Association between Aqueous Atrazine and Pediatric Cancer in Nebraska

Round 1

Reviewer 1 Report

This well written manuscript provides informative data in support of hypothesis associating atrazine contamination of selected groundwater and surface water sources with regional incidences of pediatric cancer. The authors did well by describing the strengths and limitations of their research, including the need to have a comparison control site. The following are a few revision recommendations for the authors' consideration:

Methods section (line 74): Explain the reasoning for only using data from irrigation wells instead of household use wells.

Line 102: Define/explain "records were tied".

Line 193: It seems that "water atrazine" should be groundwater atrazine.

 

 

Author Response

Methods section (line 74): Explain the reasoning for only using data from irrigation wells instead of household use wells.   

            Thank you for the question. As the private household wells are not regulated by the Nebraska state/federal level, the water quality data is not publicly available. We are unable to access private well water samples. Data used in this study were the most accurate and reliable data that were publicly available. As the atrazine measurements included in this study were analyzed by professional laboratories.

Line 102: Define/explain "records were tied".

            Thank you for the comment. For improved clarity, the sentence was changed to (see line:147) “Most of the study subjects were automatically matched by complete address (99.1%; n=2,538), and negligible records (0.9%; n=21) were tied (matched with multiple locations).”

Line 193: It seems that "water atrazine" should be groundwater atrazine.

            Thank you. This wording was changed throughout the manuscript.

Reviewer 2 Report

Dear authors,

your paper "Association between aqueous atrazine and pediatric cancer in Nebraska" is interesting and worth publishing. Since the water quality and cancer incidences are linked, choosing Water is understandable. Maybe a cancer research journal will attract a greater audience to your paper...

Specific comments to your MS follow below:

1. The abstract contains 281 words and is a little bit over the requirements of the template (maximum 200).
2. Please explain that "agrichemicals" is a general term for substances used in agriculture before using it in the MS (abstract, lines 261, 266, 277, etc.)
3. Please define the abbreviation and then put the abbreviation letters in parentheses (e.g. lines 37, 44, 52).
4. Line 59: please insert "potential" into the objective of the study - it should read "potential association".
5. Please describe the methods used for the determination of atrazine in the water samples. As these data are obtained from 3 databases, the method(s) used should be stated for possible data comparisons.
6. It is mandatory to include the LOQ of the method used, especially if there are different methods employed.
7. Line 162: please include data and comparisons values for the stated "higher than the national average".
8. Lines 170-172: please add values for "high surface/ground atrazine concentrations", "earlier age" and "lower atrazine concentrations".
9. Line 186: please explain in more detail "statistically significant" - add p=?, n=?, the method used (ANOVA presumably). 
10. Lines 196-201: this paragraph is more suitable for the Conclusions.
11. Figure 2: please add "Water" to "Ground" and "Surface" and "concentration in the first sentence in line 207.
12. Table 1: please check the first value in column 6. It can not stay as "0.000".
13. Lines 226-228: please add an explanation "how much lower"?
14. Lines 233-235 and 301: please describe "how significant" the association is (p=?, n=?).
15. Line 263: please ad references 32 and 33 to the reference list. They are missing in the current version of the MS.
16.  Line 271: please describe that "all the subjects diagnosed" are children <19 years old.
17. The template of Water states that "Include the digital object identifier (DOI) for all references where available", which is not done in your MS. Please check reference 16 for completeness and all for letter/font size.

Author Response

 

1. The abstract contains 281 words and is a little bit over the requirements of the template (maximum 200).

 

Thank you for the comment. We revised and refined the abstract to 179 words.

 

1. Please explain that "agrichemicals" is a general term for substances used in agriculture before using it in the MS (abstract, lines 261, 266, 277, etc.)

 

Thank you for the suggestion. We updated the manuscript with the explanation for agrichemicals.

Line 13: “Agrichemicals, chemicals used to maximize crop and animal production, can lead to water quality concerns when these chemicals run off into surface and groundwater after precipitation events.”

 

1. Please define the abbreviation and then put the abbreviation letters in parentheses (e.g. lines 37, 44, 52).

 

We updated the abbreviations.

 

1. Line 59: please insert "potential" into the objective of the study - it should read "potential association".

 

Thank you the objective statement was updated (see line: 86).

 

1. Please describe the methods used for the determination of atrazine in the water samples. As these data are obtained from 3 databases, the method(s) used should be stated for possible data comparisons.

 

Thank you for the question. We updated the methods section with the following information:

See lines: 110-116: “The water samples reported by the clearinghouse were analyzed using Enzyme-Linked Immunosorbent Assay (ELISA) method with a level of quantification (LOQ) of 0.05 μg/L [22]. The USGS samples were analyzed using Gas Chromatography with Mass spectrometry (GC/MS) with Single Ion Monitoring with a LOQ of 0.01 μg/L and Liquid chromatography with tandem mass spectrometry (LC/MS/MS) with a LOQ of 0.01 μg/L [19]. The water samples from the STORET database were based on US EPA method 507 (Gas Chromatography with a Nitrogen-Phosphorus detector) with a LOQ of 0.01 μg/L [23].”

 

1. It is mandatory to include the LOQ of the method used, especially if there are different methods employed.

 

We included the information on level of quantification along with the instrumentation in the methods section (see lines: 110-116).

 

1. Line 162: please include data and comparisons values for the stated "higher than the national average".

 

Thank you for the suggestion. We updated line 162 with “The annual mean age-adjusted pediatric cancer incidence in Nebraska was higher than the national average during 2011 (18.82, 18.04), 2012 (19.79, 17.80), 2015 (19.30, 19.03), and 2016 (20.79, 18.60).”

 

1. Lines 170-172: please add values for "high surface/ground atrazine concentrations", "earlier age" and "lower atrazine concentrations".

 

Updated with the sentence (see line 225) with atrazine concentrations and the median age of children diagnosed with cancer.

 

1. Line 186: please explain in more detail "statistically significant" - add p=?, n=?, the method used (ANOVA presumably).

 

Thank you for this comment to improve clarity. As the objective of this study is to compare low/medium/high atrazine with negligible atrazine watersheds (output from figure. 2). We used the Generalized Linear Model framework instead of using ANOVA which compares the group differences. From the GLM output, we obtained confidence interval to highlight the statistical significance, instead of p-values that are commonly presented with ANOVA. If the 95% CI include 1, then the incidence rate ratio is non-significant. We could notice non-significant results for low-goundwater in adjusted_1 result, and low-surface water unadjusted & adjusted_2 results. Additionally, updated the figure description on line 286.

 

1. Lines 196-201: this paragraph is more suitable for the Conclusions.

 

Thank you. We moved to suggested paragraph to the conclusion section (see lines 387-392).

 

1. Figure 2: please add "Water" to "Ground" and "Surface" and "concentration in the first sentence in line 207.

 

Updated figure labels to (see line: 279) “ground_water” and “surface_water”. Updated the figure label to “Association between atrazine concentration and pediatric cancer”.

 

1. Table 1: please check the first value in column 6. It can not stay as "0.000".

 

Replaced the value “0.000” with “0” for the Mud watershed (see line: 288).

 

1. Lines 226-228: please add an explanation "how much lower"?

 

Thank you for the question. We added the percentage difference between the IRRs obtained from adjusted_1 model to unadjusted/adjusted_2 model (see lines: 301-303).

 

1. Lines 233-235 and 301: please describe "how significant" the association is (p=?, n=?).

 

As the GLM model output provides effect estimates and 95% confidence interval, we removed the term significance and replaced with direction of association (positive), throughout the manuscript.

 

1. Line 263: please ad references 32 and 33 to the reference list. They are missing in the current version of the MS.

 

Thank you. We updated the bibliography with references 32 & 33 (see lines: 619-623).

 

1.  Line 271: please describe that "all the subjects diagnosed" are children <19 years old.

 

Thank you. We modified line 271 to “The current study is based on a longer period (30 years) that included all children less-than twenty years old, diagnosed with pediatric cancer in Nebraska and the associations were based on water quality measurements which would be comparatively accurate than attributing to agricultural land use pattern.”

 

1. The template of Water states that "Include the digital object identifier (DOI) for all references where available", which is not done in your MS. Please check reference 16 for completeness and all for letter/font size.

 

Thank you. We updated the bibliography with DOIs for all the references cited in the manuscript and corrected reference #16 (see lines: 487-489).

Reviewer 3 Report

Water

Manuscript Number: water-1396802

Title: Association between aqueous atrazine and pediatric cancer in 2 Nebraska

Reviewer' comments:

Overall statement of the article

The paper, water-1396802 “Association between aqueous atrazine and pediatric cancer in 2 Nebraska ” submitted to Water Journal for publication, aims to to evaluate the association be-59 tween aqueous atrazine and pediatric cancer.

The paper contains 5 keywords:  Watersheds, atrazine, pediatric cancer, herbicides, water quality.

This work is divided into 4 distinct parts: (i) Abstract, (ii) Introduction, (iii) Material and Methods, (iv) Results  and (v) Conclusion.

The paper has 1 table and 2 figures. There are 31 references, which are from 1997 to 2020. The majority of the references are internationally evaluated and published in peer-reviewed journals.

According to the authors,statistically significant associations exist between atrazine surface water concentrations, atrazine groundwater concentrations, and the incidence of pediatric cancer in Nebraska.

 

Overall strengths of the article

The title is clear. The authors have clearly state the objectives of the article.

The article reflects a current state of knowledge with a sufficiently critical and internationally evaluated literature. However, the structure of the article will need to be revised.

The methodology of the study needs to be strengthened.

The paper needs to be revised in order to make it more impactful.

The reviewer asks the authors:

1. to present the physical and chemical properties of atrazine, as well as the various toxicological effects on human health.
2. to provide, even for information purposes, other physico-chemical characteristics of the water studied (pH, electrical conductivity, nitrates, etc.).
3. is it possible to provide information on the geological or hydrogeological structure of irrigation wells?
4. P3, L139: Since atrizine was the only substance measured in water samples, sub-heading 3.1 should be replaced. Water quality by 3.1. Concentration of atrazine in ground and surface water.

Overall statement

The study requires major revisions.

 

Comments for author File: Comments.pdf

Author Response

1. to present the physical and chemical properties of atrazine, as well as the various toxicological effects on human health.

 

Thank you for the question. We included additional information on various health outcomes

Lines: 79-84: “In addition to the studies that reported association between atrazine exposure and pediatric cancer, there are studies that identified that atrazine is associated with fetal deaths, pre-term births, neurologic disorders, and endocrine disorders in humans [11]. Additionally, several pre-clinical studies suggest that atrazine is associated with alternations in metamorphosis, reduced immune function, and abnormalities in sex hormones [12].”

 

1. to provide, even for information purposes, other physico-chemical characteristics of the water studied (pH, electrical conductivity, nitrates, etc.).

 

Thank you for the question. The atrazine water quality data included in this study was obtained from 3 open-source databases that vary across time and space. As water quality observations do not align in a spatio-temporal pattern, we will not be able to incorporate any information on physio-chemical properties in this study.

 

1. is it possible to provide information on the geological or hydrogeological structure of irrigation wells?

 

Thank you for the question. Due to the complexity of the water quality data, we will not be able to discuss the geological/hydro-geological structure of the irrigation wells. We are currently working on the geological/hydro-geological aspects of the irrigation wells.

 

1. P3, L139: Since atrizine was the only substance measured in water samples, sub-heading 3.1 should be replaced. Water quality by 3.1. Concentration of atrazine in ground and surface water.

 

Thank you. We updated the section header on line 184 with “Surface and groundwater atrazine concentrations”

Round 2

Reviewer 3 Report

Water

 

 

Manuscript Number: water-1396802-v2

Title: Association between aqueous atrazine and pediatric cancer in 2 Nebraska

 

Reviewer' comments:

Overall statement of the article

The paper, water-1396802 “Association between aqueous atrazine and pediatric cancer in 2 Nebraska ” submitted to Water Journal for publication, aims to to evaluate the association be-59 tween aqueous atrazine and pediatric cancer.

The paper contains 5 keywords:  Watersheds, atrazine, pediatric cancer, herbicides, water quality.

This work is divided into 4 distinct parts: (i) Abstract, (ii) Introduction, (iii) Material and Methods, (iv) Results  and (v) Conclusion.

The paper has 1 table and 2 figures. There are 31 references, which are from 1997 to 2020. The majority of the references are internationally evaluated and published in peer-reviewed journals.

According to the authors,statistically significant associations exist between atrazine surface water concentrations, atrazine groundwater concentrations, and the incidence of pediatric cancer in Nebraska.

 

Overall statement

The authors replied to the various comments made by the reviewer. They justified their answers and scrupulously worked on each of the comments. The paper should be accepted to be published in the journal.