Soil Radioactivity Levels and Ionizing Radiation Hazard Occurrence in the Crati Basin, Calabria (Southern Italy)

The natural materials, as rocks, soil, vegetation and groundwater, contain radioisotopes which are subjected to the process of the radioactive decay that creates terrestrial radiation. It consists of Ionizing Radiation (IR) or Non-Ionizing Radiation (NIR). NIR is a form of radiation with less energy than ionizing radiation. The process does not involve the removal of electrons from atoms or molecules of materials. Conversely, IR is released when atoms and molecules lose electrons, affecting air, water and living tissue. IR can move invisible and access to human tissues altering the cells of human body and causing hazards such as skin or tissue damage. This study aims to assess the natural radioactivity levels in soil samples from the Crati basin, the largest basin in the Calabria region (southern Italy) and to calculate ionizing radiation hazard occurrence which can cause cell damages in the local inhabitants. The study area is lithologically formed by plutonic and metamorphic crystalline rocks of the Sila Massif, by crystalline and sedimentary rocks of the Coastal Chain and by carbonate and siliciclastic sedimentary rocks of the Pollino Massif. The climate of the area is largely influenced by its geography and its location in the middle of the Mediterranean region. A sensitive detector, including a Geiger–Muller tube with an external NaI (Tl) probe, was used for the survey. Results evidenced that the mean equivalent dose rate for natural sources of radiation in sampled soils is 90.38 μSv/h, with a maximum value of 195 μSv/h and a minimum of 55 μSv/h. The average radiation levels in the soil samples were higher than the global average dose rate values reported by UNSCEAR. However, the difference was not statistically significant enough to pose a fatal cancer risk to the population in the study area. The soil radioactivity levels in the Crati basin can be referred to the lithological types occurring in the area, which contain primary minerals responsible of the radionuclide’s activity.