PCLM-D-24-00088

The environmental impact of different types of diagnostic tests at different phases of the COVID epidemic: a life-cycle analysis

PLOS Climate

Dear Dr. Vernez,

Thank you for submitting your manuscript to PLOS Climate. After careful consideration, we feel that it has merit but does not fully meet PLOS Climate’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

The manuscript has been evaluated by three reviewers, and their comments are available below.

Reviewers 2 and 3 have raised a number of concerns that need attention. However, reviewer 1's comments do not appear to be specific to this manuscript, so please focus on the issues discussed by reviewers 2 and 3 when revising your manucript

Please submit your revised manuscript by Jul 27 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at climate@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pclm/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

We look forward to receiving your revised manuscript.

Kind regards,

Steve Zimmerman, PhD

PLOS Staff Editor

Journal Requirements:

1. Please provide separate figure files in .tif or .eps format.

For more information about figure files please see our guidelines:  LINK

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2. Please provide more detail in the Methods section on the interviews and site visits conducted, and include information on who was interviewed and how they were recruited for the study. If participants provided consent to participate, or permits were obtained to access the facilities, please outline these methods.

3. You indicated that ethical approval was not necessary for your study. We understand that the framework for ethical oversight requirements for studies of this type may differ depending on the setting and we would appreciate some further clarification regarding your research. Could you please provide further details on why your study is exempt from the need for approval and confirmation from your institutional review board or research ethics committee (e.g., in the form of a letter or email correspondence) that ethics review was not necessary for this study? Please include a copy of the correspondence as an ""Other"" file.

Additional Editor Comments (if provided):

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Does this manuscript meet PLOS Climate’s publication criteria ? Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe methodologically and ethically rigorous research with conclusions that are appropriately drawn based on the data presented.

Reviewer #1: Partly

Reviewer #2: Partly

Reviewer #3: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: N/A

Reviewer #3: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available (please refer to the Data Availability Statement at the start of the manuscript PDF file)?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception. The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS Climate does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This study is very interesting; however, it needs significant revision and modification in terms of structure.

Incorporate the following Comments and Suggestions, then resubmit

1. Write the novelty of your study with five reasons why this study is different from other studies.

2. Please write a historical perspective of your study in the literature review section. Critical analysis of the literature review is necessary.

3. Specify Theoretical Modeling of the Study.

4. Please test if there is any Nonlinearity in the Data ?

5. The results of some sections are presented mechanically. Cross Connection is necessary (Is your finding similar to or contradicts other studies? If so why ?)

6. Create a Policy Suggestion on the Basis of your Findings

7. Please write sources in each and every Figure and Table of the research paper.

8. This manuscript requires proper proofreading and grammar checking

Reviewer #2: I want to preface my comments by making it clear that I am reviewing this manuscript from the perspective of an LCA expert. I do not have clinical, epidemiological, or immunological expertise and therefore I will not comment on issues like how the COVID tests are done or how well they work.

I can see potential for this study as an incremental, albeit valuable, addition to the growing literature on healthcare LCAs. However, the manuscript needs major reworking to be suitable for publication. The LCA study is hard to follow because you never clearly define the functional unit (though you mention the term in passing a few times) and there is no system boundary flow diagram. Though you've provided relevant details (e.g., quantities of materials used, ecoinvent processes selected) in the supplementary material, you mention on line 191 that you developed a "proprietary Excel tool" to perform the LCA. It is not clear what exactly is proprietary, and why? Isn't it better to be transparent? And did you not use LCA software (e.g., SimaPro, OpenLCA) to perform the calculations?

Specific comments:

- It is misleading to use the terms "environmental impact" and "life cycle assessment" when considering only one type of environmental impact -- global warming potential.

- COVID was a pandemic, not just an epidemic.

- Line 66: It is not the healthcare sector alone. This number includes indirect emissions. Therefore, I suggest revising to "the healthcare sector was directly and indirectly responsible..."

- Line 68: Are all of these emissions actually direct emissions?

- Line 107: Why is there no mention of endpoints in the abstract?

- Line 203: Why did you not report midpoint indicators other than global warming potential? Also note that ISO 14044 (which is not cited, but should be) prohibits the use of weighting in LCA studies making comparative assertions. At the very least, the "pre-weighting" results should also be reported for transparency.

- Line 318: I like how you contextualize the magnitude of your LCA results in this paragraph. 0.1% is a very small fraction of total GHG emissions. It begs the question: Why do we care? Shouldn't we care much more about the other 99.9%?

- Line 342: Calling 0.1% "modest" is a stretch, in my opinion. But you call it "modest" and then "significant" -- which sounds contradictory to me...?

The manuscript, and supplementary material, also needs a thorough proofread and edit. There are numerous inconsistencies in terminology -- for example:

- You seem to use the term "life cycle analysis" (which is incorrect) interchangeably with "life cycle assessment" (which is correct). Please consistently use the correct term.

- On line 75, you refer to personal protective equipment and "medical consumables" (reagents, test kits, vaccines) as "single-use materials". To me, a manufactured article (e.g., a piece of personal protective equipment) is not a "material," and neither is a vaccine.

- You use inconsistent terminology for greenhouse gas emissions. In some places, you use "equ. CO2" and in others you use "CO2 eq" or "CO2 equ" or even just "CO2 emissions." In another place (line 232), you use "CO2-equivalent impact." Please be consistent; I suggest CO2 eq.

- Line 338: "Environmentally friendly" is unscientific language. Consider "low impact" instead.

- Looking at the supplementary material, sometimes you use a period for the decimal point and sometimes you use a comma. Again, be consistent (and check the journal style and follow it).

Reviewer #3: Thank you for this interesting study that is of interest to the community.

Although this study is well conducted and well explained, I think it may benefit of few changes that may change its conclusions :

1) The authors do not take into account the fact that the patient need to go to the place where the test is performed. A rough estimate of few kms lead to a non negligible effect.

2) The authors used the ReCiPe model and GWP 100 model, but other models are of interest. For example, the ReCiPe egalitarian model takes into account the effect on health (DALY) over 500 years, and more importantly without discount rate (that implies that our lives has more value than the one of our grand grand children, decreasing by about 50% every 20 years). In this context, a DALY is equal to 80 tCO2

3) The authors do not take into account the fact that providing a test also requires (on top of production and transport) the building of a factory, headquarters, etc. The sales, general and administration emission factor is estimated to about 0.05-0.1 kgCO2/euro (represents roughly 20-30% of the pharma industry expenses). If a test cost is estimated to 10 euros, it leads to a rough estimate of 0.5-1 kgCO2.

4) the authors do not take into account the fact that more people are required to perform PCR tests, and that these persons need to get to work, etc. Similarly, these tests requires a lab, and therefore constructing a lab, buying reagents, PCR machines, etc.

Altogether, I think the results proposed are very conservative and estimated impact may be largely underestimated.

Adding the proposed missing parts (I tried to focus on the probably most impactful ones, but there may be others I forgot) may be much more realistic and of interest to the community.

Best regards

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6. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

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Reviewer #1: Yes:  Dr. Pabitra Kumar Jena, School of Economics, Shri Mata Vaishno Devi University, Katra, Jammu & Kashmir

Reviewer #2: No

Reviewer #3: No

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While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

PCLM-D-24-00088R1

The Global Warming Potential of different types of diagnostic tests at different phases of the COVID pandemic: a climate-focused life-cycle assessment

PLOS Climate

Dear Dr. Vernez,

Thank you for submitting your manuscript to PLOS Climate. After careful consideration, we feel that it has merit but does not fully meet PLOS Climate’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Dec 06 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at climate@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pclm/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

We look forward to receiving your revised manuscript.

Kind regards,

Stephane Goutte

Academic Editor

PLOS Climate

Journal Requirements:

Additional Editor Comments (if provided):

Dear authors,

I received now reports on your paper and there are still corrections to do.

Best

Stéphane Goutte

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: (No Response)

Reviewer #3: All comments have been addressed

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2. Does this manuscript meet PLOS Climate’s publication criteria ? Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe methodologically and ethically rigorous research with conclusions that are appropriately drawn based on the data presented.

Reviewer #2: Yes

Reviewer #3: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: N/A

Reviewer #3: Yes

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4. Have the authors made all data underlying the findings in their manuscript fully available (please refer to the Data Availability Statement at the start of the manuscript PDF file)?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception. The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

Reviewer #3: No

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS Climate does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

Reviewer #3: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: Thank you for diligently addressing my comments and those of the other reviewer.

I still have a few minor things to comment on:

- line 348: Is this total GWP of testing also for Switzerland? Please clarify which healthcare system this refers to.

- line 371: The terminology of "Scope 1" (or Scope 2 and Scope 3) emissions comes from the GHG Protocol Corporate Accounting and Reporting Standard. It applies to *corporate* GHG emissions accounting. Neither the GHG Protocol Product Life Cycle Accounting and Reporting Standard, nor the ISO standards for LCA, use this terminology. The reason is because the GHG emissions "scopes" are defined based on *organizational* boundaries (i.e., by operational control, financial control, or equity share). This is distinct from defining *product* system boundaries in LCA. Accordingly, please remove all uses of the "scopes" terminology, unless it is applied in relation to corporate GHG accounting as intended.

- line 376: I am confused by this: "...only 1,000 procedures of this type could be performed to be equivalent to the whole healthcare system." My reading of this is that 1,000 covid tests would be equivalent to the whole healthcare system, in terms of carbon footprint. That does not seem plausible. Earlier (line 348), you write: "In 2021, the total GWP of testing was 3,300 t CO2 eq., which represents 0.1% of the impact of the healthcare system." I would assume that the TOTAL GWP of testing is the GWP of ALL tests done in 2021 -- not just one test. 3,300 t CO2 eq. for *one test* does not seem plausible either. Please clarify what you mean by the TOTAL GWP of testing.

Reviewer #3: The authors responded to all comments by choosing to clearly define the boundaries of their analysis, and not taking into account other GHG emisions that may arise from the use COVID tests. They therefore focused on (a subpart) of scope 1 emissions.

The results is therefore probably relatively correct, but "only" a building block that requires to be integrated in a larger study that would try to take into account other sources of emissions (scope 2 and 3), that are expected to represent a large marjority of emissions.

in my opinion this needs to be clearly stated, even in the title, abstract, etc

Exemple : The direct emissions (scope I) related Global Warming Potential of different types of diagnostic tests at different phases of the COVID pandemic: a climate-focused life-cycle assessment

The reasons given use the Hierarchical ReCiPe scenario and not the egalitarian are not convincing :

"Besides, measuring DALYs over a longer timeframe (e.g. the egalitarian 500-year perspective) seems inappropriate, given the uncertainties surrounding the long term health of the population"

1) both may be done

2) Uncertainty was assessed with other models (tang et al, for exemple) and estimated to about +/-50%, which is not so uncertain

3) long term effect are expected as CO2 will not disapear after 2100

Regarding Sales general and administration, alhough the estimation is uncertain, it doesn't cost much to integrate it in the analysis, or at least in the discussion. Monetary emissions factors were recently proposed for the pharma industry (although not exactly similar) by Piffoux et al (journal of cleaner production 2024, or other sources). A rough estimation may be of interest to the reader

it is similar for the impact of building new labs and workers transport, a rough quantitative estimate in the discussion is of interest

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

Do you want your identity to be public for this peer review? If you choose “no”, your identity will remain anonymous but your review may still be made public.

For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #2: No

Reviewer #3: No

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[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

The direct emissions related to Global Warming Potential of different types of diagnostic tests at different phases of the COVID pandemic: a climate-focused life-cycle assessment A life-cycle assessment of COVID diagnostic tests (short title)

PCLM-D-24-00088R2

Dear Pr. Vernez,

We are pleased to inform you that your manuscript 'The direct emissions related to Global Warming Potential of different types of diagnostic tests at different phases of the COVID pandemic: a climate-focused life-cycle assessment A life-cycle assessment of COVID diagnostic tests (short title)' has been provisionally accepted for publication in PLOS Climate.

Before your manuscript can be formally accepted you will need to complete some formatting changes, which you will receive in a follow-up email from a member of our team. 

Please note that your manuscript will not be scheduled for publication until you have made the required changes, so a swift response is appreciated.

IMPORTANT: The editorial review process is now complete. PLOS will only permit corrections to spelling, formatting or significant scientific errors from this point onwards. Requests for major changes, or any which affect the scientific understanding of your work, will cause delays to the publication date of your manuscript.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they'll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact climate@plos.org.

Thank you again for supporting Open Access publishing; we are looking forward to publishing your work in PLOS Climate.

Best regards,

Stephane Goutte

Academic Editor

PLOS Climate

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Additional Editor Comments (if provided):

Reviewer Comments (if any, and for reference):

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #3: All comments have been addressed

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2. Does this manuscript meet PLOS Climate’s publication criteria ? Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe methodologically and ethically rigorous research with conclusions that are appropriately drawn based on the data presented.

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available (please refer to the Data Availability Statement at the start of the manuscript PDF file)?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception. The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS Climate does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #3: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #3: thanks for the work

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

Do you want your identity to be public for this peer review? If you choose “no”, your identity will remain anonymous but your review may still be made public.

For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #3: No

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