Abstract- This report is the first in a series of documents replacing the Publication 30 36 series and Publication 68 to provide revised dose coefficients for occupational intakes of 37 radionuclides (OIR) by inhalation and ingestion. The revised dose coefficients have been 38 calculated using the Publication 100 Human Alimentary Tract Model (HATM) and a 39 revision of the Publication 66 Human Respiratory Tract Model (HRTM) which takes 40 account of more recent data. In addition, information has been provided on absorption to 41 blood following inhalation and ingestion of different chemical forms of elements and 42 their radioisotopes, in those cases for which it is judged that the data are sufficient to 43 make specific recommendations. Revisions have been made to many models for the 44 systemic biokinetics of radionuclides absorbed to blood, making them more 45 physiologically realistic representations of uptake and retention in organs and tissues and 46 of excretion. 47 The reports in this series provide data for the interpretation of bioassay measurements as 48 well as giving dose coefficients, replacing Publications 54 and 78. In assessing bioassay 49 data such as measurements of whole-body or organ content or urinary excretion, 50 assumptions have to be made about the exposure scenario, including the pattern and 51 mode of radionuclide intake, physical and chemical characteristics of the material 52 involved and the elapsed time between the exposure(s) and measurement. This report 53 provides some guidance on monitoring programmes and data interpretation