Concentration and Variability of Urinary Phthalate Metabolites, Bisphenol A, Triclosan, and Parabens in Korean Mother–Infant Pairs

Round 1

Reviewer 1 Report

Information on individual variability of chemical exposures can provide insights into toxic chemical metabolism and a basis for judging whether the concentration data are more reliable. This study may provide meaningful data on environmental exposure study.

Abstract

According to the author's instructions, “Abbreviations should be defined in parentheses the first time they appear in the abstract, main text, and in figure or table captions and used consistently thereafter”. It would be better to consider spelling out several abbreviations (MEP, MnBP, MiBP, MBzP, MiNP, MEHP, MEOHP, MEHHP, MECPP, MCOP, MP, EP, and PP), if possible.

Introduction

Line 59: 12 h → 12 hours (“h” in other sites would be changed to “hour(s)”.

Material and methods

For the study subjects, was the age for infants set?

For infants’ characteristics, were the information on gestational weeks, birth weight, and health status collected?

Did the authors collect the information on breastfeeding of subjects (frequency, periods, etc…)

Figure 2. For the number of significant digits in the y-axis, is three significant figures required? Moreover, it would be better to revise the indistinct figures.

Discussions

This study focused on the inter- or intra-individual variability of several chemicals. The authors should state firstly on its results in the discussion section. A comparative discussion about the detected values is of secondary discussion points.

It would be better to state which way(s) are the best for evaluation on the safety of each chemical (about sampling time).

Author Response

Information on individual variability of chemical exposures can provide insights into toxic chemical metabolism and a basis for judging whether the concentration data are more reliable. This study may provide meaningful data on environmental exposure study.

1. Abstract

According to the author's instructions, “Abbreviations should be defined in parentheses the first time they appear in the abstract, main text, and in figure or table captions and used consistently thereafter”. It would be better to consider spelling out several abbreviations (MEP, MnBP, MiBP, MBzP, MiNP, MEHP, MEOHP, MEHHP, MECPP, MCOP, MP, EP, and PP), if possible.

Following your comment, we have provided a description of abbreviations in the Abstract section for MEP, MnBP, MiBP, MBzP, and MCOP (page 1). All of the abbreviations used in our manuscript now follow journal guidelines.

1. Introduction

Line 59: 12 h → 12 hours (“h” in other sites would be changed to “hour(s)”.

In response to your comment, we have revised it. Please see page 2, line 60 (in yellow) in the revised manuscript.

1. Material and methods

For the study subjects, was the age for infants set?

For infants’ characteristics, were the information on gestational weeks, birth weight, and health status collected?

Did the authors collect the information on breastfeeding of subjects (frequency, periods, etc…)

Thank you for your thoughtful comments. As this study is a follow-up study of new mothers and newborns who received breast milk, the average age of the infants was 11.4 months in this study. Infants' birth weight, gestational age, and breastfeeding information were reported in previous studies (Kim et al., 2020). The current age and weight of the infants are presented in Table 1 in the revised manuscript.

In light of your comment, we added information on infant birth weight and breastfeeding periods in Table1. Please see page 5 in the revised manuscript.

1. Figure 2. For the number of significant digits in the y-axis, is three significant figures required? Moreover, it would be better to revise the indistinct figures.

Per your comment, we have revised Figure 2. Please see pages 15–17 in the revised manuscript.

1. Discussions

This study focused on the inter- or intra-individual variability of several chemicals. The authors should state firstly on its results in the discussion section. A comparative discussion about the detected values is of secondary discussion points.

It would be better to state which way(s) are the best for evaluation on the safety of each chemical (about sampling time).

Based on your comment, we have reconstructed the Discussion section and added these details. Please see page 18 in the revised manuscript. Additionally, we have clarified the sampling times in the Material and Method section on page 3, lines 95-96.

Reviewer 2 Report

This article is well-written and provides some findings on the concentrations and variability of 15 toxic chemicals in urine samples in Korean mothers and their infants. 

These results demonstrated that the concentration of toxic chemicals in the infants was higher than that in the mothers, and the concentrations were significantly correlated with those in the infants.

However, the result section must be improved.

1. Please provide a description of the abbreviation in Table 1. Table 2 with percentile doest help to see the variation between groups and variable. I would recommend providing only mean and SD values.
   Table 2 should be placed after Table1.
2. p10. Please provide a title for this figure, including the stats used and the abbreviations. Please remove the 3 numbers after the point (example: fig. a : 140 not 140.000 ) as it is inadequate to show them.
3. Please provide only 2 significant numbers for this Table. Ex: 0.45 not 0.448; 0.093 is correct.
4. Please improve the visual quality of this figure 2a and 2 b. We cannot see well the data using this format.

Author Response

This article is well-written and provides some findings on the concentrations and variability of 15 toxic chemicals in urine samples in Korean mothers and their infants. 

These results demonstrated that the concentration of toxic chemicals in the infants was higher than that in the mothers, and the concentrations were significantly correlated with those in the infants.

However, the result section must be improved

1. Please provide a description of the abbreviation in Table 1. Table 2 with percentile does not help to see the variation between groups and variable. I would recommend providing only mean and SD values.
   Table 2 should be placed after Table1.

Thank you for the suggestion. Per your suggestion, we added a description of the abbreviations for both Tables 1 and 2 on pages 6 and 8, respectively, in the revised manuscript.

We also agree with your comment on the SD values and have provided these details in the revised Table 1 (page 7).

1. p10. Please provide a title for this figure, including the stats used and the abbreviations. Please remove the 3 numbers after the point (example: fig. a : 140 not 140.000 ) as it is inadequate to show them.

Per your comment, we have added a title and listed the definitions of the abbreviations. Per your suggestion, we have also removed the excess numbers and revised Figure 1 accordingly. Please see page 9 in the revised manuscript.

1. Please provide only 2 significant numbers for this Table. Ex: 0.45 not 0.448; 0.093 is correct.

Following your recommendation, we have revised values in Table 3 to include only two decimal places. Please see page 10 in the revised manuscript

1. Please improve the visual quality of this figure 2a and 2 b. We cannot see well the data using this format.

Following your comment, we have revised Figure 2a and 2b. Please see pages 15–17 in the revised manuscript

Round 2

Reviewer 2 Report

Thank you for revising the manuscript according to my comments.