|U.S. Department of Health and Human Services (DHHS) comments on
Draft ICRP Background Document on
The Optimisation of Radiological Protection
Please send comments and questions to Sam Keith, Department of Health and Human Services, Agency for Toxic Substances and Disease Registry, 1600 Clifton Road, NE, Mail stop F-32, Atlanta, GA 30022, USA, Tel. 770-488-3322, Fax 770-488-4178, e-mail firstname.lastname@example.org.
This background document is useful in appreciating the focus of the ICRP 2005 recommendations.
Medical exposures that carry no benefit to the patient (diagnostic scan for liability purposes) should be considered as being within the scope of this document.
*The draft recommendations state that they exclude medical exposure to patients. However, an additional related category was not addressed. It is recommended that the Commission consider addressing in this document those doses delivered to members of the public from radioactive patients. Such doses may be at the higher end of the exposure curve for public exposure. This is in keeping with the current document’s focus on shifting the public dose curve toward lower doses. The current U.S. dose constraint to this group is 5 mSv per individual exposed by an individual patient. This is 5 times higher than the ICRP proposed public dose constraint, so it is recommended that the Commission address how they see this type dose being optimized. Training in radiation protection matters for nuclear medicine patients, their caregivers, and the general public (since they are surrounded by such mobile sources) appears indicated. Perhaps there should be more info in paragraph (4) where reference is made to addressing medical exposures elsewhere. References might be useful at this point to the medical publications.
This background document on optimization appears to not be consistent with the Draft for Consultation on Assessing Dose of the Representative Individual. The optimization document states that dose constraint must be complemented by the optimization process in order for the public to be considered protected. However, the abstract of the representative individual draft document states that “If the dose constraint for this individual is met, then the Commission’s goal of protecting the public is considered to be achieved,” indicating that optimization is not relevant to the new ICRP focus.
Recommend the Commission include in the document a way to compare radiological and non-radiological cancer risks in the optimization process.
The statement that operators and national authorities have the responsibility for optimization appears to underestimate the potential for useful input by the exposed groups. Recommend this group be integrated as stakeholders in all relevant portions of the text.
The rationale for different protection approaches between the chemical and radiological industries regarding carcinogens should be addressed. For example, the regulation and control of chemical exposures does not appear to address the ALARA concept, despite activities undertaken since the Rio Conference.
The ICRP optimization process as addressed in this document should state that the application of process optimization by line workers, engineers, health physicists, and others without management or regulatory authority is considered to be part of the safety culture.
The document should provide some insight into how optimization can be applied in more globalized situations, e.g., for identical work in different regions resulting in the same level of potential risk, but with divergent stakeholder input. How can input from different regions be integrated into a single solution? The MARSSIM process is an example of an effort toward normalizing D&D efforts.
The initial portion of the document endorses applying optimization to all exposure scenarios, but the examples for the public (Appendix A2) and radon (Appendix A) do not directly integrate optimization.
The use of a writer-editor to make the text read more simply, crisply, and clearly should help the reader understand the document better. This could be quite useful regarding use of new terms where slightly different versions are used in different portions of the text (perhaps indicating different authors). The document also includes some typographical and spelling errors. The need for this review is consistent with the Commission’s position toward simplicity and clarity.
Exposures should be both justified and optimized. Since the text only addresses optimization, recommend adding text in appropriate sections that directs the reader to current ICRP thinking on justification. In section 2.2, the document does address optimization regarding the new wave of interventional (i.e., digital) radiography where increased dose can provide equally good or better images where the improvement may not justify the increased dose.
*Adding a glossary would help both the reader and the authors assure consistency of use. As an example, it would be useful to know the difference between the terms “involved parties” (para 45), “stakeholder” (para 46), and “relevant parties” (para 47).
Pg 8 para 1. In the first sentence, recommend adding the responsibilities of the exposed groups.
Pg 15 para 22. Editorially change “As it is” to “As there is.”
Pg 15 para 23. The text states that dose limits are used only in planned situations, however, they are also used in unplanned exposures. The 5 mSv/a public dose limit is such an example. The definitions of dose constraint and dose limit should be clarified.
Pg15 para 24. ICRP may want to consider addressing operations involving radiation that may not require permitting, e.g., some uses of x-rays and radioactive material preparation using particle accelerators that a state or nation has not developed regulations to control. In sentence 2, after “Such facilities” recommend adding “typically” in order to cover these radiological activities.
Pg 16, Figure 1, Controllable Existing Situations graph. The graphs in this figure are confusing and needs additional text to explain their meaning. In controlled existing situations, the existing exposure will be lower than the constraint if the system is effective. If the dose exceeds the constraint, there is an obvious need to reduce the dose, so the recommended change is to draw the constraint at a level above the existing exposure, and then show further reduction through optimization.
*Pg 18. It is not clear why the transfer of exposure is necessarily bad. Increasing worker training, using fewer workers with more individual exposure could be a prudent use of optimization, or a first step in the optimization effort. Then the goal would be to continue optimizing in an attempt to achieve lower individual dose.
Pg 19, representative attributes list. Ritualistic self and group exposure scenarios can represent significant exposure and should be added to the document. Under characteristics of exposure add median since its value can drive the optimization process in a somewhat different direction than the mean where only a few individuals are highly exposed. Considering both can result in identifying more relevant dose reduction strategies.
-Under characteristics of exposure, consider adding supplemental exposures (e.g. medical) as regards the overall exposure of the individual. Multiple self referral for medical tests involving radiation exposure could cause determiniatic effects, and one would want to consider this when assessing the effects of other sources of radiation
-Under social considerations and values, add to the last entry “and those giving the exposure.”
-Under environmental considerations, add an entry reading “exposures of other potential carcinogens”
-Under technical and economic considerations, add “risks introduced by implementing options” since one would not want an actions that reduces dose to add a higher level risk.
Pg 20 para 34. The paragraph gives 7 characteristics of the optimization process, but it does not capture all the ideas presented through paragraph 47. Those subsequent paragraphs would benefit from rearrangement to follow the structure and tone of paragraph 34, and then writing one paragraph per characteristic.
Pg 20 para 34. Recommend changing “concerned organizations” to “relevant parties” as addressed in paragraph 47.
*Pg 21 para 38. The paragraph addresses “judging that no further dose reduction is reasonable.” However, paragraph 36 states that the process is iterative and always questions whether enough has been done. The 1st indicates that there can be a finality while the latter indicates this can never occur. Recommend adding text on how to work effectively with both in reaching decisions.
Pg 23 para 45. Recommend that all relevant information be provided to and by (rather than just to) the involved parties. This 2-way, open process should also encourage all the involved parties to share their unique knowledge and goals for the optimization process. As currently written, it might appear that “involved parties” are only members of the public and not workers, managers, and regulators. All these groups should be included under than umbrella.
*Pg 23 para 46. The paragraph should be reworded to make clear that "any level of exposure can involve a risk" is, at present, an assumption for very low doses rather than the fact that seems to be implied. The paragraph could emphasize that we currently assume that very small levels of exposure have very small risks and that optimization is aimed at making sure that the doses are as small as reasonably achievable, acknowledging the uncertainties associated with the risks of very small doses.
Pg 24 para 50. Recommend adding that stakeholders can have an organizational interest in the outcome. This adds coverage to organizations with agendas whose representatives can rotate. This can apply to the management, operator, regulator, or other stakeholder whose expression of the organization’s interests may vary based on their personal interest, adding a degree of uncertainty to the input as time passes. Recognizing that this uncertainty can exist and incorporating it openly into the discussions and procedures developed can help the interested parties work through digressions in a positive manner.
Pg 24 para 51 (plus parts of paragraphs 48 and 50). Should an exposed but nonvocal part of society also be considered to be a stakeholder? This document may want to include them in the definition of stakeholder, and provide opportunities to entice them to become participants so that their input can enhance the process while reflecting a broad and balanced cross-sections of the exposed population.
*Pg 24 para 55. Based on paragraph 57, the bold heading could be rewritten as “Temporary end point of the optimization process” to indicate that the end reached in one clean-up effort may be expected to be reviewed in the future and the process reengaged as prevailing circumstances (para 55) change over time.
Pg 25 para 56. To the end, add “unless the optimization process identifies a goal that is below the exclusion levels.”
Pg 25 para 58. The 2nd sentence should be revised or deleted since a dose is not a tool. Also the text does not make it clear how a residual dose is likely to be important for the workers or population other than for satisfying their protection goals.
Pg 25 para 59. This paragraph is unclear. The concept of “existing situation” needing adjustment to a “normal situation” introduces new terms that are not defined and a concept that is not described. Recommend it either be clarified or deleted.
Pg 26 para 62. In sentence 1. editorially hold the very together and move “only” to after “estimated.” In sentence 2, since modeled doses are estimates, revise to read, “average individual doses can be modeled to provide estimates used to define subgroups of exposure to a given source.” In sentence 3, add direction from the source travel routes, and home and work locations. In the last paragraph, there is an apparent assumption that exposure ends, but this is not in consonance with the previous section that assumes that exposure continues at an acceptable level following cleanup.
Pg 27 para 69. Recommend deleting “as well as the inherent uncertainties attached to the dose assessment.” Although it is true that collective dose hides uncertainties, this is also the case with individual dose assessment. Uncertainties are an inherent part of each dose assessment, whether collective or individual. The text implies that individual dose assessments do not suffer from this, and this implication should be clarified to help the reader understand this.
Pg 28 para 70. In the last sentence, after “collective dose” recommend adding “and its uncertainty.” It is useful to point out that the new collective dose effort in this document refers to a range of dose possibilities.
Pg 29 para 73½. Recommend changing “all sources” to “all regulated sources” since the system of radiological protection is not applied to unregulated sources of exposure (e.g., storage of potassium compounds in chemistry labs or grocery stores, or road workers adding gravel or asphalt to roads, all of which can represent exposure sources).
Pg 30 para 76. To the end, recommend adding “and among the exposed populations of workers and the public.” If these groups practice safety of a regular basis, they may be more likely to be a positive influence on the optimization process.
Pg 36 para 2.1, 2nd para. Since the previous paragraph addressed the nuclear fuel cycle, the identification of only refueling in the paragraph is too limited. As such, the text could be revised to include the other activities associated with the nuclear fuel cycle.
Pg 38 para 2.2. On line 4, editorially remove “the” in two places.
Pg 38 para 2.4. This section should address a need to provide guidance on building materials, since brick, asphalt, stone, and concrete can increase workplace exposure over wood, while gases emitted from treated wood may also be toxic. It appears that the Commission should address a comparison of radiological and non-radiological cancer risks in the optimization process.
Pg 39, 1st para. Recommend changing “numbers of workers” to “percentages of workers” to accurately reflect Figure 4.
Pg 39, 2nd para. Since this paragraph provides specific percentage values, the relavant reference should be included. A statement should be included to state that exposure from some natural sources was excluded (e.g., exposure from brick, stone, asphalt paving, etc.).
Pg 39 and 40, Relative Weighting, 1st para.
-Recommend removing sentence 3. Optimized protection solutions are not aimed at lowering both the number of people and their mean dose in the whole dose range over time. Doing so is the result of shifting radiological and non-radiological work which reduced the number of workers.
*-Consideration should be given to either removing Figure 4 and its related text or enhancing the text with sufficient information that validates the interpretation regarding the impact of optimization of the shifting of the curve from 1996 to 2000. This is because there are other plausible explanations other than optimization exist that could fully explain the shape change (e.g., aging of the work force that removes the most highly qualified and senior workers doing the highest dose jobs and are replaced by a larger number of younger workers, or specific global jobs such as RV head replacement that can skew the curve over a small number of years). The values being presented as % of workers rather than number work workers also makes interpretation difficult. Two graphs showing % of workers and # of workers are needed to help understand what is being presented (similar to including both mean and median as addressed elsewhere).
-The graph reflects a reduction only for the highest dose group and not for the “upper part of the dose distribution.” If error bars were included, perhaps the only significance would be for the 5-10 and >20 groups. The increase in 1998 for the 5-10 group is worth discussing. The drop for >20 should be addressed in terms of any shift in the distribution (i.e., was it the result of giving many more low dose workers a little more exposure). One could interpret the 1998 reduction for the >20 group as having been offset by the large increase for that year in the 5-10 group. Then the drop in 2000 for the >20 group could be explained by the increases in the 1st 3 and the 6th groups. Perhaps there is a shift in dose distribution, but some additional information should be presented in order for the reader to clearly appreciate the relevance of the figure to optimization and other competing events.
-It should be addressed that new work efforts (e.g., reactor vessel head replacement as a result of boron corrosion) may need to result in increasing doses across the board for some period, with optimization aimed at minimizing the increase in doses received. Continuously reducing the dose with time without properly addressing changing needs in the future would seem to be contrary to the goal of supporting justified uses of radiation and the optimization process.
Pg 40, Relative Weighting, para 2. In line 2, editorially change “built” to “build.”
Pg 41 para 4. Editorially revise the formatting and unclear text. Note that the absence of a safety culture is some industries may be consistent with other industries (chemical protection) and activities (controlling vehicle speed on roadways). Recommend addressing a desire to infuse the safety culture concept into all industrial and public regulation.
Pg 41, section 4, last para. Change the 1st line to read, “operating management should” since this is a guidance and not a regulatory document.
Pg 41 section 5. Change “balance radiological impacts “ to “balance radiological and non-radiological cancer impacts” since the goal is overall protection.
Pg 43, section 1, para 1. It is unclear what is being distinguished in sentence 1. What is meant by “exposures caused by … exposure situations”? It the intent is to address natural sources, then say so for clarity.
*Pg 43, section 1, para 2. The quote from ICRP Publication 60 is inaccurate where “almost all public exposure” in concerned relative to this background document, since it addresses exposure from natural sources. NCRP documents indicate that almost all public exposure taken in total cannot be controlled by optimization. This includes cosmic radiation, terrestrial radiation (from construction material), internal radiation (from K-40), and outdoor radon are virtually uncontrollable. Recommend stating the extent to which the text in ICRP Publication 60 does and does not apply to this background document. Also map a path forward realizing and embracing this concept.
Pg 44, section 2, para 2. Is reference xx yet to be developed?
Pg 44, section 2, para 5. “Series of documents”
*Pg 45, section 2, para 1. The text states that “the source for which protection is being optimized is clearly and unambiguously identified” regarding hospital exposure. However, radioactive patients are allowed to deliver 5 mSv to a member of the public. This dose overshadows all dose reduction efforts addressed in this document under the optimization process. Shouldn’t this source be goal #1 for optimized reduction? The dose constraint of 1 mSv/a is 20%, 10%, 5%, or even lower depending on the number of patients to which an individual is exposed in a year. Perhaps optimization does not have the potential for the full reduction to the constraint dose unless regulations are changed.
Pg 45, section 2, Selection, para 3. Recommend adding radioactive patients to the list of situations presented. Recommend addressing how to constrain dose to any individual from a radioactive patient.
Pg 47, Relative weight, para 2.
-Should the correct reference be to Figure 4 (probably not) or to Figure 7.
-The paragraph addresses decision-making for a few generations (which would be perhaps 100 years based on assuming 3 generations at 30 yr/generation). However, Figure 7 has its 1st drop at 1000 years (30 generations). This indicates that the drop to 0.1 would occur at 100 instead of 1000 years, with the same rational that assurance drops after a few generations.
Pg 48, section 5. This conclusion paragraph appears to weaken the justification for including stakeholders in the optimization process by not addressing this group.
Pg 50, section 1, para 2. The reference “EPA FL” is not in the reference list for this annex. Also delete “but” from “well known but.”
*Pg 50-51, section 2. Optimization should be, but is not, fully addressed in this section. Recommend the text be consistent and address how to press radon doses lower through optimization. Since this represents the largest natural source of exposure, it should probably deserve the best effort in developing a section for its optimization.
Pg 51, section 3, para 2. In addition to identifying radon-prone areas, identify buildings containing materials that are prone to emitting radon, such as homes with granite countertops, stacked stone accents, or firebricks.
Pg 51, section 3, Step (a), para 3. The selection of workplaces should include floors below grade (workspaces below the ground floor) and floors completely surrounded with concrete (e.g., pay booth in a parking lot).
Pg 52, section 3, Step (b). Recommend that it be stated that “closed conditions” designed to maximize the radon concentration during the measurement period may not provide realistic conditions as inputs for the optimization process. It can be noted that U.S. EPA radon measurement guidance recommends using closed house conditions that can maximize the radon concentration beyond normal exposure scenarios.
Pg 52, Step 3c. Recommend giving the rationale for differences in protective actions for children and the elderly in terms of sensitivity, exposure duration, etc. With more individuals living past 100 years, the relevance of this difference is not necessarily obvious.
Pg 52, Step 3c, para 3. It is not considered true that radon is not controllable by direct actions on the source. Granite countertops, interior stone work, and brick siding are all removable, but at a cost. One could look at removing stone work in judiciary buildings and fireplaces in homes, or increasing ventilation in energy-efficient structures.
Pg 52, step 3, para 3. Recommend removing “almost.” It is virtually impossible to reduce radon concentrations to zero.