PLOS responds to PNAS study detailing the growth of peer review integrity issues

A new PNAS study uses openly available articles to map the scale of paper mill and peer review ring activity across scholarly publishing. Three facts give essential context:

1 An industry-wide threat, not a PLOS-specific problem

Paper mills have challenged many publishers for years. PLOS counters them through rigorous pre- and post-publication checks and joint initiatives with COPE, the STM Integrity Hub, and United2Act. The PNAS findings expand the toolbox for detecting misconduct and confirm why collective action remains vital.

2  Openness made the analysis possible

The authors focused on PLOS One for a case study because we publish rich, machine-readable metadata—including the handling editor for every article. Transparency is a deliberate feature of our open science mission: scrutiny strengthens integrity.

3  Our actions to safeguard research integrity

The PNAS case study includes issues PLOS had already acted on through prior investigations into paper mill activity and peer review manipulation, including editor–author networks. These earlier actions led to the removal of editors from our boards and the retraction of affected articles before the study’s publication.

PLOS continuously strengthens its integrity screening in response to emerging risks. Enhancements made between 2021 and 2025 have enabled PLOS One to identify and decline concerning submissions before publication, and this work is ongoing as we continue to evolve our safeguards to address new and emerging threats.

Editorial board integrity is safeguarded through careful vetting of members. Manuscripts are assigned to editors via industry standard algorithms or by experienced staff; Authors cannot select editors to handle their submissions and concerns about editor conduct are investigated promptly and addressed decisively.

Our commitment
PLOS is committed to improving the ways in which research is discovered, assessed and recognized for its academic rigor, transparency, and utility to the broader scholarly community.We will continue to refine our safeguards, share best practice with the wider community, and keep stakeholders informed of significant developments. We thank the PNAS authors for leveraging PLOS’ open data to advance joint defences against organised research fraud.

Veronique Kiermer

Chief Scientific Officer, PLOS