Hits on Google Scholar when searching for the name of the institute that performed NGS limited to the time period of 2010–2013 and requiring an additional match to the species that were reported to contribute miRNAs to the samples.

We reason that a study published in this time period could have been handled at the same time as the human and porcine breast milk samples. The number of Google Scholar hits that contain sequencing or NGS in title or abstract is indicated in parentheses. Please note, however, that contaminants can be introduced during any step of the experimental procedure and not just during sequencing and, therefore, the hits on Google Scholar are the most indicative measure for this analysis. Data is also available as Table B in S2 File.