Do you recommend any changes to the best practices outlined in the Conclusions section?

Answer Explanations

• Yes (please explain)

  Expert 9
  I would replace the statement "Should the role of microplastic research be to protect health or to avoid alarmism? If the answer is to protect human health, which seems axiomatic, the field should reconsider currently established techniques, in favor of those that quantify metrics health protectively. The current status quo appears to generally favor underestimation.",  with a statement that the role of MP research is to report as accurately as possible its findings about the presence of MPs in biological tissues. It is neither job of researchers to protect health or avoid alarmism - though both are desirable outcomes."
• No

  Expert 3
  Presently, it is an adequate summary. 
• Yes (please explain)

  Expert 4
  I find Table 1 very informative and am of the opinion that this Table could be given a more prominent position in the manuscript, supplemented with some discussion on the contents of Table 1.
  What might be added to the Conclusion is the need for harmonized Guidelines for executing and reporting of all steps in the analysis of plastics in complex matrices like biological tissues. Even provisional aspects of the guidance needed, could be mentioned here in the form of an extended conclusions section.
• Yes (please explain)

  Expert 1
  The conclusion simply states that there is still no known silver bullet method available for all plastic types.  The conclusion is true and correct.  What needs to be done to overcome this issue of a lack of standardized method is more important.  The author may recommend development of a standardized method for MNPs by regulatory agencies.  In recent years, pyrolysis GCMS is gaining popularity as it alleviates several QA/QC issues.  Author may call for some unified action among MNP researchers for the development standard methods and harmonization of labs.
  
  My second suggestion is define the scope of MNPs.  Currently, there is no limit about different type of plastics analyzed.  Some reports indicate more than 30 types of plastics in commerce.  It is still unclear how many types of MNPs are there.  Often in the literature we come across cellulose, tire wear particles as MNPs.  Are they really plastics?  Also, in the literature copolymeric types of MNPs (e.g., PP-PE) are reported.  How many such combination of copolymers exist?  Some definition of scope of MNPs is needed to set the stage.  I think this article may help create those boundaries with regard what constitute MNPs and what are not MNPs (cellulose, which can arise from paper; tire wear particles are rubber materials).  
  
  In terms of Figure 1 showing best practices, I would not state that pyrolysis GCMS issues related to PE and PVC signals cannot be overcome.  There is a scope of improving that aspect.  Or at least you may use qualifying statements that the issue is reported "currently" and efforts are needed to overcome.
• Yes (please explain)

  Expert 2
  Add information about identified existing gaps and future needs in this area of expertise.
  Rename Table 1 or try moving it to a section from Results and Discussions
  
  
• Yes (please explain)

  Expert 5
  See suggestion for Table 1 below.
• Yes (please explain)

  Expert 8
  In Knowledge Gaps section, I found line 620 to be hypocritical to the best practice of "not reinventing the wheel". Novel methods are important and should be encouraged, like this section. Perhaps clarify in the earlier section that you dont mean to halt innovation, but instead you are suggesting to read the literature before you begin and use what has worked before.
• Yes (please explain)

  Expert 6
  "Red is for critical issues observed with no known way to overcome" It is better to include timestamp here, as issues are not resolving now, could be solved in the future.