Metal and Pesticide Assessments of Imported and Locally Cultivated Rice (Oryza sativa) in Senegal

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The proposed paper by Ndiaye et al. aimed to assess heavy metals, pesticides, ash, fat, humidity, carbohydrate and protein level in rice using rice samples from India, Thailand, South America, Vietnam, and China. The paper covers very important topic. However, it would benefit from certain corrections and polishing.

Consider enhancing the abstract by incorporating a sentence outlining the health hazards associated with the examined metals and pesticides. Additionally, present the ranges of measured levels of these substances in brackets alongside their respective mentions in the abstract. Fat, humidity, and carbohydrate level had also been measured but were not mentioned in the abstract, which should be corrected.

In the Introduction section, it is crucial to describe the health hazards posed by metals and pesticides, particularly acknowledging that certain substances such as As, Cd, and Ni are classified as human carcinogens by IARC. To ensure comprehensive coverage, briefly discuss the effects on human health separately for metals and pesticides. Moreover, the authors should clarify the rationale behind incorporating these specific metals and pesticides into their study. It would be beneficial for readers to understand whether these pesticides are commonly used in rice cultivation, providing context to the relevance of their measurement in rice samples.

In the Sample Preparation section, include the approximate volume of nitric acid placed into the digestion vessels.

The Analytical Techniques section lacks a description of the method used for determining toxic metals. I recommend the authors restructure the Material and Methods for improved clarity. Instead of grouping methods by preparation and measurement, consider organizing them into sections: 1) Preparation and Measurement of Toxic Metals, 2) Preparation and Measurement of Pesticides, and 3) Preparation and Measurement of Protein, Lipids, and Glucose.

Include the essential missing details such as limits of detection (LOD) and limits of quantification (LOQ), recovery values, as well as the standards utilized for calibration and quality control to enhance the comprehensiveness of the information. The recovery value is presented in one of the tables, but it should also be included in the M&M section.

In Table 2, consider highlighting the highest measured metal concentration for each region, using bold text or another marking system. For instance, the Al content in rice from India notably surpasses that in samples from other countries. Similarly, the B levels in the rice from Senegal exceed those observed in rice from other countries. The highest metal concentrations should also be marked in the Table 3 as well as the Pesticide content in table 4. These regional differences should also be discussed in the Discussion section and highlighted in the conclusion. The authors should also consider applying statistical analysis to assess the significance of the difference between these values, to add a quantitative layer to the interpretation of regional differences.

It is essential to ensure consistency in the use of abbreviations throughout the manuscript. Once introduced, abbreviations should be consistently employed in subsequent references. For example, within the current manuscript, there is a notable inconsistency in how "arsenic" is presented, with variations occurring between the full name and its abbreviation.

Comments on the Quality of English Language

Minor editing required. 

Author Response

We thank the reviewer for the comments. Our work's judgment was harsh but fair and motivated us to do extensive revisions in the manuscript. All the manuscript was revised for the use of English and the terminology used. All the typos and other related mistakes were corrected. More information was provided in the abstract section to complete parameters used in this study, while some parts were re-written to meet the standards of an International Journal.

We want to mention here that the entire manuscript has been thoroughly revised and not just the parts that were pointed out by the reviewers.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript (applsci-2832896) titled "Metals and pesticides assessments of imported and locally cultivated rice (Oryza sativa) in Senegal" presents a comprehensive assessment of heavy metals, pesticides, ash, and protein content in rice, comparing imported rice from India, Thailand, South America, Vietnam, and China with locally cultivated rice in Senegal. The study aims to address the dearth of information on contaminant levels in rice consumed in Senegal and offers insights into the health indicators associated with rice cultivation and consumption in Africa. While the study raises several important points, a major manuscript revision is needed before it can be considered for publication in the Applied Sciences Journal. Several major drawbacks to this manuscript are given below.

The abstract could benefit from more specific details about the methodology employed and the major findings. It lacks information on the sample size, sampling locations, and specific rice brands chosen for the study.

The manuscript lacks clarity on the specific methodologies employed for heavy metal and pesticide assessments. It is crucial to provide details on the analytical instruments used. Instrument models are missing, as well as manufacturer names, and the analytical procedure needs to be specified in more detail.

In addition, include the validation protocols and the values for validation parameters. Without this information, the reliability and reproducibility of the results are questionable.

The results regarding heavy metal concentrations in soils and rice are provided, but the absence of statistical analyses, such as significance testing or confidence intervals, makes it challenging to assess the robustness of the findings. Additionally, the protein content data lack statistical comparisons between imported and locally cultivated rice.

The identification of pesticide residues is an essential aspect of the study. However, the manuscript lacks details on the specific pesticides tested, their concentrations, and the analytical methods used. This study covered only a few pesticides due to the analytical limitations.  Namely, the authors only report the presence of four pesticides, leaving many others unassessed. This should be discussed.

The lack of reference to existing literature or relevant studies weakens the context for these interpretations. The authors should redo the literature search, additionally analyze the latest published works and update the reference list. Also, the references in the text should not be in superscript.

The potential impact of rice varieties and natural translocations on contaminant levels needs further elaboration and support from existing research.

The discussion mentions potential health risks but lacks a quantitative assessment of the risks associated with the detected levels of contaminants. Conduct a quantitative risk assessment, i.e., calculate the estimated daily intake of heavy metals and pesticides based on consumption patterns and compare it to established safe limits.

This manuscript does not have any figures, so the revised version should also consider graphically presentation of the results.

Many technical and grammatical errors need to be corrected, for example, it should not be "local", but "Local", etc.

In summary, several aspects, including methodology, statistical analysis, data interpretation, and referencing, need improvement to enhance the overall scientific rigor and validity of the study.

Author Response

We thank the reviewer for the comments. Our work's judgment was harsh but fair and motivated us to do extensive revisions to the manuscript. All the manuscript was revised for English and the terminology used. All the typos and other related mistakes were corrected. More information was provided in the abstract section to complete the parameters used in this study, while some parts were rewritten to meet the standards of an International Journal.

We wanted to let you know that the entire manuscript has been thoroughly revised not just the parts that the reviewers pointed out.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The article is devoted to the study of consumer safety of the current state of rice production, comparing local rice with imported rice in Senegal. The topic of contamination of the main food product (rice) is very relevant for a particular region. In principle, an article on a similar topic should and can be published in an international scientific journal. However, the correctness of sample selection, their repetition, and analysis methods raise doubts about the reliability of the results.

Key notes:

1. The introduction contains fragmentary information on individual pollutants. Authors may benefit from reading summaries: https://www.who.int, for example https://www.who.int/news-room/fact-sheets/detail/lead-poisoning-and-health or https:// www.who.int/news-room/fact-sheets/detail/arsenic.

2. The materials and methods section does not allow you to see a clear experimental design. I don't understand what the replication of studies is for each indicator.

3. The reliability of the method for determining the rice producer raises serious doubts. Questioning market vendors about the origin of food is not a very reliable method.

4. Research methods are described unsatisfactorily. There are a lot of methodological errors and outdated methods. The main disadvantage is that not all stages of determining the chemical composition are described.

5. The authors ignore international recommendations for studying the chemical composition of rice, standardized by the Codex Alimentarius Commission. Authors are required to review the standards and recommendations at https://www.fao.org/fao-who-codexalimentarius. Chemical analysis methods must comply with the standards - https://www.fao.org/fao-who-codexalimentarius/codex-texts/list-standards/en/. You need to read all documents that relate to types of pollutants (for example, individual metals, pesticides - https://www.fao.org/fao-who-codexalimentarius/codex-texts/dbs/pestres/pesticides/en/), as well as all standards that relate to rice (primarily CXS 198-1995 “Standard for Rice” CCCPL, 2019 or other more specialized documents, for example “Code of Practice for the Prevention and Reduction of Arsenic Contamination in Rice” CCCF, 2017). This is a fundamental remark.

6. The Results section contains a mixture of fragmentary characteristics from tables mixed with references to the literature. There are also general reflections of the authors on the process of growing rice, which relate to the problem under study indirectly. It is unacceptable. The results should contain only the authors' data (tables, histograms), but not speculation, generalizations or assumptions. You cannot include references to literature in the Results.

7. The data in the tables leads me to believe that the authors used single-shot studies. It is unacceptable.

8. The article does not contain any statistical processing of the results.

Overall, I cannot recommend the article for publication in this form. Incorrect sampling techniques, fragmentary descriptions of analytical methods, their inconsistency with the Codex Alimentarius, lack of statistical processing, and unfamiliarity of the authors with fundamental international standards and practices for the analysis of food toxicants must be eliminated.

Author Response

We thank the reviewer for the comments. Our work's judgment was harsh but fair and motivated us to do extensive revisions to the manuscript. All the manuscript was revised for English and the terminology used. All the typos and other related mistakes were corrected. More information was provided in the abstract section to complete the parameters used in this study, while some parts were rewritten to meet the standards of an International Journal.

We wanted to let you know that the entire manuscript has been thoroughly revised not just the parts that the reviewers pointed out.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

 

Authors presented the analysis of elements and pesticides in imported and locally cultivated rice (Oryza sativa) in Senegal. Although the rice is one of the most frequently analyzed food (due to the arsenic), there is a lack of research about rice from Senegal. However, the quality of the article is poor. There are several doubts in the methodology and the data are presented chaotically. The manuscript requires a thorough revision.

 

1.     Arsenic is a metalloid, not a metal. Please change this.

2.     Please unify significant numbers in the whole text.

3.     There is no uncertainties for all results. Please add this.

4.     Please use a hyphen for GC-MS and all hyphenated techniques (not a slash).

5.     There are no details about samples. There is a lack of number of samples from each country, market etc. as well the geographical coordinates for samples collected locally. Please add this to improve your discussion.

6.     Each methodology contains references to other work, and the parameters included in this manuscript are often insufficient to repeat the experiment. Please introduce key parameters for each procedure.

7.     There is a lack of many details, e.g. manufacturers of reagents, gases, calibration standards, grinders, digestion and combustion systems, analytical instruments, purification water systems. Moreover, there is a lack of many key parameters of these procedures. Please add these data.

8.     Line 91, I have doubt if it is possible to sieve rice grains through 2 mm sieve. Was it a full grain or milled?

9.     It is not clear which procedure was used to analyze the elements. Please described the whole procedure in details.

10.  Please describe in detail the validation results of all analytical procedures (elements, pesticides, proteins, lipids, etc.). Which CRMs were used?

11.  Table 1. You cannot use “not detected” as a limit. It must be clear if it is LOD or LOQ, and then you can write <LOD or <LOQ. It must be corrected.

12.  Please explain why different elements was determined for local rice (Table 1), imported rice (Table 2) and soils (Table 3)?

13.  Please explain why Al was not determined in soil?

14.  Please explain why pesticides were not determined in soil?

15.  Table 2, units are chaotically presented. Is it percentage of weight (% wt.)?

16.  Table 4, units must be added.

17.  I do not understand why high content of pesticides was not highlighted in discussion and conclusion. This observation should a thorough commented since it is most interested.

 

Author Response

We thank the reviewer for the comments. Our work's judgment was harsh but fair and motivated us to do extensive revisions to the manuscript. All the manuscript was revised for the use of English and the terminology used. All the typos and other related mistakes were corrected. More information was provided in the abstract section to complete the parameters used in this study, while some parts were rewritten to meet the standards of an International Journal.

We wanted to let you know that the entire manuscript has been thoroughly revised not just the parts that the reviewers pointed out.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

All changes and corrections made to improve the manuscript were appropriate. 

Author Response

We thank the reviewer for the valuable and constructive comments he brought to the manuscript.

Reviewer 2 Report

Comments and Suggestions for Authors

The revised version of the manuscript is acceptable.

Author Response

We thank the reviewer for the valuable and constructive comments he brought to the manuscript.

Reviewer 3 Report

Comments and Suggestions for Authors

The peer-reviewed article has improved significantly. However, many shortcomings remained uncorrected.

1. In the annotation, % must be rounded to tenths.

2. The statement on line 42-43 is not true (https://en.wikipedia.org/wiki/IARC_group_1_Carcinogens). You also need to check lines 64-63 very carefully. Negligence is unacceptable.

3. In the Results section, references to literature are not allowed (for example, lines 198-223).

4. How can you calculate the average of a column in Table 1 if some of the values are not precisely defined? The middle one needs to be removed.

5. Why did the authors add the last two columns to Table 2? They need to be removed.

6. Line 269: The concentration of chemical elements in the soil will differ over a distance of several meters. It is unacceptable to publish information without exact coordinates.

7. Lines 278-288 do not hold water. They definitely need to be removed.

Authors should be very careful about the formatting of the manuscript. The carelessness that is evident in the analysis of the manuscript may have been present both during sampling and during chemical analysis?

Author Response

We thank the reviewer for the comments. Our work's judgment was harsh but fair and motivated us to do extensive revisions in the manuscript. All the manuscript was revised for the use of English and the terminology used. All the typos and other related mistakes were corrected. More information was provided in the IARC section to complete arising questions in this study, while some parts were re-written to meet the standards of an International Journal.

Please find the responses to the individual comments below

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

I appreciate significant improvements in terms of the experimental parts as well as the visualization. Authors conducted a thorough revision of the manuscript and responded for all my comments however there are some inconsistencies:

1)    Authors stated that all units were corrected but I asked about significant numbers. They were not unified (see K in Table 2). Please unify them.

2)    Many details were not enclosed, e.g. manufacturers of reagents, gases, calibration standards, grinders, digestion and combustion systems, analytical instruments, purification water systems. Please add these data.

3)     Many key ICP MS parameters are still missing. Please add these details.

4)    Why were uncertainties or even SD estimated? Was each sample really prepared once?

5)    The style of some fragments of the section Materials and Methods should be improved. Paragraph 2.2 is differently written than the following one (2.3). Please unify your style e.g. avoid the imperative mood.

Author Response

We thank the reviewer for the comments. Our work's judgment was harsh but fair and motivated us to do extensive revisions to the manuscript. All the manuscript was revised for the use of English and the terminology used. All the typos and other related mistakes were corrected. More information was provided in the IARC section to complete the arising questions in this study, while some parts were rewritten to meet the standards of an International Journal.

Author Response File: Author Response.pdf