If a published study reporting MNP in tissues that were previously collected by different researchers (e.g., tissue storage bank), should the results be trusted if there were no appropriate field blanks collected concurrently with the tissue collections? (please explain)

Answer Explanations

• It depends (please explain the scenarios where is does and does not matter)

  Expert 9
  While gold standard studies would include appropriate field blanks collected concurrently with tissue collection, in my view this does not render completely invalid studies based on previously collected samples that did not collect appropriate field blanks at the time. The conditions under which such samples were collected and stored should be considered and for example where these involved minimal plastic contact, these could be considered more fleaibale than those where plastic contact was greater. It would also be possible to prepare retrospective field blanks where the present day researchers mimicked the condiitions under which the original samples were collected and stored.
• No

  Expert 3
  There is no clear way to determine the origin of these fragments and the quantified MNPs may derive from the materials used for sample collection/storage, the operator, atmospheric deposition, reagents, etc., and the lack of controls and blanks cannot ensure the origin of said materials. 
• No

  Expert 2
  In my opinion, the results reported in studies that analyze tissues collected by different researchers   for micro and nanoplastics without the use of appropriate field blanks should be interpreted with caution, as they cannot be considered fully reliable. Having field blanks are essential to account for background contamination, which is a major concern given the ubiquity of plastics in the environment and laboratory settings. Because the tissues were not originally collected with MNP analysis in mind, contamination could have occurred at any stage of collection, handling, or storage, and without concurrent blanks there is no way to distinguish true environmental MNPs from artifacts introduced later. Such studies may still provide qualitative information into the possible presence of MNPs in biological tissues, but their quantitative results cannot be trusted as accurate or conclusive evidence of MNP presence. 
• No

  Expert 7
  The reported MNP could be from background contamination. 
  Filed blanks are important as they help identify contamination from airborne microplastics, tools, containers, lab environments, clothing, cross-contamination, and so on. 
  Without field blanks, it's not certain if the reported MNPs came from the biological sample itself or from the background contamination. 

  
  
• It depends (please explain the scenarios where is does and does not matter)

  Expert 4
  This would first of all depend on the purpose of the study. If the purpose of the study is to report on the MNP in the tissues without any further study aim, then no field blanks need to be available. It should be noted that the added value of this scenario would be limited.
  If the purpose of the study goes beyond this aim, then proper blanks should be included, considering the factors that might affect the analytical results. For example, storage time might be a factor of relevance, the medium that is stored could be of relevance, the method used for samplg, etc. In all cases appropriate blanks are required to make the results trustworthy.
  On an additional note: I presonally think that it is also valuable when it is reported that the authors indicate that they have paid attention to this issue, even when no solution to the problem was available.
• It depends (please explain the scenarios where is does and does not matter)

  Expert 1
  I would be skeptical of those data.  If samples were collected in the past by some other researchers for some other purposes, data can be spurious due to contamination issues.  Unfortunately, many researchers are not aware of such contamination, but report results.  Despite many researchers recently try to provide all quality assurance and quality control, which is related to laboratory side of analysis, samples collected in the past may not be in a controlled environment and QA/QC for sample collection is not provided
• No

  Expert 5
  Microplastics are ubiquitous in the environment. Without an appropriate background measurement, one cannot judge if the microplastics originate from the biological sample or the sampling environment.
• It depends (please explain the scenarios where is does and does not matter)

  Expert 6
  Such kind of research could be useful if field blank can be reasonably repeated. The results should be clearly discussed that there is no concurrent control, and any learning is expletory. There should be no definitive conclusion or implementation draw from the study. 
• It depends (please explain the scenarios where is does and does not matter)

  Expert 8
  I'm tempted to answer no, but there are cases (probably rare) in which the background contamination by collection and storage might be eliminated.