Cancer Risk Associated with Residential Proximity to Municipal Waste Incinerators: A Review of Epidemiological and Exposure Assessment Studies

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript presents a comprehensive review of epidemiological and exposure assessment studies examining the relationship between municipal solid waste incinerators (MSWIs) and cancer risks. The study synthesizes a substantial body of global research, offering valuable insights into the complexities of this issue. While the manuscript demonstrates a thorough understanding of the topic and provides a broad geographical coverage of studies from Europe, the US, and Asia, several critical areas require substantial revision to strengthen its scientific rigor, methodological clarity, and policy relevance. After major revisions addressing the points below, the manuscript could be considered for publication：

(1) While the review notes inconsistencies across studies, the methodological bases for these discrepancies (e.g., exposure assessment methods, confounding variables, study designs) could be further explored.

(2) Consideration might be given to expanding the discussion of how socioeconomic disparities, racial/ethnic minorities, and low-income communities experience disproportionate impacts from MSWI exposures. Potential policy responses addressing these inequities (e.g., participatory siting processes, enhanced monitoring in vulnerable areas) could be incorporated.

(3) The challenges of conveying complex scientific uncertainties to public and policy audiences might benefit from additional analysis. Frameworks balancing evidentiary standards with precautionary approaches could be proposed, particularly in regions with limited regulatory infrastructure.

(4) Discussions of historical versus contemporary MSWI technologies and their associated risks might be structured using subheadings. Key studies could be summarized in tabular format to enhance readability (e.g., study location, design, exposure metric, main outcome).

Author Response

Please see attached file.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The review titled "Cancer Risk Associated with Residential Proximity to Two Municipal Work Incinerators: A Review of Epidemiological and Exposure Assessment Studies" provides a comprehensive synthesis of existing epidemiological and exposure assessment studies related to the potential cancer risks associated with living near municipal waste incinerators. It effectively consolidates significant findings from various research efforts, highlighting key trends and gaps in current knowledge.

 

Here are my comments:

 

1. The methodology section should be enhanced by detailing the criteria used for article selection, especially given that the initial searches likely yielded a broad array of results. Clearly outline how studies were screened and selected to ensure transparency and comprehensiveness.

 

2. The statement "However, more recent studies have shown no significant association or even potential risk reductions" (lines 221-223) lacks necessary references to substantiate its claims. As this is a key conclusion, it's essential to include specific citations that support advancements in incinerator technology and stricter environmental regulations leading to these findings. Additionally, briefly evaluating the methodologies of these studies could help determine their reliability. Discussing any limitations or biases within these studies would provide a clearer context for understanding why some report no significant associations or risk reductions compared to earlier research. This approach enhances credibility and offers readers deeper insights into the evolving assessment of cancer risks associated with incinerators.

 

3. For consistency and clarity in scientific writing, use a uniform notation for expressing numerical values throughout the document. Currently, two different formats are being used: `e` notation (e.g., 1.07E-07) and scientific notation with multiplication signs and powers of ten (e.g., 2 × 10^-4). It is recommended to choose the journal's recommended format and apply it consistently across all similar instances.

 

4. The absence of documented studies or reported data on incineration technologies in Latin America and Africa suggests a significant gap in the literature. This lack could be indicative of several underlying issues, such as the prevalence of clandestine operations rather than formalized waste management practices. It would be beneficial to address this by encouraging future research in these regions to fill this knowledge gap and better understand local risks associated with incineration.

Author Response

Please see attached file.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This is a well-structured and comprehensive narrative review that synthesizes the epidemiological and exposure assessment literature on cancer risks related to residential proximity to Municipal Solid Waste Incinerators (MSWIs). The study offers a balanced synthesis of multi-national data, particularly from Europe, North America, and Asia. The conclusions are generally cautious and evidence-based, acknowledging limitations and emphasizing the need for continuous monitoring despite technological advances in emission control. Overall, I commend the author for the manuscript. However, some major revisions are necessary to enhance the overall quality, precision, and utility of the review for scientific, policy, and community audiences.

- My main concern—and the area that I believe requires the most attention—is the methodological description of the review. The search strategy is only briefly described. While some flexibility is acceptable in narrative reviews, certain elements need to be better defined, such as the Study Selection and Eligibility Criteria (e.g., inclusion and exclusion criteria, whether only studies published in English were considered), as well as whether any form of quality assessment was performed.

- At no point is it clearly reported how many studies were initially retrieved and how this number was narrowed down to the final set of included articles. This information is important for transparency. To avoid altering the structure of subsequent sections, I suggest including these review "results" directly in the methodology section.

- The summary sections describing the reviewed studies often present long paragraphs in a format resembling abstracts. I recommend breaking up these lengthy texts into smaller paragraphs to improve readability and maintain reader engagement.

- I suggest including a map showing the geographic distribution of the studies reviewed (number of studies). A visual representation would greatly aid the interpretation and geographical contextualization of the findings.

- Tables 1 and 2 must be introduced in the text before they appear. Currently, the tables are only referenced in the discussion (Section 6), while the tables themselves appear earlier in Sections 3 and 5. Add brief introductory and summary sentences around the table placements to better integrate them into the narrative.

- Regarding Table 2, I recommend separating the studies from North America and presenting them in a dedicated table under Section 4, instead of combining them with the data from Section 5.

- Since there are no studies from Central or South America included in the review, I suggest adjusting the label in Section 4 from "American studies" to "North American studies," as the technological and developmental context in North America differs significantly from that of other regions in the Americas.

- It is important to include a discussion on the absence of studies from other major global regions.

- Finally, consider briefly addressing potential policy alternatives to MSWIs (e.g., zero-waste strategies, mechanical-biological treatment) in the discussion to contextualize MSWIs within a broader waste management framework.

Author Response

Please see attached file.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

I am pleased to confirm that all my previous concerns have been adequately addressed. The revisions have significantly improved the manuscript, and I now consider it suitable for publication.