@misc{oai:repo.qst.go.jp:00062524,
 author = {Chun, Yan Wang and Zhang, Wei and Minamihisamatsu, Masako and Deqing, Chen and Morishima, Hiroshige and Yongling, Yuan and Luxin, Wei and Sugahara, Tsutomu and Hayata, Isamu and et.al and 王 春燕 and 張 偉 and 南久松 眞子 and 早田 勇},
 month = {Feb},
 note = {In order to learn the health effect of very low dose radiation, we analyzed chromosomes of lymphocytes of the residents in a high background radiation area (HBRA) and a control area (CA) in the south of China and in Beijing (T.Jiang et al, J.Radiat. Res. 2000; W. Zhang et al. J. Radiat. Res. 2003; I.Hayata et. Al., Cytogenet. Genome Res. 2004; C. Wang et al., China Occupational Medicine, 2008).
Individual dose was measured with electric pocket dosimeter (Aloka PDM-10) for 24 hours and/or thermoluminescence dosimeter (National UD-200S) for 2 months.  The level of natural radiation (gamma rays) in HBRA was 3 to 5 times higher than that in CA and Beijing. 
Cultures were set up within 8 hours after taking blood. Colcemid was supplemented in cultures from the beginning to the end for 48 hours. Chromosome preparations were made according to the high yield chromosome preparation method. Air-dry slides were stained with Giemsa or with fluorescent dyes using whole chromosome painting probes for Nos.1, 2, and 4.
Unstable types of chromosome aberrations (dicentrics and rings) were examined in 22 members of 8 families in HBRA and 17 members of 5 families in CA. From each family 3 generations participated in this study. On average 2,600 cells per subject were analyzed. Twenty-seven elders and 6 children in HBRA, 25 elders and 8 children in CA and 38 elders in Beijingg were examined with respect to stable types, i.e., translocations. On average over 4,297 cells per subject were examined. 
Increase of dicentrics and rings was observed in HBRA where the dose rate was lower than one cGy per year. This dose rate is the condition that less than one track of radiation passes through one cell in two months. The chromosome aberrations must be induced by a single track of radiation. There seems to be no threshold dose for the induction of chromosome aberrations. In case of translocations, the frequencies were much higher than that of dicentrics and rings both in HBRA and in CA. Statistically there was no difference in the frequencies of translocations between HBRA and CA, but the frequencies in children were lower than those in elders in both groups. The frequency in Beijing was similar to that in HBRA in elders. Individual variation was small in children while that in elders was large. 
Chromosome aberrations induced by the radiation at the dose rate 3 to 5 times higher than that in the control are within the range of individual variation of total chromosome aberrations which are caused by all kinds of mutagenic factors, such as chemicals, radiation, and metabolic factors in the normal living conditions., NIRS International Symposium on the Effects of Low Dose Radiation},
 title = {Chromosome Study on the Residents in High Natural Background Radiation Area and Control Area in the South of China and in Beijing},
 year = {2008}
}