Dose-effect Relationship of Dicentric and Ring Chromosomes in Lymphocytes of Individuals Living in the High Background Radiation Areas in China

Abstract

Chromosomes of 39 healthy family members (3 generations from 13 families) living both in the high-level background radiation areas (HBRA) and the control areas (CA) were studied. Cumulative dose from birth to the time of blood sampling was estimated by calculating measured exposure rate in each individual. The cumulative doses ranged 30.9-358.9 and 6.0-59.2 mGy for HBRA and CA, respectively. Peripheral lymphocyte chromosome preparations were made according to our improved method. Dicentric and ring chromosomes (Dic + Rc) were scored in average 2,527 cells per individual in HBRA and 2,694 cells in CA under a microscope equipped with an automated stage. A positive correlation between Dic + Rc and age was found in HBRA, while no such dose relationship was clear in CA. The frequency of Dic + Rc linearly increases over lifetime due to chronic low dose exposure and it is likely that the activation of repair enzymes is not triggered in the present HBRA. Threshold dose (rate) of the induction of chromosome aberrations, if any, is below the present dose (rate) level.

Chromosome aberrations in peripheral blood lymphocytes of individuals living in high background radiation areas of Ramsar, Iran

“…This controversy exists in studies of residents in areas with elevated levels of natural radiation as well as in residents of areas contaminated by nuclear accidents (Mortazavi and Karam 2005). Jiang et al (2000) showed a correlation between the incidence of total structural chromosome-type aberrations and accumulated doses, both in the high level natural radiation area and in control groups. The relationship between chromosome aberrations and increasing age was similar to that between chromosome aberrations and the accumulated dose.…”

“…There are some reports that exposure to elevated levels of natural radiation in these areas of Ramsar does not result in increased chromosomal damage and is not detrimental to the health of residents of these areas (Ghiassi-Nejad et al 2002;Mortazavi et al 2006). It is evident that if anything meaningful is to be identified in people exposed to low levels of radiation, a large number of cells should be examined (Jiang et al 2000). Thus, it is possible to detect the effect of an elevated dose level of natural radiation providing that a reasonably large number (at least 1,000) of cells per individual are analyzed.…”

Summary of biological studies

“…The health effect study on the inhabitants in the high background radiation area (HBRA) is one of informative approaches to resolve this issue [1,2]. Wang et al (China) demonstrated the results of their chromosome study in the HBRA in South China.…”

Mineral Radioactivity in Sands as a Mechanism for Fixation of Organic Carbon on the Early Earth

“…Nevertheless, such sands are capable of inducing changes on a relatively short time scale, as evidenced by an increased incidence of chromosomal abnormalities in human populations living in the vicinity of monazite beach sands in China (Jiang et al, 2000) and India (Forster et al, 2002). This effect is a consequence of emanated, dispersed radon, so an even briefer response time is expected for organic molecules in direct contact with the grains, and it is feasible that at least the first layers of molecules to accrete on the grains did so on the beaches of early Earth.…”