Solubility assessment of 232Th from various types of soil in Malaysia using USP and DIN In Vitro digestion method

The overall results of the study showed that the concentrations of 232Th radionuclide using DIN digestion method during gastric phase are 0.0015 mg/kg – 0.0554 mg/kg and 0.0015 mg/kg – 0.0139 mg/kg during intestinal phase, respectively. As for USP digestion method during gastric phase are between 0.0877 mg/kg – 0.4964 mg/kg and 0.0207 mg/kg – 0.2291 mg/kg. The results from the measurements in various types of soils indicates some elevation of 232Th concentration in some types of soil compared to UNSCEAR reference values, in which may be a result from the impact of previous mining activity in the surrounding area and considered to be safe. In general, the results of 232Th concentrations from in vitro extraction technique is considered to be safe. By natural processes, thorium ingestion is getting transferred to living beings through different pathways and need to be monitored in order to assess possible hazards. Environmental studies are generally carried out to trace the pathway of radionuclides/radiotoxic elements to reach living organism. Environmental monitoring and meaningful interpretation of data from man-made pollution are more complicated without adequate knowledge about the natural abundance of radioactive elements in the environment.