Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This is a well-structured, informative, and clearly written manuscript.

 Some minor revisions are suggested here: 

The Title may be refined as "Airborne Radioiodine-131: A Comparative Review of Chemical Forms in Medicine, Industry, and Fallout"

Abstract:  The transition from medical to industrial contexts is good, but the sentence about "exhaled activity... is minimal" could be slightly rephrased to more immediately highlight the contrast with its chemical form. It may be changed to "Although the total exhaled activity after medical I-131 therapy is minimal, over 95% of this activity is in volatile organic forms..." This small change emphasizes that despite the low quantity, its nature is what matters.

Consider breaking the long sentence about Chernobyl and Fukushima into two for easier parsing, i.e.,  "While routine reactor emissions yield negligible doses (<0.1 µSv/year), severe nuclear incidents like Chernobyl and Fukushima have caused thyroid doses ranging from tens of millisieverts to several Sieverts—particularly in children" should read as  "While routine reactor emissions yield negligible doses (<0.1 µSv/year), severe nuclear incidents like Chernobyl and Fukushima have resulted in significant thyroid exposures. Doses from these events ranged from tens of millisieverts to several Sieverts , particularly in children."

Lines 35-43: This paragraph should read "This review synthesizes evidence to demonstrate that chemical speciation is paramount. In the medical context, exhaled iodine is predominantly organic. During routine reactor operation, levels are negligible and effectively controlled. In major accident scenarios, however, releases are dominated by elemental and organic iodine, whose chemical nature dictates environmental transport and human exposure. This review integrates evidence from medicine, routine operation, and large-scale releases to demonstrate how chemical speciation governs volatility, environmental behaviour, and bioavailability. "

1. Introduction:

Lines 72-74: This sentence is slightly awkward. It should read "Since iodine isotopes are accumulated almost exclusively in the thyroid gland, it is the critical organ-at-risk for radioiodine exposure."

2. Radioiodine Isotopes Relevant to Different Scenarios

Line 107: The phrase "high incorporation" should read "and its high thyroid uptake fraction."

Line 111-113: The statement about I-129 could be made even more impactful. The clause "the mass required... is orders of magnitude higher than the gland’s physiological iodine capacity" is key. To strengthen it, you could add: "...making it a concern only for long-term environmental tracing and chronic low-dose exposure, not for acute radiation protection."

 3. Chemical Form Matters: Mechanisms and Representative Reactions

Lines 121-129 should read “The chemical behavior of airborne radioiodine (denoted as "I," with I-131 implied throughout) defies conventional textbook iodine chemistry. In medical, industrial, and reactor-accident environments, it is governed by a unique superposition of processes: aqueous redox, radiolytic radical pathways, thermal decomposition, and heterogeneous surface reactions. Under severe accident conditions, this expands to include high-temperature gas-phase transformations and combustion-induced radical chemistry. Together, these coupled processes yield iodine species fundamentally different from those formed under ambient laboratory conditions”.

4. Pathways of Incorporation and Systemic Distribution of Airborne 197 [¹³¹I]Iodine

Lines 218-231 should read “ Soluble aerosol salts like [¹³¹I]CsI dissolve readily in the airway lining fluid, releasing ionic [¹³¹I]⁻, which is efficiently absorbed into the bloodstream and taken up by the thyroid.

In contrast, some airborne radioiodine can become incorporated into or adsorbed onto particulate matter of varying solubility. As outlined in ICRP Publications 60 and 119, pulmonary clearance of inhaled materials is governed primarily by their dissolution rate in lung fluids. These materials are categorized as absorption type F (fast), M (moderate), or S (slow) [12,45].

Rapidly dissolving (Type F) species are cleared within hours to days. Sparingly soluble or refractory (Type S) aerosols, however, may persist in the alveolar region for weeks to months before macrophage-mediated removal. For instance, aerosols where iodine is associated with mineral or metallic matrices may initially behave as Type S materials. Such particles contribute primarily to a localized pulmonary dose rather than to systemic irradiation.

 

5. Airborne ¹³¹I in practice: nuclear medicine, routine reactor operation, 381 and accidents

The concept that organic iodides are less efficiently filtered and more volatile is repeated multiple times (e.g., in 5.1, 5.2, 5.4, 5.5). While reinforcement is good, the phrasing is often very similar. The authors may vary the language. Instead of "less efficiently captured," use terms like "more challenging to scrub," "exhibit higher penetration," or "possess greater environmental mobility." Establish this as a key principle early on and refer back to it succinctly.

Specific Line Edits for Precision and Impact

Line 381-382: "in practice" is slightly vague. Consider: "Airborne ¹³¹I: Practical Manifestations Across Contexts" or "…: From Medical Use to Severe Accidents".

Line 390-391: "can pass... largely unretained" is clunky. Use: "largely penetrate conventional ventilation filters" or "are poorly retained by...".

Line 423-424: "remains dominated by" is good. To strengthen: "The chemical speciation of residual iodine near plant stacks is consistently dominated by...".

Line 495:  Consider expanding it to frame the entire subsection: "These four events provide a contrasting study in how reactor design, failure mode, and containment integrity dictate the magnitude and chemistry of iodine release, with direct consequences for public health."

7. Conclusion:

Lines 676-680 should read "Airborne radioiodine embodies the dual nature of modern nuclear science: it serves as a cornerstone of life-saving medical therapy while simultaneously posing a persistent challenge in nuclear safety."

Lines 681-686 should read "Our analysis demonstrates that the critical factor across all contexts is chemical form. In medicine, where exhaled activity is minute, the predominance of organic species defines the exposure risk. Similarly, in nuclear facilities, it is the volatile organic iodides that challenge even advanced filtration systems. This principle reaches its most severe expression in catastrophic events, where the chemical speciation of the released iodine directly dictated the scale of public health impact."

Lines 687-688 should read “This chemical dependency is universal. The same oxidative and radiolytic principles that govern iodine behaviour in reactor environments are also at work within the human thyroid. In both a damaged reactor core and a living gland, radiation and reactive oxygen species drive the conversion of iodide into volatile species, linking these extremes through a shared chemistry”

Line 695-696 should read “Therefore, effective protection and the responsible use of radioiodine demand a paradigm shift: from a primary focus on quantifying total activity to a deeper, more fundamental understanding and management of its chemistry. Ultimately, controlling the consequences of iodine-131 means controlling its chemical form."

Comments on the Quality of English Language

No major issue with the quality of English

Author Response

Response to Reviewer 1’s Comments on
“Airborne Radioiodine: A Comparative View of Chemical Forms in Medicine, Nuclear Industry, and Fallout Scenarios”

We sincerely thank the reviewer 1 for the careful, constructive, and insightful evaluation of our manuscript. The comments provided were highly valuable and have led to substantial improvements in clarity, structure, and conceptual focus, particularly in the Abstract, Section 5, and the Conclusion. All revisions requested by the reviewer have been fully implemented. For ease of review, all corresponding changes in the revised manuscript are highlighted in yellow.

Reviewer comment:
“The transition from medical to industrial contexts is good, but the sentence about 'exhaled activity… is minimal' could be slightly rephrased to more immediately highlight the contrast with its chemical form. It may be changed to: ‘Although the total exhaled activity after medical I-131 therapy is minimal, over 95% of this activity is in volatile organic forms…’”

Authors’ response:
We thank the reviewer for this helpful suggestion. We agree that highlighting the contrast between the low quantity of exhaled activity and its predominantly organic chemical form improves the clarity and emphasis of the Abstract. We have revised the sentence accordingly to read:

“Although the total exhaled activity after medical I-131 therapy is minimal, over 95 % of this activity appears in volatile organic forms.”

This modification strengthens the intended message and aligns with the reviewer’s recommendation.

Reviewer comment:
“Consider breaking the long sentence about Chernobyl and Fukushima into two for easier parsing…”

Authors’ response:
We thank the reviewer for this helpful stylistic suggestion. We agree that dividing the original sentence improves readability and emphasizes the quantitative contrast between routine releases and severe accidents. We have revised the text accordingly. The updated version now reads:

“While routine reactor emissions yield negligible doses (<0.1 µSv/year), severe nuclear incidents like Chernobyl and Fukushima have resulted in significant thyroid exposures. Doses from these events ranged from tens of millisieverts to several Sieverts, particularly in children.”

Reviewer comment:
“Lines 35–43: This paragraph should read …”

Authors’ response:
We thank the reviewer for this very clear and helpful suggestion. We agree that the concluding paragraph of the Abstract benefits from a more concise and structured formulation emphasizing the central role of chemical speciation. We have therefore replaced the original paragraph with the reviewer’s proposed wording, with minor stylistic adjustments for consistency with the manuscript. The revised paragraph now reads:

“Chemical speciation is the key determinant across all scenarios. Exhaled iodine in medicine is predominantly organic; routine reactor releases are negligible; severe accidents predominantly release elemental and organic iodine that drive environmental transport and exposure. Integrating these domains shows how chemical speciation governs volatility, mobility, and bioavailability.”

Reviewer comment:
“Lines 72–74: This sentence is slightly awkward. It should read ‘Since iodine isotopes are accumulated almost exclusively in the thyroid gland, it is the critical organ-at-risk for radioiodine exposure.’”

Authors’ response:
We thank the reviewer for this helpful suggestion. We have revised the sentence in the Introduction accordingly. The updated version now reads:

“Since iodine isotopes are accumulated almost exclusively in the thyroid gland, it is the critical organ-at-risk for radioiodine exposure.”

Reviewer comment:
“Line 107: The phrase ‘high incorporation’ should read ‘and its high thyroid uptake fraction.’”

Authors’ response:
We thank the reviewer for this helpful clarification. The term “thyroid uptake fraction” is indeed more precise in the radiological context. We have revised the sentence accordingly. The updated version now reads:

“From a radiological perspective, I-131 remains the dominant contributor to thyroid dose over a wide area after accidental releases because of its intermediate half-life, high cumulative yield, and its high thyroid uptake fraction.”

Reviewer comment:
“Line 111–113: The statement about I-129 could be made more impactful… add: ‘…making it a concern only for long-term environmental tracing and chronic low-dose exposure, not for acute radiation protection.’”

Authors’ response:
We thank the reviewer for this helpful suggestion. We agree that specifying the radiological relevance of I-129 enhances clarity. We have therefore extended the sentence accordingly. It now reads:

“By contrast, I-129, despite its extremely long half-life and relatively high per-Bq dose coefficient, is practically irrelevant for acute dose considerations: the mass required to achieve MBq activities in the thyroid is orders of magnitude higher than the gland’s physiological iodine capacity, making it a concern only for long-term environmental tracing and chronic low-dose exposure rather than for acute radiation protection.”

Reviewer comment:
“Lines 121–129 should read: ‘The chemical behavior of airborne radioiodine (denoted as "I," with I-131 implied throughout) defies conventional textbook iodine chemistry… etc.’”

Authors’ response:
We thank the reviewer for this improved formulation. We agree that the proposed structure enhances clarity and readability while preserving the mechanistic detail of this section. We have therefore replaced the original paragraph with the reviewer’s suggested wording, with minimal stylistic adjustments for consistency. The revised text now reads:

“The chemical behavior of airborne radioiodine (denoted as ‘I,’ with I-131 implied throughout) defies conventional textbook iodine chemistry. In medical, industrial, and reactor-accident environments, it is governed by a unique superposition of processes: aqueous redox reactions, radiolytic radical pathways, thermal decomposition, and heterogeneous surface reactions. Under severe accident conditions, this expands to include high-temperature gas-phase transformations and combustion-induced radical chemistry. Together, these coupled processes yield iodine species fundamentally different from those formed under ambient laboratory conditions.”

Reviewer comment:
“Lines 218–231 should read ‘Soluble aerosol salts like [¹³¹I]CsI dissolve…’”

Authors’ response:
We thank the reviewer for this improved and more clearly structured formulation. The suggested wording enhances readability and aligns well with the established ICRP classification framework. We have therefore replaced the original paragraph with the reviewer’s text, with only minimal stylistic adjustments for consistency. The revised passage now reads:

“Soluble aerosol salts like [¹³¹I]CsI dissolve readily in the airway lining fluid, releasing ionic [¹³¹I]⁻, which is efficiently absorbed into the bloodstream and taken up by the thyroid. In contrast, some airborne radioiodine can become incorporated into or adsorbed onto particulate matter of varying solubility. As outlined in ICRP Publications 60 and 119, pulmonary clearance of inhaled materials is governed primarily by their dissolution rate in lung fluids. These materials are categorized as absorption type F (fast), M (moderate), or S (slow) [12,45]. Rapidly dissolving (Type F) species are cleared within hours to days. Sparingly soluble or refractory (Type S) aerosols, however, may persist in the alveolar region for weeks to months before macrophage-mediated removal. Aerosols in which iodine is associated with mineral or metallic matrices may initially behave as Type S materials. Such particles contribute primarily to a localized pulmonary dose rather than to systemic irradiation.”

Reviewer comment (Section 5):
“The concept that organic iodides are less efficiently filtered and more volatile is repeated multiple times (e.g., in 5.1, 5.2, 5.4, 5.5). While reinforcement is good, the phrasing is often very similar. The authors may vary the language. Establish this as a key principle early on and refer back to it succinctly.”

Authors’ Response:
We thank the reviewer for this helpful stylistic and structural suggestion. We agree that repeated phrasing can be streamlined.

Accordingly, the wording in Section 5.2 has been revised to read:

“Although [¹³¹I]CH₃I is intrinsically more challenging to remove by conventional activated-charcoal or silver-impregnated filtration systems than [¹³¹I]I₂ or [¹³¹I]HOI, its contribution to the total iodine-131 inventory in stack effluents remains negligible under normal operating conditions.”

Further corresponding wording adjustments have been implemented in the remaining subsections of Section 5 to ensure consistent terminology and to avoid repetitive phrasing.

In Section 5.3, the corresponding sentence has been rephrased to avoid parallel “Although …” openings with the adjacent subsection and to emphasize retention and scrubbing efficiency in a distinct wording. The revised sentence now reads:

“The magnitude of such releases is typically orders of magnitude lower than during full core damage or accident scenarios; nevertheless, the released species often include iodide-131 ([¹³¹I]I⁻) in aqueous form as well as volatile molecular iodine ([¹³¹I]I₂) or organic iodides, whose retention depends on gap chemistry and the efficiency of available scrubbing processes.”

In Section 5.4, the wording has been revised to avoid repetitive formulations and parallel sentence openings used in adjacent subsections. The revised sentence now reads:

“Absolute ¹³¹I discharges are typically small, on the order of <10⁻⁸ Bq per batch; nevertheless, efficient capture systems and continuous monitoring remain necessary, as organoiodine vapors exhibit higher penetration through conventional filtration systems than molecular iodine.”

We thank the reviewer for the detailed and constructive suggestions regarding the Conclusion section. We agree that these proposed revisions significantly improve clarity, focus, and conceptual coherence. The revised Conclusion more clearly articulates the central message of the review and strengthens the synthesis across medical, industrial, and accident-related contexts.

In the Conclusion (lines 676–680), the opening statement has been revised for improved clarity and impact. The revised sentence now reads: “Airborne radioiodine embodies the dual nature of modern nuclear science: it serves as a cornerstone of life-saving medical therapy while simultaneously posing a persistent challenge in nuclear safety.”

In the Conclusion (lines 681–686), the original paragraph was replaced with the reviewer’s proposed wording to sharpen the cross-context synthesis and to state the central message more explicitly. The revised paragraph now reads: “Our analysis demonstrates that the critical factor across all contexts is chemical form. In medicine, where exhaled activity is minute, the predominance of organic species defines the exposure risk. Similarly, in nuclear facilities, it is the volatile organic iodides that challenge even advanced filtration systems. This principle reaches its most severe expression in catastrophic events, where the chemical speciation of the released iodine directly dictated the scale of public health impact.”

In the Conclusion (lines 687–688), the original sentence was replaced with the reviewer’s proposed formulation to more explicitly highlight the shared oxidative and radiolytic mechanisms underlying iodine speciation in both reactor environments and the human thyroid. The revised text strengthens the conceptual link between medical and accident scenarios by emphasizing a common chemical basis rather than treating these contexts separately.

In the Conclusion (lines 695–696), the final sentence of the manuscript was replaced with the reviewer’s proposed wording. This revision reframes the closing statement to emphasize the need for a paradigm shift from activity-based metrics toward a chemistry-centered perspective, thereby reinforcing the central conclusion of the review.

Reviewer 2 Report

Comments and Suggestions for Authors

Manuscript Title: Airborne Radioiodine: A Comparative View of Chemical Forms in Medicine, Nuclear Industry, and Fallout Scenarios

Dear Authors,

This manuscript provides a broad overview of airborne radioiodine speciation across medical, industrial, and severe-accident contexts. The cross-scenario perspective is valuable, and the topic is relevant for nuclear medicine, reactor safety, and environmental radiological protection. The paper is generally well organized and supported by extensive literature. However, several issues must be addressed before the manuscript is suitable for publication.

Major Comments

1. Scope and novelty: The review is comprehensive but does not clearly articulate its novel contribution. Large portions of it summarize established iodine chemistry without offering sufficient critical synthesis. The authors should better highlight what is new, comparative, or integrative about their approach.
2. Redundancy and clarity: Several concepts (especially the analogy between thyroid and reactor chemistry) are repeated in multiple sections. Section 3 is dense and mechanistically overloaded, making it difficult for reading for non-specialists. The narrative would benefit from clearer structuring and removal of repetitive elements.
3. Quantitative context: For a “comparative” review, quantitative contrasts across medical, routine-release, and accident scenarios are limited. The authors should for example, include more numerical ranges (e.g., relative fractions of I₂, HOI, CH₃I; typical emission rates) where available.
4. Overinterpretation of medical emissions of iodine: The manuscript suggests that exhaled organic iodine species may be radiologically significant, but the evidence remains limited and highly context-dependent. This section requires more cautious framing and clearer distinction between biochemical insight and public-exposure relevance.
5. Integration of chemistry and dosimetry: The authors describe atmospheric speciation and thyroid dosimetry separately but does not fully integrate them. A more explicit discussion of how physicochemical form translates into dose differences would strengthen the review’s central thesis.

Minor Comments

• Terminology for organic iodine species is inconsistent (e.g., “organified iodine,” “organic iodides,” “organic fraction”). Standardize throughout.
• Tables are informative but extremely long and dense; authors could consider simplifying or reorganizing them for enhance readability.
• The Abstract is maybe too long and repetitive (for example, nuclear incidents Chernobyl and Fukushima are mentioned twice), and includes concluding statements that should be moved to the Discussion.
• Introduction of a conceptual figure integrating cross-scenario pathways would enhance readability of the text.

Author Response

Response to Reviewer 2’s Comments on
“Airborne Radioiodine: A Comparative View of Chemical Forms in Medicine, Nuclear Industry, and Fallout Scenarios”

 

Reviewer’s comment:
“Scope and novelty: The review is comprehensive but does not clearly articulate its novel contribution. Large portions of it summarize established iodine chemistry without offering sufficient critical synthesis. The authors should better highlight what is new, comparative, or integrative about their approach.”

Authors’ response:
We thank the reviewer for this thoughtful and constructive comment. We agree that, while the comparative and integrative nature of the review was inherent to its structure, the novelty of the approach was not stated with sufficient explicitness in the original version. The intent of the review is not to introduce new iodine chemistry, but to provide a systematic comparative synthesis across medical, industrial, and accident-related contexts that are usually addressed separately.

To address this point, we have now explicitly articulated the novel contribution of the review at two key locations in the manuscript.

Revisions implemented in the manuscript:
First, the Abstract has been revised to include a clear and explicit novelty statement. It now reads:
“The novelty of this review lies not in introducing new iodine chemistry, but in the systematic comparative synthesis of airborne radioiodine speciation across medical therapy, routine nuclear operation, and severe accident scenarios, identifying chemical form as the unifying determinant of volatility, environmental transport, and dose.”

Second, a dedicated paragraph has been added to the end of the Introduction to explicitly articulate and contextualize the novel contribution of the review. This paragraph reads as follows:

“While numerous studies and reviews have addressed iodine chemistry in medical applications, routine reactor operation, or severe nuclear accidents individually, these domains are typically treated in isolation. A systematic comparison across these contexts is largely lacking, despite the fact that the underlying chemical and radiolytic processes governing iodine speciation are closely related. The present review does not aim to introduce new iodine chemistry; rather, its novelty lies in the explicit comparative synthesis of airborne radioiodine behavior across medicine, nuclear industry, and accident scenarios. By integrating these perspectives, the review identifies chemical form as the unifying determinant of volatility, environmental transport, and dose, thereby providing a coherent framework that links clinical practice, nuclear safety, and radiological protection.”

Comment on scope, clarity, and integration (Conclusion)

Authors’ response:
We thank the reviewer for the thoughtful comments regarding clarity, integration, and emphasis in the concluding section. We have taken this feedback seriously and initially revised the Conclusion to more explicitly reflect the comparative and integrative contribution of the review.

During the subsequent revision process, and in light of additional comments from another reviewer, it became apparent that further restructuring was necessary to avoid redundancy and to ensure a clear and technically precise distinction between different exposure pathways. The Conclusion has therefore been comprehensively revised and streamlined to improve coherence, to eliminate overlapping formulations, and to more accurately reflect the role of chemical speciation across medical, industrial, and accident-related contexts.

We believe that this consolidated revision addresses the reviewer’s concern while enhancing clarity and readability of the manuscript as a whole.

Reviewer`s Comment

Redundancy and clarity: Several concepts (especially the analogy between thyroid and reactor chemistry) are repeated in multiple sections. Section 3 is dense and mechanistically overloaded, making it difficult for reading for non-specialists. The narrative would benefit from clearer structuring and removal of repetitive elements.

 

Authors’ response:

We thank the reviewer for this thoughtful and constructive comment regarding redundancy and clarity.

We acknowledge that Section 3 revisits closely related chemical mechanisms, including analogies between biological iodine processing and reactor associated iodine chemistry. This recurrence is intentional and reflects the central message of the section, namely that identical or closely related chemical pathways reappear across fundamentally different environments when comparable physicochemical constraints apply.

To improve clarity and accessibility for non specialist readers, Section 3 has been substantially restructured. Mechanistic details that previously appeared repeatedly in the text have been consolidated into a set of scenario specific summary tables (Tables 2A to 2D). This allows similar reactions to be compared explicitly across contexts, while the accompanying text has been streamlined to reduce density and repetition.

In addition, the concluding paragraphs following Table 3 have been carefully revised and streamlined to further clarify the central narrative of Section 3 and to explicitly summarize its unifying mechanistic concept before the transition to Section 4.

 

Reviewer`s Comment
Quantitative context: For a “comparative” review, quantitative contrasts across medical, routine-release, and accident scenarios are limited. The authors should for example include more numerical ranges (e.g., relative fractions of I₂, HOI, CH₃I; typical emission rates) where available.

Authors’ Response
We thank the reviewer for this comment and for highlighting the issue of quantitative context.

A comprehensive and quantitatively consistent compilation of iodine speciation data, particularly for major nuclear accidents, would indeed require an extensive re-evaluation of a highly heterogeneous literature. Even for well-documented events such as Chernobyl or Fukushima, reported speciation data vary widely depending on accident phase, sampling location, analytical methodology, and modelling assumptions. As a result, assembling precise percentage distributions across studies is not only labor-intensive but also associated with substantial uncertainty and limited comparability.

More importantly, the scientific benefit of such detailed percentage values is inherently limited with respect to the central question of radiological relevance. Knowledge of the exact fractional distribution of I₂, HOI, or CH₃I in the atmosphere does not, by itself, translate into a better understanding of thyroidal uptake, internal dose, or long-term health outcomes. These endpoints are governed by subsequent biological processing and biokinetics, for which robust epidemiological and dosimetric data already exist, including well-established correlations between radioiodine exposure and thyroid disease, particularly childhood thyroid cancer.

For this reason, the present review deliberately emphasizes mechanistic pathways, dominant chemical drivers, and their implications for atmospheric behavior and biological availability, rather than exhaustive numerical partitioning of iodine species. We believe that this focus better reflects the aspects of radioiodine chemistry that are most relevant for health risk assessment and clinical consequences.

Reviewer`s Comment
Overinterpretation of medical emissions of iodine: The manuscript suggests that exhaled organic iodine species may be radiologically significant, but the evidence remains limited and highly context-dependent. This section requires more cautious framing and clearer distinction between biochemical insight and public-exposure relevance.

Authors’ Response

We thank the reviewer for this comment. To address this point, we have revised Section 5.1 by explicitly clarifying the interpretative scope of the findings on exhaled organic radioiodine. A sentence has been added immediately following the discussion of modeled exposure scenarios to emphasize that these observations primarily provide biochemical and mechanistic insight at the individual level and should not be interpreted as indicating a relevant contribution to public radiation exposure. We hope that this clarification adequately addresses the reviewer’s concern.

Reviewer`s Comment
Integration of chemistry and dosimetry: The authors describe atmospheric speciation and thyroid dosimetry separately but does not fully integrate them. A more explicit discussion of how physicochemical form translates into dose differences would strengthen the review’s central thesis.

Authors’ Response

We thank the reviewer for this comment. We would like to point out that the relationship between physicochemical iodine form and resulting dose differences is already explicitly addressed in Section 4. In this section, different chemical forms and uptake pathways are quantitatively linked to thyroid dose coefficients based on established ICRP models (including Table). We therefore believe that the requested integration of chemistry and dosimetry is already clearly and quantitatively presented in the current manuscript.

Minor Comments

Reviewer`s Comment

Terminology for organic iodine species is inconsistent (e.g., “organified iodine,” “organic iodides,” “organic fraction”). Standardize throughout.

Authors’ Response

We thank the reviewer for noting this point. The terminology has been standardized throughout the manuscript by consistently using the term organic iodine  instead of organified iodine. We believe this improves clarity and consistency of the nomenclature across all sections.

Reviewer`s Comment

Tables are informative but extremely long and dense; authors could consider simplifying or reorganizing them for enhance readability.

Authors’ Response

We thank the reviewer for this comment. In response, we have reorganized the originally comprehensive Table 2 by subdividing it into four scenario-specific tables (Tables 2A–2D). This restructuring preserves the full informational content while substantially improving readability and alignment with the narrative structure of Section 3. We believe that this modification directly addresses the reviewer’s concern and enhances clarity for the reader.

Reviewer`s Comment

The Abstract is maybe too long and repetitive (for example, nuclear incidents Chernobyl and Fukushima are mentioned twice), and includes concluding statements that should be moved to the Discussion.

Authors’ Response

We thank the reviewer for this comment. To reduce redundancy in the Abstract, we have streamlined the wording and removed the explicit repetition of individual accident names. The relevant sentence now refers more generally to major nuclear accidents, while preserving the intended emphasis on the chemical form and volatility of released iodine.

As this manuscript is a review article, the Abstract is intended to provide a concise synthesis of both scope and key conclusions. We therefore retained the integrative statements that guide the comparative framework developed in the main text.

Reviewer`s Comment

Introduction of a conceptual figure integrating cross-scenario pathways would enhance readability of the text.

Authors’ Response

We appreciate this constructive suggestion. The cross-scenario integration of chemical pathways is currently conveyed through the combined presentation of Tables 2A–D, Table 3, and the concluding synthesis at the end of Section 3, which together serve as a structured conceptual framework.

While a graphical representation could provide an alternative visualization, we believe that the existing tabular and textual integration allows for a more explicit and detailed comparison of mechanisms across scenarios without oversimplification. We therefore chose to retain the current format, which emphasizes mechanistic clarity and traceability to the underlying literature.

We thank Reviewer 2 for the thoughtful comments. Revisions addressing these points are highlighted in light blue in the revised manuscript to allow for easy identification of the modified text.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The revised version of the manuscript is suitable for publication.