Occupational Exposure to Mineral Dust in Mining and Earthmoving Works: A Scoping Review

Round 1

Reviewer 1 Report

Manuscript ID: safety-1480406

Review

This review intends to identify conditions under which occupational exposure to mineral dust occurs, mostly in mining given that most available studies are restricted to this activity. Given that dust concentrations available in the literature of dust in the context of such activities were obtained under very different methodologies, the authors are not able to obtain quantitative results, or even robust qualitative results. In this sense, the conclusions obtained in this study do not represent an important contribution to the topic. However, the review itself was performed adequately, and the lack of useful results is fully due to the nature of available studies. In any case, the main conclusion from this manuscript is that a protocol is required for this kind of studies, a conclusion that was already reached by other authors (see reference [7] from this manuscript). One question is thus whether a review on this topic was warranted. The main reason for a positive answer on this question is that this review makes the necessity of a standard protocol even more evident. I recommend publishing this manuscript on Safety, provided some minor revisions are considered.

Minor revisions (see also annotated revisions)

lines 28-29: requires a reference, for example: Karanasiou, A., Moreno, N., Moreno, T., Viana, M., de Leeuw, F., & Querol, X. (2012). Health effects from Sahara dust episodes in Europe: literature review and research gaps. Environment international, 47, 107-114.

lines 45-48: I do not see the point of this paragraph. I believe it does not add any valuable information, and it breaks the connection between the preceding and the next paragraphs. I recommend eliminating it.

lines 56-57: the source of this information needs to be stated.

line 66: Is the objective of this sentence to state that coal is the commodity whose mining leads to the greatest rise in lung disease cases? If so, this sentence should be re-written for greater clarity. I suggest: "..., leading the rise in new cases of lung disease, ...".

lines 108-112: it should be briefly mentioned why you chose those databases/journals.

lines 142-150: it is not clear what is meant by "the risk of bias within studies". It seems to refer to whether each defined parameter has an effect on results or not. Please, state what you mean by "risk of bias", as "bias" may be defined in very different ways. Also, at this point in the text, the reader does not know what results will be analyzed. Is it dust concentration? Please, be more specific here. Finally, one of the categories of the analyzed parameters is "results", although it seems circular, as it seems that "risk of bias" is defined in terms of the effect of parameters on results. Some of the parameters within the "results" category seem to refer to how the data was collected, that is, the methodology, such as "measurement precision" and "sampling time". Consider redefining these parameter categories for a gain in clarity.

lines 186-189: these lines are repeating information shown in Table 1. I suggest replacing those lines by a list of the most common to the least common exploited material in the 24 papers.

lines 201, 213: to which protocol do you refer? Please clarify.

lines 256-258: this information of this sentence seems to be too specific to one specific study, and maybe unnecessary here. I recommend eliminating this sentence.

Table 4: I believe this table is unnecessary. This is because all job types listed here were exposed to particle sizes differing in a very narrow range (between 2-8 microns). Except maybe for "Machine operator", which may classify as PM2.5, all other classify as PM10. Thus, there is probably no differences in the impact of dust grain size on health among four of the five jobs listed here. I thus recommend eliminating this table and listing the jobs in the text.

lines 347-348: please, add a reference here.

lines 359-362: Hotter does not necessarily means less humid. Please, be more specific about the characteristics of seasons in these two studies' sites. Also, hygroscopicity of dust aerosols will depend on several factors, including chemical composition. Please, expand this paragraph by citing papers that discuss hygroscopicity of dust aerosols, and connect to the nature of dust aerosols in these two studies ([5,27]).

lines 365-366: how is the connection between a synoptic-scale phenomenon such as anti-cyclones and local dust concentration? Please, expand this idea

section 4.6: a discussion of the results of the bias analysis is lacking in this section. Results are shown but are not discussed in the text. I recommend expanding this paragraph describing the results from this analysis.

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 1 comments

First of all, the authors would like to thank the Reviewer for taking the time to analyse and comment the manuscript, as it helps to improve the work quality. The Lines references is in relation to the manuscript with track changes options on. A slight difference appears in case this option is off.

Point 1: This review intends to identify conditions under which occupational exposure to mineral dust occurs, mostly in mining given that most available studies are restricted to this activity. Given that dust concentrations available in the literature of dust in the context of such activities were obtained under very different methodologies, the authors are not able to obtain quantitative results, or even robust qualitative results. In this sense, the conclusions obtained in this study do not represent an important contribution to the topic. However, the review itself was performed adequately, and the lack of useful results is fully due to the nature of available studies. In any case, the main conclusion from this manuscript is that a protocol is required for this kind of studies, a conclusion that was already reached by other authors (see reference [7] from this manuscript). One question is thus whether a review on this topic was warranted. The main reason for a positive answer on this question is that this review makes the necessity of a standard protocol even more evident. I recommend publishing this manuscript on Safety, provided some minor revisions are considered.

Response 1: The authors appreciate the comment and share the Reviewer's vision. Despite the main aim of the review, the main conclusion is the necessity of a standard protocol. Bearing that in mind, this manuscript core is relatable to a scoping review intention, much more than a systematic review, precisely for that matter. In that sense, a paragraph was included in Lines 460-462.

Point 2: lines 28-29: requires a reference, for example: Karanasiou, A., Moreno, N., Moreno, T., Viana, M., de Leeuw, F., & Querol, X. (2012). Health effects from Sahara dust episodes in Europe: literature review and research gaps. Environment international, 47, 107-114.

Response 2: The authors would like to thank the suggestion. The reference has been included in the manuscript.

Point 3: lines 45-48: I do not see the point of this paragraph. I believe it does not add any valuable information, and it breaks the connection between the preceding and the next paragraphs. I recommend eliminating it.

Response 3: The authors agree with this observation. For that reason, this paragraph was removed from lines 45-48. Nonetheless, the authors believe that it brings pertinent highlights to the subject; therefore, it was replaced further ahead, in Lines 93-96.

Point 4: lines 56-57: the source of this information needs to be stated.

Response 4: The authors are not quite sure what this point refers to… If it is related to the sentence "Recently, in 2020, it was reported that in the U.K., 12,000 lung disease deaths are linked to past exposures at work each year." The reference is from HSE in the footnote. However, the authors amended the sentence as it was rooked.

Point 5: line 66: Is the objective of this sentence to state that coal is the commodity whose mining leads to the greatest rise in lung disease cases? If so, this sentence should be re-written for greater clarity. I suggest: "..., leading the rise in new cases of lung disease, ...".

Response 5: The authors appreciate the comment and have corrected the sentence according to the suggestion.

Point 6: lines 108-112: it should be briefly mentioned why you chose those databases/journals.

Response 6: The authors appreciate the suggestion; an additional sentence was added to explain the reason for that selection, Lines 119-120. The authors hope this information is enough but are available to include any further explanation.

Point 7: lines 142-150: it is not clear what is meant by "the risk of bias within studies". It seems to refer to whether each defined parameter has an effect on results or not. Please, state what you mean by "risk of bias", as "bias" may be defined in very different ways. Also, at this point in the text, the reader does not know what results will be analyzed. Is it dust concentration? Please, be more specific here. Finally, one of the categories of the analyzed parameters is "results", although it seems circular, as it seems that "risk of bias" is defined in terms of the effect of parameters on results. Some of the parameters within the "results" category seem to refer to how the data was collected, that is, the methodology, such as "measurement precision" and "sampling time". Consider redefining these parameter categories for a gain in clarity.

Response 7: The authors acknowledge that the categories definition is not foreseen as adequate. Therefore, the Results category was removed, and the parameters were included in the Methodology. Scoping reviews go through a body of evidence to address a specific research question. In order to do that, certain parameters have to be defined beforehand. In this case, as the research is related to collecting evidence on the occupational exposure to dust in terms of setting and circumstances, all the parameters are related to the applied protocol. The risk of bias intends to assess the influence of such parameters in the obtained results. Additionaly, a new paragraph was added to the manuscript explaining what is referred by "risk of bias within studies" in Lines 156-157.

Point 8: lines 186-189: these lines are repeating information shown in Table 1. I suggest replacing those lines by a list of the most common to the least common exploited material in the 24 papers.

Response 8: The authors appreciate the suggestion, having proceed accordingly.

Point 9: lines 201, 213: to which protocol do you refer? Please clarify.

Response 9: The authors appreciate the comment, having clarified both mentions. That "protocol" refers to each papers' methodology.

Point 10: lines 256-258: this information of this sentence seems to be too specific to one specific study, and maybe unnecessary here. I recommend eliminating this sentence.

Response 10: The authors understand the point raised by the Reviewer. However, as this represents important information, despite being eliminated from the text, it was included as additional information in the Table  3.

Point 11: Table 4: I believe this table is unnecessary. This is because all job types listed here were exposed to particle sizes differing in a very narrow range (between 2-8 microns). Except maybe for "Machine operator", which may classify as PM2.5, all other classify as PM10. Thus, there is probably no differences in the impact of dust grain size on health among four of the five jobs listed here. I thus recommend eliminating this table and listing the jobs in the text.

Response 11: The authors appreciate the comment, having included the correction in the manuscript, Lines 307-310.

Point 12: lines 347-348: please, add a reference here.

Response 12: The authors would like to thank the comment, the reference was added.

Point 13: lines 359-362: Hotter does not necessarily means less humid. Please, be more specific about the characteristics of seasons in these two studies' sites. Also, hygroscopicity of dust aerosols will depend on several factors, including chemical composition. Please, expand this paragraph by citing papers that discuss hygroscopicity of dust aerosols, and connect to the nature of dust aerosols in these two studies ([5,27]).

Response 13: The authors appreciate the comment and agree with the made observations. As this manuscript reports to a scoping review, the body of evidence was collected for it was and information was mainly worked from what the actual authors reported. Unfortunately, the presented results (in addition to the applicable methodologies) do not provide enough information to discuss most of the obtained conclusions (by the respective authors).

Point 14: lines 365-366: how is the connection between a synoptic-scale phenomenon such as anti-cyclones and local dust concentration? Please, expand this idea

Response 14: The authors appreciate the comment; however do not possess any particular information that can help discuss that idea… As referred for Point 13, these were conclusions achieved by the respective authors, but the article report provides little or no information on that matter.

Point 15: section 4.6: a discussion of the results of the bias analysis is lacking in this section. Results are shown but are not discussed in the text. I recommend expanding this paragraph describing the results from this analysis.

Response 15: The authors appreciate the recommendation and have included a new paragraph in Lines 435-442 with the standard rationale.

Every other revision from the file peer-review-15987262.v1.pdf was considered and included in the text.

Reviewer 2 Report

This manuscript analyzes the literature about occupational exposure to mineral dust. The authors made a lot of work in collecting and analyzing relevant papers, but in my opinion there are few points to be clarified,

It is necessary to better explain the scope of the investigation in the abstract and the introduction. The authors state that “the most significant conclusion of this study is not related to its objective, but it derives from it” please make clearer the concept.

What do you mean for “protocol for scoping review”? In the text it is related to the reference [32]

Please explain the sentence at page 6 lines 190-192 “Regarding "studied variables", most were inferred from the experimental protocol, as each study's outcome was not solidly related to the variable itself.”

Author Response

First of all, the authors would like to thank the Reviewer for taking the time to analyse and comment the manuscript, as it helps to improve the work quality. 

This manuscript analyzes the literature about occupational exposure to mineral dust. The authors made a lot of work in collecting and analyzing relevant papers, but in my opinion there are few points to be clarified,

Point 1: It is necessary to better explain the scope of the investigation in the abstract and the introduction. The authors state that "the most significant conclusion of this study is not related to its objective, but it derives from it" please make clearer the concept.

Response 1: The authors would like to thank the Reviewer for the observation and refer that those issues were addressed in the new version of the manuscript, more specifically in Line 19. As for the scope of the investigation, as it falls under the classification of scoping review, the direct objective passes by gathering evidence on a particular topic. In this case, the settings for occupational exposure to mineral dust in mining and earthmoving works.

Point 2: What do you mean for "protocol for scoping review"? In the text it is related to the reference [32].

Response 2: Prior to the research that led to the writing and submission of this scoping review, the research team drew the research protocol, as preconised by the Preferred Reporting Items for Systematic Review and Meta-analysis Protocols (in the updated version of the manuscript it reports to reference [34]). The aforementioned protocol for scoping review (reference [33] of the updated version of the manuscript) was submitted to an international journal with peer-review, where a set of experts on the matter reviewed and approved the referred protocol that served as the methodological basis for carrying this research. That protocol [33] details even more specifically all of the stages that the review had to undergo, making this manuscript the report of such search.  

Point 3: Please explain the sentence at page 6 lines 190-192 "Regarding "studied variables", most were inferred from the experimental protocol, as each study's outcome was not solidly related to the variable itself."

Response 3: The aim of this scoping review was to find a body of evidence related to the occupational exposure to dust in terms of setting (particular circumstances), so this information can be used on an investigation project that is currently being held at the University of Porto. However, due to the nature of the included reports, no actual correlations were found. On the contrary, the research team had to infer the possible relations from the papers' methodologies.

Reviewer 3 Report

The airborne dust concentration can be affected by many factors, including those factors that the authors have analyzed. Particularly in the field, it seems impossible that a single factor will be solo contributor. Therefore, the authors may focus on analyzing the interaction among these factors. As an example, the relationship between distance and dust concentration will be significantly affected by wind condition. It would be more appropriate to analyze the parameters “distance” and “weather (or wind) together to determine their interactive effects on dust concentration.

line 32: reference from the WHO need to be included.

table 3: “Range (mg.m-3)” and “Range (μg.m-3)” can be possibly combined by unit conversion.

Why the dust concentration in some studies listed in table 2 (e.g., 5, 8, 42, 44, 49) haven’t been included in table 3 and related analysis?

Author Response

First of all, the authors would like to thank the Reviewer for taking the time to analyse and comment the manuscript, as it helps to improve the work quality. 

Point 1: The airborne dust concentration can be affected by many factors, including those factors that the authors have analysed. Particularly in the field, it seems impossible that a single factor will be solo contributor. Therefore, the authors may focus on analysing the interaction among these factors. As an example, the relationship between distance and dust concentration will be significantly affected by wind condition. It would be more appropriate to analyse the parameters “distance” and “weather (or wind) together to determine their interactive effects on dust concentration.

Response 1: The authors would like to thank the comments and are aware that it is very difficult to isolate the factors contributing to such exposure. However, the authors cannot follow the recommendation of analysing the combination of different parameters as the eligible papers do not provide enough information to make a comparison. The first step after determining the eligibility of each article was to start collecting the data (both for methodologies and results). Then, the research team tried to cross the information to see what type of discussion would arise. Unfortunately, due to the variability and lack of information (despite the achieved conclusions by the authors), not enough data was provided. Therefore, the need of implementing standardised methodological protocols.

Point 2: line 32: reference from the WHO need to be included.

Response 2: The authors appreciate that the Reviewer pointed out that flaw, having included the reference in need.

Point 3: table 3: “Range (mg.m-3)” and “Range (μg.m-3)” can be possibly combined by unit conversion.

Response 3: The authors agree with the comment; nonetheless, this scoping review intended to show the high variability of information. The authors are not sure the results can be combined, as they derive from different experimental protocols and do not want to mislead potential readers. Therefore, the authors tried to stick to the original sets of data as much as possible.

Point 4: Why the dust concentration in some studies listed in table 2 (e.g., 5, 8, 42, 44, 49) haven’t been included in table 3 and related analysis?

Response 4: The authors acknowledge the pertinence of Point 4. The authors chose not to include data that was not objectively available. For instance, some of the articles presented their data in graphical form, which not all the time is easily read. Others reported data in terms of inhalable, thoracic and alveolic fractions. Using that data would include uncontrolled biases in the scoping review and would be misleading.

Reviewer 4 Report

This is an interesting study and worth publishing. There are probably a select few individuals that will get more out of it than others. One thing that i believe is important in a revision--make it known somehow in the title and abstract that this study has its strongest application to the mining environment. Doing this will ensure that people who may be most interested in this have the opportunity to find it within their own literature reviews. It seems that conducing a study most applicable to mining was not the original intent, however all but one of the studies you included were mining contextualized and the majority of the insights you propose are directed at the mining industry.

Author Response

First of all, the authors would like to thank the Reviewer for taking the time to analyse and comment the manuscript, as it helps to improve the work quality. 

Point 1: This is an interesting study and worth publishing. There are probably a select few individuals that will get more out of it than others. One thing that i believe is important in a revision--make it known somehow in the title and abstract that this study has its strongest application to the mining environment. Doing this will ensure that people who may be most interested in this have the opportunity to find it within their own literature reviews. It seems that conducing a study most applicable to mining was not the original intent, however all but one of the studies you included were mining contextualized and the majority of the insights you propose are directed at the mining industry.

Response 1: The authors acknowledge that the intent of the study was not to be so strictly applied to the mining environment, but because of the results it turned out to be. In that sense, the recommendation was followed, and the title changed.

Round 2

Reviewer 1 Report

I appreciate the detailed responses made to each of my comments. I can now recommend publication of this manuscript in Safety in its present form. The following are some extra, very minor modifications I recommend incorporating into the final manuscript:

Lines 408-411: definition of categories needs to be modified to coincide with the new definition made in the methods section of this revised manuscript.

Table 6: please, separate the horizontal line that limit the "Methodology" and "Other" categories, for a gain in clarity.

Line 475: This sentence: "Other specific assumptions were described but not general usable data." is not clear. Do you mean to say that the descriptions of other specific assumptions cannot be used as data? In that case, I recommend re-phrasing to: "Other specific assumptions were described but not in a way that may be used as data". Please, check if this modification retains the intended meaning.

Author Response

The authors would like to thank the Reviewer for taking the time to reassess the manuscript. All of the recommendations were followed:

1) Lines 408-411 -  definition of categories were modified to fit the new definition made in the methods section and also according to Table 6

2) Table 6 heading was modified to improve clarity

3) Line 475 was rewritten according to the suggestion "Other specific assumptions were described but not in a way that may be used as data" as it retains the intended meaning

Reviewer 2 Report

In my opinion the paper could be accepted in the present form.

Author Response

The authors would like to thank the Reviewer for taking the time to reassess the manuscript and to provide positive feedback on the effort made.

Reviewer 3 Report

There is a great limitation not able to analyze the possible interaction among contributing exposure factors. Glad that the authors discuss some limitations in their paper.

Author Response

The authors would like to thank the Reviewer for taking the time to reassess the manuscript and acknowledge the huge limitation regarding the fact that the interaction between exposure factors was not possible to determine. Hopefully, future studies will provide that kind of data so a more thorough analysis can be brought to the table.

Reviewer 4 Report

No further comments. 

Author Response

The authors would like to thank the Reviewer for taking the time to reassess the manuscript.