GATE MARIM DB, a Monte Carlo database for dose assessment of microorganisms exposed to natural α-radioactivity

The International Commission on Radiological Protection (ICRP) recommended in 2007 a systematic approach to assess the radiological effects on non-human species. This method transforms radiation exposure into dose rates for living matter, using Dose Conversion Coefficients (DCCs) specific to radionuclides and organisms. Among the long-lived radionuclides, those of the ²³⁸U and ²³²Th decay chains dominate in terms of contributing to natural radiation exposure of non-human species, with significant dose contribution due to their alpha emissions. The ERICA tool was designed to assess dose rates for living organisms weighing from 10^-6 kg to 10³ kg. This study extends ERICA’s applicability by using the open-source GATE Monte Carlo platform to compute DCCs for smaller microorganisms exposed to alpha particles (internal or external exposures). This research compares GATE’s results to ERICA’s near its validity limits and explores how DCCs evolve with environmental composition and microorganism size. The open-source GATE MARIM database, including DCC values for 15 alpha-emitting isotopes from the ²³⁸U and ²³²Th decay chains, is now available with a Python Jupyter notebook interface enabling the calculation of dose rates for microorganisms exposed to natural radioactivity.