Siberian Biophysics conducted a pilot study of biological effect of low doses of gamma radiation. The results of the study submitted to the Journal of Environmental Radioactivity.
The authors of the study tried to identify the characteristics of exposure to low doses of gamma radiation on living beings and to understand the difference between the effects of gamma radiation on living organisms from alpha and beta radiation. As a test of the body they used luminous bacteria Photobacterium phosphoreum, which are extremely convenient object for the analysis of all aspects of radiation exposure. A source of gamma radiation was “hot particles” containing cesium-137 found in the sediments of the Yenisei river near the village of Atamanovo in Krasnoyarsk region. To conduct the research, luminous bacteria were placed in the experimental capsule where they have experienced exposure to radiation of different power and duration at three temperatures (+5°C +10°C +20°C).
Differences in biological effects of different radiation types (alpha, beta and gamma) are related to the nature of these radiations. So, alpha and beta radiation – a stream of charged particles (respectively of the nuclei of helium atoms and electrons) that are actively ionize the environment. Gamma radiation is a electromagnetic radiation of high energy and low ionizing ability. These differences have impact on the biological effects not only in high-dose, but low doses effects. Low doses effects at present, are the least studied and therefore most interesting to scientists.
As a result of experiments and comparisons with the findings of previous studies in this field, scientists have come to several significant conclusions.
First, if the effect of low alpha – and beta-radiation on living organisms can be described by the hormesis model (according to which the radiation can have not only negative but also positive impact), for low-intensity gamma radiation under similar conditions found only an overwhelming influence, which is described by a linear dependence in the coordinates of the dose-effect.
Thirdly, the impact of the luminous bacteria low doses of gamma radiation at temperatures of +5°C and +10°C, scientists have not registered any vast radiation effect in the course of the experiment (up to 175 hours). Under similar influence of gamma radiation at the temperature of +20°C, the researchers observed a suppression of the natural luminescence of the marine bacteria, therefore, these organisms were exposed to the toxic effects. Scientists explain this by the fact that at higher temperatures accelerates the metabolic processes, and bacteria become more sensitive to radiation.
And, fourth, if the risk of radiation exposure is often associated with changes at the genetic level, at low doses of gamma radiation, scientists have found changes in the genes responsible for vital functions of bacteria.
According to one of the authors of the publication, Professor of the Siberian Federal University and the academic Institute of Biophysics SB RAS Hopes Kudrjashovoj, the results of this study are of both fundamental and practical importance: “the results Obtained help to understand the nature of biological effects of low-intensity radiation at the cellular level. Cells of luminous bacteria are an extremely convenient object for such studies. The applied aspect of the work associated with the use of luminous bacteria for determination (monitoring) toxicity of the environment. It is known that these bacteria for nearly fifty years is very widely used for monitoring the toxicity of environmental chemical contamination. Our research shows the prospect of using these bacteria to determine (monitoring) toxicity of the radioactive pollution”.