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- Brzozowska, Kinga, et al.
(författare)
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Effect of temperature during irradiation on the level of micronuclei in human peripheral blood lymphocytes exposed to X-rays and neutrons.
- 2009
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Ingår i: International Journal of Radiation Biology. - 0955-3002 .- 1362-3095. ; , s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: It has been reported that the level of cytogenetic damage in human peripheral blood lymphocytes (PBL) is higher following irradiation at 37 degrees C than at 0-4 degrees C. The mechanisms of this cytogenetic temperature effect are not fully known. The aim of our study was to check whether the effect was related to the indirect or direct action of radiation. Materials and methods: PBL were kept at 37 degrees C and 0 degrees C for 20 min and exposed to 2 Gy of X-rays. In some experiments PBL were isolated and 0.5 M dimethyl sulfoxide (DMSO) was added for 5 min before exposure. PBL were also irradiated at 37 degrees C and 0 degrees C with 1 Gy of 6 MeV neutrons. Micronuclei were scored as the endpoint. Following exposure to X-rays the level of initial DNA damage was also measured by the alkaline and neutral comet assay. Results: The frequency of micronuclei in cells exposed at 37 degrees C to X-rays or neutrons was higher than that after exposure at 0 degrees C. No effect of temperature was seen when PBL were exposed to X-rays in the presence of DMSO. No effect of temperature was observed on the level of DNA damage measured with the alkaline or neutral comet assay. Conclusions: The results of experiments with DMSO indicate that the temperature effect is due to the indirect action of radiation, i.e., via reactive oxygen species. However, this is not supported by the results with neutrons and the comet assay. Possible reasons for the discrepancies are discussed.
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| 3. |
- Hendry, Jolyon H, et al.
(författare)
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Human exposure to high natural background radiation : what can it teach us about radiation risks?
- 2009
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Ingår i: Journal of Radiological Protection. - 0952-4746 .- 1361-6498. ; 29:2A, s. A29-42
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Tidskriftsartikel (refereegranskat)abstract
- Natural radiation is the major source of human exposure to ionising radiation, and its largest contributing component to effective dose arises from inhalation of (222)Rn and its radioactive progeny. However, despite extensive knowledge of radiation risks gained through epidemiologic investigations and mechanistic considerations, the health effects of chronic low-level radiation exposure are still poorly understood. The present paper reviews the possible contribution of studies of populations living in high natural background radiation (HNBR) areas (Guarapari, Brazil; Kerala, India; Ramsar, Iran; Yangjiang, China), including radon-prone areas, to low dose risk estimation. Much of the direct information about risk related to HNBR comes from case-control studies of radon and lung cancer, which provide convincing evidence of an association between long-term protracted radiation exposures in the general population and disease incidence. The success of these studies is mainly due to the careful organ dose reconstruction (with relatively high doses to the lung), and to the fact that large-scale collaborative studies have been conducted to maximise the statistical power and to ensure the systematic collection of information on potential confounding factors. In contrast, studies in other (non-radon) HNBR areas have provided little information, relying mainly on ecological designs and very rough effective dose categorisations. Recent steps taken in China and India to establish cohorts for follow-up and to conduct nested case-control studies may provide useful information about risks in the future, provided that careful organ dose reconstruction is possible and information is collected on potential confounding factors.
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