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ICRP: Free the Annals!

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Submitted by Dr H H Landfermann on behalf of BfS, BfS - Federal Office for Radiation Protection of Germany
   Commenting on behalf of the organisation
Document Recommendations
 
General Comments

In general the document is in good shape, but in parts of the document, e.g. chapter 3, a very complex language is used. These parts make it difficult to deal with the subject. There are still many redundancies in the text describing characteristics of the three types of situations and three categories of exposures (see also specific comments below). This makes some parts of the text difficult to read and might be a source of confusion and misinterpretation. The text should be consolidated accordingly.

Specific Comments

1. Introduction

Paragraph (17): The statement that “nominal risk coefficients do not apply to specific individuals” is very fundamental. Therefore, it should be considered to mark important statements of the commission by bold types calling the reader´s attention to those points.

Paragraph (22): “.. not recommended gender-specific data for the purposes of radiological protection..” and “..effective dose is intended for use as a protection quantity on the basis of reference values and therefore should not be used for epidemiological evaluation, nor should it be used for any specific investigation of human exposure” see Paragraph (17).

2. The Aims and Scope of the Recommendations

Paragraph (26): It should be emphasised that the recommendations are based on scientific knowledge, but also on expert judgement.

Paragraph (29): The introduction of the term “tissue reactions” replacing “deterministic effects” is not convincing. The term might not be totally correct for all situations, however “deterministic effect” became a kind of a trade mark and would maintain continuity in the recommendations.
“Stochastic effects” should also be printed in italics.

3. Biological Aspects of Radiological Protection

Paragraph (54): The second last sentence is difficult to understand, better would be: “Of particular importance are the advances in understanding effects on DNA by radiation like the induction of complex forms of DNA double strand breaks, the problems experienced by cells in correctly repairing these complex forms of DNA damage and the consequent appearance of gene/chromosomal mutations.”

Paragraph (55): For an easier understanding the following rephrasing of the paragraph is suggested: “Although there are recognised exceptions, for the purposes of radiological protection the Commission judges that the increase in the incidence of cancer or hereditary effects will rise in direct proportion to an increase in absorbed dose in the relevant organs and tissues. This view is scientifically reasonable to assume in the low dose range below 100 mSv and is supported by the weight of evidence on fundamental cellular processes coupled with dose-response data.”

Paragraph (56): For a better understanding the following rephrasing of the first sentence is suggested: “Therefore, the practical system of radiological protection recommended by the Commission will continue to be based upon an hypothesis generally known as ‘linear non-threshold’ or LNT. The assumption is that at doses below around 100 mSv a given increment in dose will produce a directly proportionate increment in the probability of incurring cancer or hereditary effects attributable to radiation.

The scientific basis in favour of a DDREF = 2 is weak. In comparison to the uncertainties of the cancer risk coefficients the introduction of a factor 2 is unjustified and an unnecessary complication in the system of adjusting and weighting for different radiation situations. The dose-dose rate-effectivity factor is only used for doses below 200 mGy and/or dose rates below 0.1 mGy/min. The biological data base in this low dose range is variable. Dose effect relations fit to different models including linear and linear-quadratic curves. Radiobiological experiments about bystander effect, genomic instability, inverse dose rate effect for mutation induction etc. even indicate a hypersensitivity at the low dose range. Calculations of a DDREF vary between 1 to 3 or more. Also, the epidemiological data show no scientifically convincing evidence for a DDREF. These data strongly depend on the dose range looked at. Recent epidemiological studies about radiation workers after low dose rate exposures almost agree with cancer risk estimations of the atomic bomb survivors after acute radiation exposure. Therefore, a DDREF even lower as two is hard to defend. To avoid an underestimation of risk in the low dose range and during chronic exposition it is recommended to abandon a DDREF of 2 and to use instead a DDFEF of 1.

Considering the uncertainties in risk estimations, the DDREF under two as proposed by BEIR VII does not make sense.
The reference of the report of the French Academies is missing.

Paragraph (57) “… it is not appropriate, for the formal purposes of public health, to calculate the hypothetical number of cases of cancer or heritable disease that might be associated with very small radiation doses received by large numbers of people over very long periods of time” see Paragraph (17). An indication about the “cutting points” for small radiation doses, population size, and considered time periods would be helpful.

Paragraph (61) to (64): A DDREF should not be retained and is considered as a unnecessary complication (see paragraph 56).

Paragraph (67), (68) and (72):
In the past hereditary radiation effects were believed to be important in respect to the health of a national population. Although there have been some changes in the modelling in the genetic risk, the risk coefficient for the first two generations stays almost the same as compared to ICRP 60. The most important change is that the risk estimates only for the first two generations should be taken. Therefore, the genetic effects were not estimated for a population in equilibrium, but only for two generations.
In Annex A, the authors argue that the risk estimates for the population at equilibrium should not be taken because estimation for mutation components and selection coefficients to hundreds of generation are unsure and that people are generally interested in the well being of their children and grandchildren. In addition, because of reduction of reproductive fitness of the affected progeny, many radiation induced mutations are strongly selected against. BfS thinks, that it is a step backwards – compared to ICRP 60 –, to take only the first two generations into consideration, because:
• first recessive mutations will show up in later generations and represent therefore a severe risk, also mutations that will induce multifactorial diseases due to epistasis;
• second our interest in the human race should go further on then just to our grandchildren;
• third due to medical improvement also mutations that would never have been manifested in a population will not be selected against.

Therefore, a reduction in the genetic risk coefficient from 1.3 (ICRP 60) to 0.2 (new recommendation) is not justified.
Also considering a possible radiation induced genomic instability, the proposed reduction of the genetic risk is difficult to defend.
The joining of cancer risk coefficients with coefficients for hereditary effects which are not restricted to cancer but refer also to some forms of anomalies in future generations is like comparing apples and oranges. The effective dose might be considered only as somatic effective dose and hereditary effects should be treated separately, similar to the teratogenic radiation effects which are not included in the effective dose weighting process.

Paragraph (69), (70): Especially the nominal risk coefficients have changed and are now based on incidence data, gender and age averaged. By this, the radiation sensitivity of the woman is not taken into account. Tissue weighting factors have changed especially for breast and gonads. Gender specific differences have not been recognized. Especially for the breast this should be changed, but also for other tissues. As a minimum, the rationale for not considering gender specific differences for radiation protection purposes. An important issue would be to state that this is not leading to any underprotection of parts of the population.

Paragraph (73): The detriment-adjusted nominal risk coefficient for cancer is based upon estimates of lethality/life impairment weighted data on cancer incidence. The factors used for the weighting of data e.g. quality of life seem to be based on subjective judgement, not exactly defined and dependent on the medical state of the population averaging over all populations; this is an issue which need more explanation. Further, it is recommended to harmonize the risk calculation with the one used by WHO for their calculations of global burden of disease.

4. Dosimetric Quantities

It is appreciated that
• “equivalent dose” and “effective dose” will be the main dosimetric quantities furthermore even they cannot be used directly as quantities in radiation monitoring;
• the effective dose is really additive now;
• operational quantities are not changed, this is a practice-related advantage, there is a strong demand of the radiation protection professionals for continuity;
• the new evaluation of the collective dose quantities is clearly defined: to optimize and reduce the radiation exposure of groups of occupationally exposed persons or of the public; it is really seen as an instrument for optimization, for comparing radiological technologies and protection procedures and it is not intended for use in epidemiological risk assessment.

At present the internal dosimetry terminology used in occupational and public exposure by ICRP is quite different to that used in nuclear medicine by MIRD. Therefore within the DOCAL Task Group of ICRP a new formalism has been developed which is more rigorous than the present one, which is more related to the ICRU quantities and which is intended to be used in all fields of internal dosimetry. It is planned that this new terminology will be used in the revision of ICRP Publications 30/54/68/78 and that it will also be used by MIRD in the future. It is regretted very much that this terminology is not used in this document which is intended to be the ICRP basis for the next decade(s).

The definition of the absorbed dose by using the mean energy imparted by ionising radiation in a volume element partly leads to the misinterpretation that not the total energy imparted in the volume element would be considered.

In this document generally the term "conversion coefficient" is used instead of the former term "conversion factor". However, in external dosimetry there are some conversion coefficients/factors which relate for example organ doses to kerma. In such situations these values should be called conversion factors because they are dimensionless.

In general in this document doses to workers and members of the public seem to be considered while the medical aspects (doses to patients) are neglected.

It might be confusing in the future that when reading about the effective dose E it will not always be clear which concept and which weighting factors have been used for its derivation – ICRP Publication 60, the present (draft) recommendations or perhaps any future recommendation.

Paragraph (88): In section 3 “Biological Aspects of Radiological Protection” “tissue reaction” (if used at all, better to use the “old” expression “deterministic effects”) is defined, therefore is it unnecessary to have the brackets after the term. with additional explanations (“sometimes also, but less precisely, termed deterministic effects”), see also paragraph (93). The specific term “detriment”, e. g. having no expression in German, might be explained in detail. The last sentence should read: "The underlying principle adopted by ICRP has been to use absorbed dose as the fundamental physical quantity of energy deposition per unit mass, …".

Paragraph (94): The last sentence should read: "… which is a quantity used for the internal and external exposure to radiation fields and based on the primary physical interactions in human tissues ...".

Paragraph (96): The last but one sentence should read: "… the summing of weighted mean doses in different organs and tissues of the human body…." because otherwise the summation of organ and tissue doses makes no sense.

Paragraph (98): The last sentence should read: "Radionuclides may be distributed homogeneously throughout body tissues (e.g. tritiated water, 40K) …".

Paragraph (113), line 13: misprint the wT .

Paragraph (114), Table 4: The tissue weighting factor for gonads could be deleted. See Paragraph (68), (69) for explanation.

Paragraph (117): Up to now only adult male/female Voxel phantoms have been developed. Voxel phantoms for reference children are not yet available.

Paragraph (120): In formula (4.6) in both equations the right side must be divided by 13 (otherwise it is not the arithmetic mean as postulated above).

Paragraph (122): The 4th sentence should start "Operational dose equivalent quantities …".

Paragraph (123): The 1st sentence should start: "Effective dose conversion factors/coefficients (see general remark above) for external radiation exposure are calculated by Monte-Carlo simulations for standard conditions, …".

Paragraph (127): In formula (4.8) it is not clear that gender-averaged committed organ equivalent doses must be used.

Paragraph (128): In general it will not influence the committed doses very much but it should be reflected if the assumption of a life expectancy of 70 y is still adequate.

In the last sentence the foetus should be added.

Paragraph (131): In the last sentence it should be equation (4.9) not (1.9).

Paragraph (133): In formula (4.10) the summand 0.01Hp(0.07) should be added.

Paragraph (135): The 3rd sentence should read: The dose is not usually obtained by in vivo and in vitro measurements as for occupational exposure …" because due to the new terminology (for example ISO) direct measurements are called in vivo measurements and because also excretion measurements are unlikely for public exposure.

The difference between the estimation of doses of occupationally exposed persons (measurements) and the assessment of doses of members of the public (calculations) should be revealed more clearly.

Paragraph (136): delete “and therapeutic procedures” in second sentence. The effective dose does not make sense in radiation therapy due to the necessary high dose in the target area (cf. UNSCEAR). The last but one sentence should start "For the planning of diagnostic and therapeutic procedures for patients and risk-benefit assessments …".

Paragraph (137): The last sentence should be replaced: “Care has to be taken in such situations so that as reasonable as possible no tissue reactions occur.”

Paragraph (138): see Paragraph (136): The use of effective dose does not make sense in radiation therapy.

Paragraph (139): The 2nd sentence should read: "The calculation of effective dose or corresponding dose conversion coefficients for external exposure, …".

Paragraph (143): “Similarly, absorbed doses, not effective doses, are required for calculations of probability of causation of cancer in individuals.” See recommendation for Paragraph (17). How about equivalent dose for calculations of probability of causation ?

Paragraph (145): The special name used for the collective dose quantity should be changed from “man sievert” to “person sievert”. See change in paragraph (355) “Reference Man” to “Reference Person”. The last sentence “Since the intent of the…is included in Paragraph (147) and might be deleted here.

Paragraph (152) states “However, for prospective dose assessments and in particular for calculations of the effective dose in regulatory processes, the dosimetric models and parameter values that the Commission recommends for determining doses from quantitative information should be taken as reference models. These values have been fixed by convention and are therefore not subject to uncertainty. Equally the Commission considers that the dosimetric models and parameter values which are needed for the purpose of recommending dose limits or constraints are defined as reference data and, therefore, are not uncertain.”

In addition, at the end of paragraph (S6) of the Draft of Committee 4 Assessing Dose of the Representative Individual for the Purpose of Radiation Protection of the Public is written: “For example, dose constraints, weighting factors, and dose coefficients – when used in the process of assessing compliance and in decision making – are selected as fixed point values and are assumed not to be uncertain. The Commission, however, recognises that there are uncertainties in the models linking detriment to dose. These uncertainties are considered in establishing selected values of quantities such as limits and constraints.”
These statements are difficult to interpret. It would be helpful to outline which uncertainties (and/or variability in data and/or probability distributions) have been taken into account in deriving the various limits and constraints set for protection of the individual and how this was done (e.g. by safety factors, expert judgement, probabilistic assessments?).

Specifically in the context of probabilistic dose assessments, we would like to emphasize that taking into account individual variability in many of the quantities mentioned above (e.g. gender specific tissue weighting factors, dose coefficients) is essential to apply the new concept of the representative individual defined such that the probability is less than about 5 % that a person drawn at random from the population will receive a greater dose (para. (S17) of the Draft of Committee 4 Assessing Dose of the Representative Individual for the Purpose of Radiation Protection of the Public).

Moreover, quoting uncertainties of the quantities linking detriment to dose is not only good practice in science, but is also needed for retrospective assessments of exposure and risk of an individual or a known population.

5. The System of Radiological Protection of Humans

Paragraph (164): Since types of exposure are formulated as bullet points the same should be used for the categories of exposure.

Paragraph (172): see Paragraph (17). The first sentence is excellent.

Paragraph (173): In the forthcoming ICRP Committee 3 report on medical radiation one should deal with the radiation hygienic consequences of the so-called “radioiodine tourism” (treatment of patients with high activity radioiodine in one country and their moving uncontrolled to an other country).

Paragraph (175) indicates that the Commission has replaced its critical group concept to the new concept of using a so called representative individual for dose estimations. Details are given in the Draft of Committee 4 Assessing Dose of the Representative Individual for the Purpose of Radiation Protection of the Public. According to this draft, the representative individual shall be defined such that the majority (i.e. 95 %) of the population shall be protected to the degree given by the constraint. Up to 5% of the population may receive doses above the dose constraint.

This fundamental change in protection philosophy has to be based on convincing arguments, which are given neither in the Committee 4 draft nor in the Draft General Recommendations. In our opinion, such changes in the protection philosophy should be discussed in the ICRP general recommendation on radiation protection rather than in any of accompanying documents and would profit from a broad stakeholder involvement and discussion.

In addition, the use of a 95th percentile to decide on compliance with a constraint is questionable. As no rationale is given for this value, it seems to be taken from statistical hypothesis testing. It should be remembered, however, that (i) its use is nothing else but a convention between statisticians, (ii) that “statistical significance” is different from “relevance”.

As discussed in the Draft of Committee 4 Assessing Dose of the Representative Individual for the Purpose of Radiation Protection of the Public, the Commission proposes to reduce the number of age categories for the prospective calculation of dose for practices from six to three, while prospective calculations for emergency planning and all kind of retrospective dose assessments should still be based on six age categories (plus embryo and foetus).

One of the basic principles of our radiation protection system is that the additional health risk of an individual receiving a dose equal to the constraint or limit shall be almost identical for each member of the society, especially for each age group. It was this principle which motivated the ICRP nearly 20 years ago to develop age dependent dose coefficients for 6 age groups in order to implement the scientific evidence of age-dependent radiation risks (alternatively age-dependent values of limits or constraints could have been introduced).

The proposed reduction of number of age groups considered for prospective dose assessments and the introduction of a new set of averaged dose coefficients for three age groups represents an implicit change of philosophy that each individual should be protected at the same level of risk. Although we are aware of practical limitations, we do not see any rationale to modify the principle. On the contrary, the move (at least in many western societies) from utilitarian approaches, including risk perception, to a focus on the individual strongly favours the philosophy that regulations should reflect identical risks to all individuals.
If, however, the Commission has strong arguments to change its traditional principle of constraints representing identical risks to all individuals, this should be stated and outlined in the new General Recommendations. In our opinion, such a change should not be introduced in an accompanying document.

We would like to draw the Commission’s attention to the fact that for practical implementation in national legislation not much is gained with such a reduction of number of age groups as national procedures will still have to foresee dose assessments based on six age categories (plus embryo and foetus) for prospective calculations for emergency planning and all kind of retrospective dose assessments. In addition, countries of the European Union recently finalised the implementation of the EC directive 96/29/Euratom which stipulates the use of six age groups for dose assessment.

Paragraph (177): What is meant by “This should not be understood as an ethical position of the commission on the status of the foetus”?
Third sentence “It is the Commission´s policy… replace “members of the general public” by “for persons under 18 years”.
It is stated that "the methods of protection at work for women who are or may be pregnant should provide a level of protection for the fetus broadly comparable to that provided for members of the general public". This would imply an annual effective dose limit of 1 mSv for the foetus/newborn for the whole pregnancy (and the first 3 months of childhood). It is not necessarily valid that "this policy will be adequately applied if the mother is exposed, prior to her declaration of pregnancy, under the system of protection recommended by the Commission": Generally it might be possible that a foetus of an occupationally exposed mother receives a dose higher than 1 mSv even if the mother meets her dose limits and stops intakes after declaration of pregnancy. In the last but one sentence it is only demanded that the (effective?) dose to the foetus after declaration of pregnancy should not exceed about 1 mSv, there is no special limit for the early pregnancy up to their declaration.

Paragraph (179): It is not generally right that "for members of the public, the limit on effective dose means that the embryo/foetus is adequately protected…", see Par. 180 ("the dose to the offspring can exceed that of the reference adult by a factor of around 10").

Paragraph (185): The term “societal factors” should be elucidated.

Paragraph (210): There are two Tables 4. This Table should be number 5 and be moved next to page 56. The numbering of the following table must be adjusted.

Paragraph (215): Third sentence: “Members of the public supporting patients being…require individual consideration”. “Individual consideration” should be described in more detail by “guidelines taking also into account individual conditions.” The sentence “relevant constraints should be higher than those for general individuals” is not comprehensible, what does “general individual” exactly means ?

Paragraph (217): To maintain the values for constraints recommended in Publication 77 an 82 is acknowledged. These values are in agreement with those recommended by national advisory bodies (SSK; RSK).

Paragraph (230): However in paragraph (147) “collective dose is not intended as a tool for epidemiologic risk assessment”, now “…limitations in the use..”. This paragraph might be deleted because most is already written in other parts of the draft.

Paragraph (240): In Table 5 “Recommended dose limits” additional limits should be added for doses to the thyroid and to the foetus during pregnancy.

Paragraph (242): There is an explanation necessary for the 10 times lower dose limits for lens, skin and extremities for the public compared to radiation workers. The goal is to avoid radiation reactions. The threshold doses are the same for the public and workers.

6. Medical Exposure of Patients

Paragraph (244): The first sentence is excellent. Here, the issue of radiation exposure resulting from “radioiodine tourism” should be dealt with as well.

Paragraph (254): The sentence “the selected values will be specific to a country or region” is excellent.

Paragraph (256): The statement about levels is excellent.

Paragraph (259): There is full consent with the statement, in particular with the first and the last sentence.

Paragraph (260): The currently valid threshold values should be referred to in the first sentence.

Paragraph (264): Including pregnant women in pharmacological research is discussed and handled controversially. The Helsinki Declaration and GCP (Good Clinical Practice) should be referenced as well.

Paragraph (269): Radiation exposures for insurance purposes should not be permitted. Already available medical records are sufficient.

7. Exposure of Natural Sources

Paragraph (285): The world dose rate is given as 0.3 – 0.6 mGy, however the average is written in mSv.

Paragraph (300): The recommendation of a effective dose of 10 mSv per year as a radon action level is not substantiated. Radiation protection authorities worldwide (see EPA, Swiss BAG) consider lower levels either by reviewing the population attributable lung cancer risk by radon or the radon concentration in open air of about 40 to 60 Bq/m3. National considerations might indicate lower Action levels than proposed by the Commision. It should be emphasised, that the constraints for radon-222 (Tab. 6) are meant as levels where action is absolute necessary. Lower Action Levels e.g. set by national regulations should be recommended. There should be a differentiation between existing situations (e.g. older houses) and planned situations (e.g. building new houses, constraint 100 Bq m-3).

8. Potential Exposures

Paragraph (315), line 6: misprint …some…

Paragraph (318): The generic risk constraint should be given as a yearly or life time risk.
The citation must be (ICRP a, 1998) or (ICRP b, 1998).

Paragraph (332): Individual accidents should not be quoted. The selection is one-sided here, not only with respect to geography or health care level. For radiation therapy typical scenarios might be represented that have been made anonymously, like wrong doses resulting from software faults or wrong data input. World-wide statistics about such accidents might be referenced.

9. Emergency Situations and Existing Situations

Various statements and recommendations of identical or different nature and content can be found in different parts of the draft, ie for emergency situations in sections 5.7, 5.8, 6.1. 6.4, 9.4, 9.5; and for existing situations in sections 5.7, 5.8, 7.2, 7.4, 8.4. This makes the reading of the draft difficult and there is the danger to confuse the reader. A consolidation of the text is urgently needed.

An important aspect of protection in emergency situations is the lifting of countermeasures. Publication 63 and the new draft don’t say anything about this at all. ICRP should develop guidance and recommendations how to deal with this issue.

Paragraph (337) states that ‘the first concern…is to keep the exposure to individuals…below thresholds for severe deterministic health effects’. In the past, ICRP has associated this level with 500 mSv/mGy. IAEA is proposing 100 mSv as a constraint for foetus exposure and 1 Gy-Eq as a constraint for brief external exposure of the adults (therefore, taking into account the need of providing protection for the most sensitive member of the public – in this case, the foetus, 100 mSv is proposed by IAEA as a generic constraint). ICRP’s dose constraint of 100 mSv in one year would appear to replace these criteria. However, there is a separate issue of local organ exposure (e.g. soft tissue) which is not addressed by applying proposed ICRP constraint of 100 mSv in one year. With the current suggested dose constraint of 100 mSv, this leaves a ‘gap’ between the requirement to avoid severe deterministic injuries and the requirement to limit stochastic health consequences. This could result in an apparent conflict between the two requirements for protection, with a possible outcome that the needs of those at risk of suffering deterministic injuries are not afforded sufficient priority. ICRP should develop emergency planning dose thresholds to support planners in meeting this requirement.

Paragraph (338): ICRP argues for 100 mSv on the basis of three claims (para 202): that the linear dose-response relationship is really only valid up to 100 mSv; that above 100 mSv there is an increased likelihood of tissue reactions; that a significant excess of cancers have been identified in populations exposed to doses of around 100 mSv/y. In para 338, ICRP re-states that it ‘now considers…100 mSv’ to be a level of dose ‘approaching that which would cause tissue reactions’. With regard to observed cancers this seems to apply only to continuing exposure at 100 mSv/y not for one-off exposures. This issue needs clarification.

Paragraph (339) appears to re-confirm the numerical values of the intervention levels given in Publication 63. For evacuation, the upper intervention level is given as 500 mSv averted effective dose. It is not straightforward to reconcile these two numbers for upper dose constraints, i.e. 100 mSv total projected dose and 500 mSv averted dose. As a consequence, the last sentence of para.339 “The intervention levels given in those publications are now regarded as constraints.” should be deleted. It is not clear how to deal with constraints for organ dose (e.g. thyroid, lung), as the constraints are currently expressed in terms of effective dose only. These issues need clarification.

Paragraph (346) of the draft of the new ICRP recommendation states ‘Justification of an intervention should begin by considering the average projected dose to the exposed population to which the intervention would be applied’. Averaging dose over all those who might, eg, be sheltered, could mean averaging over a very wide range of doses. This could result in a highly non-optimum solution, and, in particular, insufficient protection for those most at risk. Para. 346 goes on to say that ‘if protective action is not justified, consideration should be given to…subgroups’. What planners more naturally do is to consider discrete groups of people who are similar in most respects, including their likely exposures, where they live or are located, the ease with which the countermeasure can be applied to them, etc, and then optimise their protection explicitly. After all such groups have been considered consideration is given to sorting out issues of applying the combination of countermeasures (eg evacuating a small group of people who would otherwise have been sheltered, because this was already being planned for a larger, neighbouring group). This approach is much more like identifying a series of representative individuals than the approach set out in para 346.

10. Protection of the Environment

Paragraph (357): Line 9 should read: “recognises that the framework now developing for non-human species needs to…”

11. Implementation of the Commission´s Recommendations

Glossary

Generally very often the term "radiation-weighted dose" is used instead of "equivalent dose"!

Editorial issues: some special signs are not printed correctly.

Alpha/Beta ratio: The ratio is applied also for other biological endpoint besides cell killing.

Biological Half-Life. In ICRP publications the term "biological half-time" is used instead. On the other hand in this document this term is not used and can be omitted in this glossary.

Collective Effective Dose, S. This definition is rather long, partly it could be revised to the text.

Derived Air Concentration (DAC). In formula (5.8) of the dosimetry document the gender-averaged volume of air inhaled in a working year of 2200 m³ is used instead of the male value 2400 m³ which is used here. On the other hand in this document this term is not used and can be omitted in this glossary.

Effective Dose, E. A formula before the "or" seems to be missing.

Intake, I. Also other intake pathways (wound, intact skin, injection in nuclear medicine) should be considered here.

Particle Fluence, Φ. In this document this term is not used and can be omitted in this glossary.

Quality Factor, Q is missing.

Source Region {Si} is missing.

Specific Absorbed Fraction. It might be better to write "… which is absorbed per unit mass of a target tissue (kg-1)". The present formulation "… is absorbed in 1 kg of a target tissue" is difficult to imagine – that would be 50 thyroids of the reference man for example.

Target Region {Ti}. The contents of the gastrointestinal tract or urinary bladder are not radiation-sensitive and should not be considered as target regions.