books.google.fr - Naturally occurring radionuclides are found throughout the earth's crust, and they form part of the natural background of radiation to which all humans are exposed. Many human activities-such as mining and milling of ores, extraction of petroleum products, use of groundwater for domestic purposes, and...https://books.google.fr/books/about/Evaluation_of_Guidelines_for_Exposures_t.html?hl=fr&id=8uhuAgAAQBAJ&utm_source=gb-gplus-shareEvaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials