Exploration of biological phenomena of below-background natural radiation

Worldwide, humans are exposed to a mean background radiation dose of about 2.4 mSv per year. Natural background radiation is a constant and ubiquitous environmental factor affecting all living things on this planet, and organisms have evolved in the presence of the natural radiation since the first forms of life appeared on Earth. However, its role in biology is still not completely understood. Here, we summarize the interesting biological responses in organism at below-background radiation and highlight recent development of the studies with molecular based analyses. To date, deprivation of natural background radiation has been carried out with shielding chambers or by conducting experiments in underground laboratories. In recent decades some research groups have reported changes to growth-related biological endpoints in microorganisms and mammalian cells under low-background radiation conditions. Moreover, new technologies, such as DNA microarray and next-generation sequencing, have begun to shed fresh light on the molecular mechanisms of these biological phenomena. Although there is no consistent explanation for the mechanisms so far, such studies might provide clues toward an understanding of the biological responses to natural background radiation.