Chemical Footprint as an Indicator of Health Impacts: The Case of Dioxins and Furans in Brazil

Round 1

Reviewer 1 Report

This manuscript talks about the use of the model USEtox to estimate the impact of the emission of dioxins and furans in Brazil and its impact on the population. This is quantified from data of the National Implementation Plan of the Stockholm Convention applied in this country. The authors use some parameters like Chemical Footprints (one of the proposed approaches used in the bibliography) and Characterization Factors (midpoint or endpoint) specific to the studied compound related to toxicity, which can be translated into monetary valuation using, in this study, Valuation Factors based on the US Dollar. The estimation drives to obtain a value (DALY) that represents the theoretical loss of years of the life of the Brazilian population and the possibility of expressing them as a loss of money as the social cost. I think the manuscript is appropriate and I consider it well-structured. The text is clear and well-documented.

In my opinion, the value of this model can be very satisfactory, although maybe in the short future, some other factors can be taken into account. It has demonstrated its utility indicating the most polluted areas of the country, the activities that mainly contribute to the total emission or the possibility of translating into money.

Anyway, I have some comments or questions for the authors in the coming sections.

General considerations

This is a comment to the authors or maybe to the editor. Some parts of the document show bigger letters in different parts. I give a few examples: L. 4. Superscript for the first author; L. 120. USEtox.org; L. 225. Equation number 1.

Back matter

The authors should add information about Author Contribution, Funding, Institutional Review Board Statement, Informed Consent Statement, Data Availability Statement and Conflict of Interest.

Abstract

·         The abstract contains 294 words according to my count. They are 94 more words than specified in the guide for authors.

·         L. 23.  As the authors have used an acronym for Chemical Footprint, they maybe could use another one for Persistent organic Pollutants. I leave it to their consideration because they have added it in line 146.

·         In line 28, I consider it better to use lowercase for 'dioxins'.

Results

·         Dioxins and furans are lipophilic compounds and they accumulate in fatty tissue in living organisms. That is why they can bioconcentrate and biomagnify. For them and many other families of similar compounds, ingestion of food is the main pathway of entry. Do you consider that this should be taken into account in the next studies or they would be redundant? What about imported food?

·         Due to the cross-border effect, do you have data to think of the influence of surrounding countries? What would be the effect of wind from the Sahara desert that arrives in your country with different POPs adsorbed? Could this have a significant effect?

·         Thinking of polychlorinated biphenyls (PCBs), another family narrowly to dioxins and furans, some congeners have associated different Toxic Equivalent related to 2,3,4,7, TCDD. They are named Dioxin-like PCBs. Are you planning to add them to the next studies? I think they should be very interesting.

Tables and figures

·         In different tables, bold letters and some lines are bold in the first entry of data. For instance, in table 1, midpoint versus endpoint. Also, for instance, in table 2, the heading is messed up. Please check all of them.

·         Figure 4. Are units in X-axis right? The results for the social cost are expressed in the text as USD 30 million, for instance. In this case, and according to the vertical legend this would mean thousands of millions instead. Please, check it.  

Citations and references

• Please, check all references and try to fit them into the model suggested by the journal in the Instructions for Authors: title of articles not in italics, journal names in abbreviated form and italics, publication year in bold type, volume in italics and pages range when possible.
• Also, please, remove the number ‘22’ appearing in line 634 and ‘37’ at the end of the references.

Author Response

Comments and Suggestions for Authors

Reviewer 1: This manuscript talks about the use of the model USEtox to estimate the impact of the emission of dioxins and furans in Brazil and its impact on the population. This is quantified from data of the National Implementation Plan of the Stockholm Convention applied in this country. The authors use some parameters like Chemical Footprints (one of the proposed approaches used in the bibliography) and Characterization Factors (midpoint or endpoint) specific to the studied compound related to toxicity, which can be translated into monetary valuation using, in this study, Valuation Factors based on the US Dollar. The estimation drives to obtain a value (DALY) that represents the theoretical loss of years of the life of the Brazilian population and the possibility of expressing them as a loss of money as the social cost. I think the manuscript is appropriate and I consider it well-structured. The text is clear and well-documented.

In my opinion, the value of this model can be very satisfactory, although maybe in the short future, some other factors can be taken into account. It has demonstrated its utility indicating the most polluted areas of the country, the activities that mainly contribute to the total emission or the possibility of translating into money.

 Anyway, I have some comments or questions for the authors in the coming sections.

Authors: We are thankful for your comments and suggestions, which surely will improve the quality of the manuscript.

Reviewer 1

General considerations

This is a comment to the authors or maybe to the editor. Some parts of the document show bigger letters in different parts. I give a few examples: L. 4. Superscript for the first author; L. 120. USEtox.org; L. 225. Equation number 1.

Authors: Textual mistakes were now corrected. 

Back matter

 The authors should add information about Author Contribution, Funding, Institutional Review Board Statement, Informed Consent Statement, Data Availability Statement and Conflict of Interest.

Authors: Done.

Abstract

• The abstract contains 294 words according to my count. They are 94 more words than specified in the guide for authors.
• L. 23.  As the authors have used an acronym for Chemical Footprint, they maybe could use another one for Persistent organic Pollutants. I leave it to their consideration because they have added it in line 146.
• In line 28, I consider it better to use lowercase for 'dioxins'.

Authors: Abstract was re-written for objectives; it has now 213 words. An acronym for Persistent Organic Pollutants (POPs) was included. The word ‘dioxins’ at L.23 was now corrected.

Results

• Dioxins and furans are lipophilic compounds and they accumulate in fatty tissue in living organisms. That is why they can bioconcentrate and biomagnify. For them and many other families of similar compounds, ingestion of food is the main pathway of entry. Do you consider that this should be taken into account in the next studies or they would be redundant? What about imported food?

Authors: The fraction of dioxins and furans absorbed by the organism is somehow considered by the USEtox model. Running the model, the ingestion fraction takes into account the ingestion of water and food to calculation of the effects on human health. This aspect is now highlighted in the revised manuscript.

Regarding the imported food, accounting for the amount of water and food coming from other locations could bring accuracy for results, similar to “footprints” concept. The hypothetical inclusion of these data would involve compiling a large amount of information from specific geographic regions, which would make the model more accurate on a local scale, but inadequate to be replicated generically on a global scale. We have added this suggestion to section 3.5 as limitations of the study.   

• Due to the cross-border effect, do you have data to think of the influence of surrounding countries? What would be the effect of wind from the Sahara desert that arrives in your country with different POPs adsorbed? Could this have a significant effect?

Authors: We are glad to have such an important question about the subject. Data on the influence of external pollutants on the Brazilian territory were not accessed and not considered. The amount of dioxins and furans migrating to or from other locations could significantly impact the results. We have added comments on this subject in the 3.5 section of the revised manuscript.

• Thinking of polychlorinated biphenyls (PCBs), another family narrowly to dioxins and furans, some congeners have associated different Toxic Equivalent related to 2,3,4,7, TCDD. They are named Dioxin-like PCBs. Are you planning to add them to the next studies? I think they should be very interesting.

Authors: The inclusion of these pollutants classes was in our initial idea for the manuscript, but unfortunately there is not available a Brazilian national inventory containing data on them. As these are intentionally used substances, information on a national scale basis about that substance (environmental liability) is related with the amount of PCBs existing in equipment (in use and out of use) and does not include PCBs released on the environmental compartments of air, soil and water. This is a limitation of the study, and it was included in item 3.5 of the revised manuscript. Thanks for your observation.

Tables and figures

• In different tables, bold letters and some lines are bold in the first entry of data. For instance, in table 1, midpoint versus endpoint. Also, for instance, in table 2, the heading is messed up. Please check all of them.

Authors: Done.

• Figure 4. Are units in X-axis right? The results for the social cost are expressed in the text as USD 30 million, for instance. In this case, and according to the vertical legend this would mean thousands of millions instead. Please, check it. 

Authors: Figure 4 was revised accordingly. Thanks.

Citations and references

Please, check all references and try to fit them into the model suggested by the journal in the Instructions for Authors: title of articles not in italics, journal names in abbreviated form and italics, publication year in bold type, volume in italics and pages range when possible.

Also, please, remove the number ‘22’ appearing in line 634 and ‘37’ at the end of the references.

Authors: Done. Thanks.

Reviewer 2 Report

The manuscript entitled " Chemical footprint as an indicator of health impacts: the case of dioxins and furans in Brazil " which has been submitted to Sustainability for possible publication fits the scope of the journal. The topic is very interesting since the proposed model, if applied, could help: a) researchers to characterize human and ecotoxicological impacts of chemical emissions in life cycle assessment; b) policymakers to allow visualizing specific and focused policies toward the reduction of toxic chemical emissions for the purpose of provide environmental and human health protection. In particular, this study aims to propose a new way to calculate Chemical Footprint (ChF) for dioxins and furans and applied it to Brazil as a case study. The manuscript is clearly written, well-organised also if, in some parts of paragraphs, it appears too verbose. The study is well conducted and is understandable even for those unfamiliar with the topic. The number of references seems to be adequate to what is actually necessary.

Limitations of the study have been taken into account.

However, I have just a few minor comments/suggestions in order to improve the quality of the current paper. Please, read below and correct as required:

1.       Lines 634 and 676: please, cancel

2.       In my opinion a short introduction about dioxins and furans (PCDDs and PCDFs) can be desirable.

3.       Why didn’t you also consider dioxin-like polychlorinated biphenyls (DL-PCBs)? PCDDs/PCDFs and DL-PCBs are a group of environmental pollutants with similar structures and toxic effects.

4.       I have not understood whether the application of this new method (to calculate ChF) allows to consider several chemical substances simultaneously that are in the same site (analysis of chemical mixture) in order to evaluate the burden of disease in a population.

Author Response

Comments and Suggestions for Authors

Reviewer 2: The manuscript entitled " Chemical footprint as an indicator of health impacts: the case of dioxins and furans in Brazil " which has been submitted to Sustainability for possible publication fits the scope of the journal. The topic is very interesting since the proposed model, if applied, could help: a) researchers to characterize human and ecotoxicological impacts of chemical emissions in life cycle assessment; b) policymakers to allow visualizing specific and focused policies toward the reduction of toxic chemical emissions for the purpose of provide environmental and human health protection. In particular, this study aims to propose a new way to calculate Chemical Footprint (ChF) for dioxins and furans and applied it to Brazil as a case study. The manuscript is clearly written, well-organised also if, in some parts of paragraphs, it appears too verbose. The study is well conducted and is understandable even for those unfamiliar with the topic. The number of references seems to be adequate to what is actually necessary.

Limitations of the study have been taken into account.

Authors: We are thankful for your comments and suggestions, which will surely improve the manuscript's quality.

Reviewer 2:

However, I have just a few minor comments/suggestions to improve the quality of the current paper. Please, read below and correct as required:

1. Lines 634 and 676: please, cancel

Authors: We believe the mistake occurred during the manuscript formatting procedure performed by the MDPI office. Note that all references are doubled numbered. That formatting mistake will probably be corrected in the final proof document.

2. In my opinion a short introduction about dioxins and furans (PCDDs and PCDFs) can be desirable.

Authors: Suggestion accepted. We have added the following text to the manuscript:

“Dioxins and furans are chemicals produced unintentionally, mainly due to incomplete combustion process, but also from other manufacture processes such as pesticides, chlorinated substances, among others. Dioxins (Polychlorinated dibenzo-p-dioxins -PCDD) and furans (Polychlorinated dibenzofurans - PCDF) are listed under annex C in Stockholm Convention and are part of the POPs which have a long residence time in the environment, a low rate of degradation and a high potential to cause harmful impacts to humans and the environment.”

3. Why didn’t you also consider dioxin-like polychlorinated biphenyls (DL-PCBs)? PCDDs/PCDFs and DL-PCBs are a group of environmental pollutants with similar structures and toxic effects.

Authors: The inclusion of these pollutants classes was in our initial idea for the manuscript, but unfortunately there is not available a Brazilian national inventory containing data on them. As these are intentionally used substances, information on a national scale basis about that substance (environmental liability) are related to the amount of PCBs existing in equipment (in use and out of use) and does not include PCBs released on the environmental compartments of air, soil and water. This is a limitation of the study, and it was included in item 3.5 of the revised manuscript. Thanks for your observation

4. I have not understood whether the application of this new method (to calculate ChF) allows to consider several chemical substances simultaneously that are in the same site (analysis of chemical mixture) in order to evaluate the burden of disease in a population.

Authors: The application of the Chemical Footprint makes it possible to measure and compare the impact on human health caused by several/different chemical substances simultaneously by converting all of them on the same comparison basis. However, as usual for any existing model in the literature, chemical substances are considered individually instead of blending them to obtain a new/different substance with a different impact. This is not an exclusive limitation of the proposed model, since it exists in most - if not all of them - available models that quantify the toxicological impacts of chemical substances on human health. None available method is capable of covering this aspect precisely. See for instance the book of Hauschild & Huijbregts (2015)* in this regard.

The proposed approach in this study goes beyond the simple toxicity assessment because it includes the USETOX model to assess the exchange or mobility of each substance among the environmental compartments (air, soil, and water), and its potential effects on human health. This can be considered an advance on the existing similar models for higher accuracy.

All these comments are now presented in the revised manuscript. Thanks for your observation.

* Michael Z. Hauschild, Mark A.J. Huijbregts (editors), 2015. LCA Compendium – The Complete World of Life Cycle Assessment. Springer Dordrecht, https://doi.org/10.1007/978-94-017-9744-3.