Chromosome study in high background radiation area in Southern China

We have studied the chromosomes of lymphocytes of the residents in a high background radiation area (HBRA) and a control area (CA) in the southern China. The level of natural radiation in HBRA is three to five times higher than that in control area. Unstable type aberrations (dicentrics and rings) were analyzed in 22 individuals in HBRA and 17 individuals in CA. Stable type aberrations (translocations) were examined in 28 elderly individuals and 6 children in HBRA and 24 elderly individuals and 8 children in CA. There was statistically significant difference in the increasing rates between those two areas in adult. In case of stable aberrations, the frequencies were much higher than those of the unstable aberrations both in HBRA and in control. Statistically, there was no difference in the frequencies between HBRA and CA, but the frequencies in children were lower than those in elderly individuals in both groups. Individual variation was small in children while that in adults was large. The amount of chromosome aberrations induced by radiation is not significant when it is compared with that induced by other mutagenic factors such as smoking in the Southern China.