Cytogenetic studies for a group of people living in Japan 1 year after the Fukushima nuclear accident

In order to understand the potential health effect of radiation from Fukushima nuclear disaster, a group of people living in Japan during and after the accident were investigated 1 y after the accident. The venous blood samples were extracted in tune from 156 tested persons living in Tokyo and Niigata with average age of 42.4 +/- 10.2 y old as well as 87 controls living in Beijing with similar age and sex proportion. Conventional chromosome culture and cytochalasin B micronucleus methods were applied. The unstable chromosome aberrations of 200 cells and micronuclei (MN) and micronuclei cells (MNC) of 1000 binucleated lymphocytes were analysed for each examined subject. The results showed that the frequencies +/- SE (x100) of the dicentrics plus rings were 0.17 +/- 0.024 % and 0.13 +/- 0.028 % in the tested and control populations (p > 0.05), respectively. The frequencies of the extra acentrics were 0.21 +/- 0.026 % and 0.06 +/- 0.018 % in the tested and control groups (p < 0.01), respectively. The total chromosomal aberration frequencies of the tested and control groups were 0.40 +/- 0.036 % and 0.20 +/- 0.034 % (p < 0.01), respectively. The MN and MNC frequencies of the tested group were 29.25 +/- 3.96 aEuro degrees and 23.85 +/- 4.23 aEuro degrees, and 25.30 +/- 6.45 aEuro degrees and 21.56 +/- 3.99 aEuro degrees for control group (p < 0.01). With the exception of dicentrics, there were significant differences (p < 0.01) between two groups in frequencies of chromosome aberration and MN. Generally, 1 y after the Fukushima nuclear accident, the dicentric frequencies had not increased in the 156 persons investigated in this study. The increase in chromatid aberrations, chromosomal acentrics and MN was induced but could not be directly linked to radiation exposures, as an excess of dicentric frequency is linked. However, the observed higher frequency of chromosomal alterations might be related to exposure to the low doses of ionising in this cohort. Consequently, it is recommended to assess the long-term health effects in this population.