The metabolism of 3H compounds and limits for intakes by workers

A wide variety of 3H compounds with different physico-chemical and radiotoxic properties are produced and used throughout the world. For the purpose of worker radiation safety, 3H compounds have been divided into five classes: oxide, gaseous, insoluble, soluble organic substances and precursors of nucleic acids. Based on recent radiobiological and dosimetric data the quality factor for 3H has been suggested (QF = 2). Standards for oxide and gaseous 3H, reduced by a factor of 3-10, as compared with International Commission on Radiological Protection (ICRP) recommendations, have been suggested. New standards, 2-30 times lower than those for 3H oxide, have been worked out for the other three classes of 3H compounds. A limit for removable surface contamination from nonvolatile forms of 3H has been proposed (LSC = 1 kBq cm-2).