How Per- and Poly-Fluoroalkyl Substances Affect Gamete Viability and Fertilization Capability: Insights from the Literature
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe review paper “Do PFAS affect gamete viability and fertilization capability? Insights from the literature“ is in the scope of the Special Issue The Role of Endocrine-Disrupting Chemicals in the Human Health of Journal of Xenobiotics. In focus of the paper are PFOA and PFOS, compounds that are classified as endocrine disruptors. The authors report the main findings on the effects of PFAS exposure on gamete competence and fertilization ability. The article provides an overview of recent literature and the abstract states the main results and conclusions of the paper. The English language is appropriate and understandable. However, I suggest that this paper should not be published in the Journal of Xenobiotics (IF=6.0). A review paper is more than a literature overview - it must include an in-depth critical review of the literature. In a systematic review with a specific research question, the research methods used should be clearly described. Ideally, the research methods, the databases searched, and the keywords used for the literature search should be described.
Some of the most important and less important notes are quoted below:
No reference is made to any figure or table in the text.
All abbreviations used in the figures (or tables) should be understandable without reading the rest of the text (e.g. Figure 3).
Ln 59 – 60 “The body eliminates PFAS compounds primarily through urine and secondarily through menstruation, pregnancy, and lactation” – please explain, rephrase
Ln 95 – 96 “PFOS is a stronger agonist compared to PFOA [22]. This is due to the presence of carboxylic acid, instead of sulfonic acid” – incorrect statement
Too large parts of the text are taken from only one literature source – e.g. 72 – 82 all from reference 18; ln 184 – 194 all from reference 36; ln 202 – 210 all from reference 38; ln 220 – 231 all from reference 40; ln 326 – 345 all from reference 47; ln 371 – 387 all from reference 46; ln 572 – 594 all from reference 53….
Figure 6 – for this type of article (related to the topic) it would be better to show the effects of PFAS on human embryo development (from zygote to blastocyst). The same applies to Figures 4 and 5.
It is not usual to start a conclusion with a picture.
Author Response
Please see attached PDF
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe proposed manuscript is well-writtem and informative. Its extensive use of tables detailing various effects provides valuable insights into both animal and in vitro studies, presenting comprehensive information on PFAS doses/concentrations, species, and observed results. These tables, complemented by high-quality figures, make the key findings easily accessible and comprehensible to readers.
I have only a few suggestions which I think would additionally improve the manuscript.
Consider adding a new section following the introduction to elucidate the literature search process. This section should detail the used keywords, inclusion criteria, and databases searched to provide more information about the research methodology.
I have two suggestions for improving the tables. For in vitro studies, consider including a column for cell type. Also, condense the information in the "Observed effects" column of all the tables into shorter bullet points for better readability.
Consider inserting Figure 8 between the main text and the conclusion subtitle. This placement will draw more attention to the conclusion and clearly separate it from the rest of the text.
Author Response
Please see attached pdf
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe present review of literature by C. Lockington and L.A. Favetta deals with the toxic effects of poly-fluoroalkyl substances (PFAS)on gamete viability and fertilization capability.
General Comment
The present review is intended to be inserted in a JoX issue dealing with endocrine-disrupting compounds (EDC). It appears that only part of PFAS effects (§2 and Table 1) is through endocrine-disrupting effects (Inhibition of GnRH secretion leading to a decrease in pituitary LH and FSH secretion and, consequently, to adverse effects on ovarian or testicular steroidogenesis). It is described in the review that the vast majority of effects are exerted on gametes (§3 and §4) or embryos (§5). It is interesting to describe all these mechanisms, but ED effects should be more clearly distinguished from reprotoxic effects.
Most data from the literature are presented as mere fragmented paragraphs, each relying on only one paper. The present Review would be more useful if an effort is made to render all the data clearer and articulated in original Figures.
Specific Comments
Title: Since it is well recognized that PFAS affect reproduction, it would be better to write « How poly-fluoroalkyl substances (PFAS)affect gamete viability and fertilization capability; Insights from the literature.»
Line 23-24: The meaning of the last sentence of the abstract is not clear
Line 31: « short-chained (<7 carbons) and long-chained (>7 carbons) » ; what about those with exactly 7 carbons? Short or long?
Line 32: « … are harder for the body to excrete » could be « are less efficiently excreted ».
Line 34: add « … both comprising 8 carbons (figure 1) ».
Figure 1 is unduly sophisticated (it is already present in previous articles and reviews). This is probably due to the pleasure of using Biorender. The same is true for Figures 2, 4, and 8.
Line 40: No poly-fluoroalkyl substances with less or more than eight carbons ?? Contradict the previous sentence line 31.
Line 41: replace « … on the binding site on the terminal carbon » by « at the terminal carbon ».
Lines 46-48: It is not clear why PFAS are specifically persistent in the atmosphere, as it is indicated later in the paper that it is also persistent in water and in various organs.
Line 49: Do PFAS have both hydrophobicity and lipophobicity? see https://doi.org/10.1038/s41370-023-00545-x.
Lines 41-55: Very short sentences that are not articulated for a clear explanation. In consequence, ref 1 cited 9 times in 15 lines without a logical goal. The same is true for other references cited repetitively in other paragraphs (ref 18 cited 6 times in a single paragraph, lines 72-82).
Line 60: Do you mean that the body excrete PFAS towards the fetus through the placenta (« pregnancy »)? Is there any indication of newborn or placenta contamination at delivery?
Line 63: do you mean elimination from the body or from the environment?
Line 66: « blood ovarian follicle barrier »
Line 70: Does the enterohepatic circulation of PFAS favor their accumulation in the liver, and does it provoke liver damage in the long term?
Lines 83-84 are not clear. Is it the expression or activity of nuclear receptors that is inhibited?
Line 96: why does the presence of carboxylic acid, instead of sulfonic acid, explain the stronger activity of PFOS compared to PFOA?
Line 100: « other nuclear pathways… » not methods
Lines 131 and 139: If 228ng/ml is an exceptionally high concentration of PFAS (line 131), it would be necessary for a 60kg-person to drink 60000 liters per day of this highly contaminated water to get 200mg/kg/day (line 131). There must be an error somewhere (maybe in my calculation).
Line 144: If PFAS have a high affinity for proteins, in particular serum albumin, which is highly abundant, this would explain their rather weak toxicity in spite of their very long half-life in the body.
Line 152 : Chapter 2 is the one centered on the endocrine-disrupting effects of PFAS (not direct toxic effects on gametes and embryos as the other chapters. This should be acknowledged to facilitate reading of the review.
Figure 2 is very basic and not necessary
Lines 162-175: This paragraph describes the data from one paper (Du et al. [33]) that is cited seven times in fifteen lines because the facts are briefly presented one by one without a logical explanation to follow the reasoning. This is also true in many other paragraphs.
Line 174: Replace « found » with « thus concluded.» This is not an additional fact but the conclusion of their study.
Lines 178-179: It is not logical that reduced GnRH expression led to increased LH mRNA since GnRH is known to stimulate pituitary LH (and FSH) secretion.
Chapter 2.1 GnRH is difficult to read as it gives a long list of individual facts. A figure to explain the logic and links between these facts would be welcome.
Line 282 ; Table 1 : « Rattus rattus » not « Rattis »
Line 411; Table 2: It would be useful to homogenize the dose units (molarity, weight/volume, or both) for comparison.
Line 426: « The stimulation by LH of the AC-PKA-CREB-StAR leads to increased cholesterol entry in the mitochondria and hence to increased testosterone synthesis by Leydig cells .» might be more precise
The long paragraph (lines 508-571) relies only on one single paper (ref 12). In a Review, it is expected that the authors wrap up data from various papers and make them comprehensible as a whole. I suggest you prepare a figure to summarize their data (there is no such figure in their paper) and, eventually, combine them with data from other papers.
The paragraph (lines 572-594) relies on one single paper (ref 53). By adapting (and completing) Figure 7 in ref 53, you could shorten and clarify this paragraph and the previous ones in your own Review.
Comments on the Quality of English LanguageAlthough the authors come from an English-speaking area, their language could be improved. As my own mother tongue is NOT English, I prefer not to correct these imperfections myself.
Author Response
Please see pdf attached
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors responded to all comments and queries and significantly improved their paper. The manuscript has been sufficiently improved to warrant publication in JoX.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors have considered all my comments and, in my opinion, positively amended their manuscript, which should be accepted for publication.
Just a few remarks that the authors could consider:
line 2 add a hyphen after per in the title
line 57 "routes" instead of "methods"
line 192: "GnRH" instead of "GrRH"
line 258: "the" instead of "our"
