Occupational Intakes of Radionuclides Part 1 - ICRP

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DRAFT REPORT FOR CONSULTATION
PREFACE
The system of protection recommended by the International Commission on
Radiological Protection is the basis for standards and working practices throughout
the world (ICRP, 1991, 2007; IAEA 1996a). Fundamental to the application of ICRP
recommendations are the protection quantities defined by ICRP, equivalent dose and
effective dose. While the definition of these quantities remains unchanged in the most
recent recommendations (ICRP, 2007), there have been important changes that affect
the values calculated per unit radiation exposure. Committee 2 of ICRP is responsible
for the provision of these reference dose coefficients for the assessment of internal
and external radiation exposure, calculated using reference biokinetic and dosimetric
models, and reference data for workers and members of the public. Following from
the 2007 Recommendations, Committee 2 and its Task Groups are engaged in a
substantial programme of work to provide new dose coefficients for various
circumstances of radiation exposure.
The 2007 Recommendations (Publication 103, ICRP, 2007) introduced changes to the
radiation weighting factors used in the calculation of equivalent dose to organs and
tissues and also changes to the tissue weighting factors used in the calculation of
effective dose. In addition, an important development was the adoption of reference
anatomical computational phantoms (that is, models of the human body based on
medical imaging data), in place of the composite mathematical models that have been
used for all previous calculations of organ doses. This process has commenced with
the adoption of reference male and female adult models (ICRP, 2009) and will be
continued with the adoption of paediatric phantoms. Publication 103 also clarified the
need for separate calculation of equivalent dose to males and females and sexaveraging
in the calculation of effective dose (ICRP, 2007). In the revision of dose
coefficients, the opportunity has also been taken to improve calculations by updating
radionuclide decay data (ICRP, 2008) and implementing more sophisticated
treatments of radiation transport (ICRP, 2010) using the ICRP reference anatomical
phantoms of the human body (ICRP, 2009). These improvements impact on dose
calculations for external exposures as well as for internal emitters.
This report is the first in a series of documents replacing the Publication 30 series
(ICRP, 1979, 1980, 1981, 1988b) and Publication 68 (ICRP, 1994b) to provide
revised dose coefficients for occupational intakes of radionuclides (OIR) by inhalation
and ingestion. The revised dose coefficients have been calculated using the
Publication 100 (ICRP, 2006) Human Alimentary Tract Model (HATM) and a
revision of the Publication 66 (ICRP, 1994a) Human Respiratory Tract Model
(HRTM) which takes account of more recent data. In addition, information has been
provided on absorption to blood following inhalation and ingestion of different
chemical forms of elements and their radioisotopes, in those cases for which it is
judged that the data are sufficient to make specific recommendations. Revisions have
been made to many models for the systemic biokinetics of radionuclides absorbed to
blood, making them more physiologically realistic representations of uptake and
retention in organs and tissues and of excretion.
The reports in this series provide data for the interpretation of bioassay measurements
as well as giving dose coefficients, replacing Publications 54 and 78 (ICRP, 1988a,
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