PLOS has issued a statement in response to a study published in Proceedings of the National Academy of Sciences (PNAS) that examined the scale of paper mill operations and peer review manipulation across scholarly publishing. The analysis, which used openly available articles, identified coordinated misconduct patterns such as peer review rings.
The organisation noted that such activity represents an industry-wide challenge rather than a publisher-specific issue. It outlined existing measures to counter misconduct, including rigorous pre- and post-publication checks and participation in collaborative initiatives with the Committee on Publication Ethics (COPE), the STM Integrity Hub, and United2Act. PLOS stated that the PNAS findings provide additional tools to detect such practices and reinforce the need for sector-wide cooperation.
The study’s focus on PLOS One was attributed to the journal’s openly accessible, machine-readable metadata, which includes the handling editor for each article. PLOS stated that this transparency is an intentional component of its open science approach, enabling external scrutiny to strengthen research integrity.
According to the organisation, the specific cases identified in the PNAS study had already been addressed through earlier investigations into paper mill activity and peer review manipulation, leading to the removal of editors from boards and the retraction of affected articles prior to the study’s release. Between 2021 and 2025, PLOS implemented enhanced screening processes that have enabled the identification and rejection of concerning submissions before publication. Editorial board integrity is maintained through vetting of members, algorithmic or staff-based assignment of manuscripts, and prompt investigation of concerns regarding editor conduct.
PLOS reaffirmed its commitment to strengthening safeguards, sharing best practices, and maintaining transparency in scholarly publishing, adding that it welcomed the use of its open data in research aimed at improving collective defences against organised research fraud.
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