harm was done by radiation. The results were put into five categories.

A: No abnormality

B1: The numbers of lymphocyte are a little low but there seems to be no harm done by radiation.

B2: The numbers of lymphocyte are low and a re-examination is recommended.

C: There is abnormality with items other than lymphocyte numbers, however, there is no harm from radiation

D: The numbers of lymphocyte are extremely low

# of people

# of people examined
 for lymphocyte numbers

result categories














The DNA Harm Analysis

Of the urine samples of people examined for lymphocyte numbers, Ibaraki prefecture had requested the urine samples of 150 people that were within 350 meters radius of the plant at the time of the accident to be examined for DNA damage. The samples were delivered to St. Marianna University School of Medicine in Kawasaki city and were examined by Dr. Hiroshi Yamauchi. The concentration of a substance called urinary 8-hydroxil 2-deoxyguanosine was measured and compared with the average of Japanese citizens which is 15.7nanogroms per 1mg creatinine. Higher than average amount of this substance indicates DNA damage. The result showed that 8 people had an amount higher than the upper-end (21.1nanograms) of the standard amount. The highest amount measured was 29.1nanograms. The doctor had first concluded that the figures were not high enough to be of any worries, however, considering that the progress of DNA damage increases five days after the accident, and the urine samples were taken 2 to 4 days after the accident, the doctor strongly urged Ibaraki prefectural government to re-examine the eight people. However, the prefecture asserted that “the reliability of this [DNA damage analysis] test is still unknown, and examination of lymphocyte numbers should be given priority.” and would not consent to consider re-examination. Furthermore, the prefecture did not inform the results to the eight people with higher than average amount of 8-hydroxil 2-deoxyguanosine because “the anxiety of residents will increase if the numbers are made public.” The JCO employees that were at the site at the time of the accident, and the 69 people officially reported as being exposed, were not include in the 150 people examined for DNA damage.


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