Rio Tinto is a large multinational mining and processing company producing a range of resources throughout the globe. Rio Tinto, as part of its portfolio, is a major shareholder and operates two uranium mines (Rossing in Namibia and Ranger in Australia) and also has a range uranium exploration activities. Rio Tinto welcomes the opportunity to comment on the ICRP Draft Report on Radiological Protection against Radon Exposure.
As stated in the document the most significant risk for lung cancer is smoking and the smoking risk also dominates the radon related risks. This needs to be clearly articulated throughout the document. Specifically Rio Tinto supports the comments made by Doug Chambers of SENES.
The following are specific comments about other aspects of the draft report:
Paragraph (30) Lines (797-799); paragraph (33) Lines (861-867) and elsewhere in report: The use of SI units is (ie, ”J”, “Jm-3”) should be the preferred mechanism for report by the ICRP rather than historical units like “WL” and “WLM”. As such the primary text should be SI units and parenthesis used for historical units. Also the units of” J h m-3” is not a “real” SI unit because it inherently incorporates a breathing factor to allow direct comparison with the historic units. This does cause problems where different breathing rates are used (such as risk for public vs occupational). A more correct use of SI units would be to express the risk as a factor of “J” which removes the need for the breathing factor. This also leads to future documents where dose conversion factors can be true SI units (ie “mSv/J” or “mSvJ-1”). It also would be far more consistent with other ICRP dose conversion factors (ie “mSv/Bq”).
Paragraph (63) Line (1158): Would recommend the inclusion of “further” between “of the” and “application” as the use of dose constraints and reference levels is already part of the optimisation process.
Paragraph (68) Lines (1184-1190): This paragraph seems to imply that if a occupationally exposed individual is exposed to workplace related radon, but the radon is not a component of the operational practice, than this exposure can be ignored. This may lead to cases where the dominant area of radiation exposure is not considered and will potentially lead to confusion and concerns. It also appears to be in direct disagreement with the statements in Paragraph (112) Lines (1561-1567) which states that for in workplaces where the workers are occupationally exposed than the radon component be included in the assessment against the occupational limit. It is recommended that if a worker is already subject to occupational exposure monitoring, assessment and control than all components need to be assessed including radon.
Paragraph (100) Lines (1478-1479): Given the dominance of smoking to the radon risk should there also be mention of high smoking prevalence areas.
Figure 7 Line (1588): In line with the comments on Paragraph (63) the line on the extreme right should be modified from “A few cases (mines, spas....)” to “Occupational exposed individuals/A few cases (mines. Spas...)
Figure 7 Line (1588) and elsewhere in the document: The rationale 300Bq/m3 for workplaces seems to be flawed. If 300Bq/m3 has been chosen for homes based on a potential dose ~10mSv/y than the same level of radon would give a far lower dose from the occupational standpoint given the far lower occupational factor (ie a dose closer to 3mSv/y). If the use of a comparable radon concentration is the recommendation of the ICRP( which may not be justified based on this discrepancy) than it should be justified using a different approach to house hold exposure.
Paragraph (171) Lines (2022-2027): For future documents providing Dose Conversion Factors it is recommended that the preferential units are true SI (ie mSv/J) and hence directly compatible with existing ICRP approaches (ie mSv/Bq) (see comments on Paragraph (30)).