Out of date Science paper piracy site Sci-Hub shares lots of retracted papers 85 percent of invalid papers continue to be shared after they've been retracted. John Timmer Jan 7, 2025 2:39 pm | 7 Keeping track of when a paper has been retracted can be a challenge. Credit: pablohart Keeping track of when a paper has been retracted can be a challenge. Credit: pablohart Story textSizeSmallStandardLargeWidth *StandardWideLinksStandardOrange* Subscribers only Learn moreMost scientific literature is published in for-profit journals that rely on subscriptions and paywalls to turn a profit. But that trend has been shifting as various governments and funding agencies are requiring that the science they fund be published in open-access journals. The transition is happening gradually, though, and a lot of the historical literature remains locked behind paywalls.These paywalls can pose a problem for researchers who aren't at well-funded universities, including many in the Global South, which may not be able to access the research they need to understand in order to pursue their own studies. One solution has been Sci-Hub, a site where people can upload PDFs of published papers so they can be shared with anyone who can access the site. Despite losses in publishing industry lawsuits and attempts to block access, Sci-Hub continues to serve up research papers that would otherwise be protected by paywalls.But what it's serving up may not always be the latest and greatest. Generally, when a paper is retracted for being invalid, publishers issue an updated version of its PDF with clear indications that the research it contains should no longer be considered valid. Unfortunately, it appears that once Sci-Hub has a copy of a paper, it doesn't necessarily have the ability to ensure it's kept up to date. Based on a scan of its content done by researchers from India, about 85 percent of the invalid papers they checked had no indication that the paper had been retracted.Correcting the scientific recordScientific results go wrong for all sorts of reasons, from outright fraud to honest mistakes. If the problems don't invalidate the overall conclusions of a paper, it's possible to update the paper with a correction. If the problems are systemic enough to undermine the results, however, the paper is typically retractedin essence, it should be treated as if it were never published in the first place.It doesn't always work out that way, however. Maybe people ignore the notifications that something has been retracted, or maybe they downloaded a copy of the paper before it got retracted and never saw the notifications at all, but citations to retracted papers regularly appear in the scientific record. Over the long term, this can distort our big-picture view of science, leading to wasted effort and misallocated resources.Some researchers based in India suspected there might be an additional reason retracted papers are still being cited: Sci-Hub. Sci-Hub works a bit like a combination of cache and aggregator for published materials. Whenever it gets a request for a paper that's not already in its database, it uses leaked login credentials to go to the website of whatever journal published the paper and obtain a copy. If it already has a copy, however, it will simply serve that up instead. This leaves open the possibility that it will have obtained a copy of a paper prior to its retraction and continue to distribute that copy after the paper has been retracted.To check this, the researchers obtained a list of nearly 17,000 retracted papers and searched for them on Sci-Hub. They then visually examined the documents that were returned. They found that 85 percent of them contained no indication that the paper had been retracted. "The availability of [unlabeled retracted articles] in the field of health sciences is particularly high," they note, "which indicates a significant risk of their unintended use and further citation in future research."Staying up to dateWhile corrections are less severe than retractions, they're likely to suffer a similar problem. And corrections will often involve the technical details of a paperthe experimental approaches or raw data that will be critical for anyone wanting to replicate or extend previously published results. So, if anything, their impact will be more significant.It's worth noting that this was already recognized as a problem even in the absence of Sci-Hub, and a system called Crossmark was developed to make it easy to find the most up-to-date version of a paper, including any corrections or retraction notices. Of course, not all publishers use Crossmark, and making it easy to use doesn't guarantee researchers will find the time to go through what might be a massive library of reference papers and check each one before publishing.But, given that Sci-Hub is an automated system, it doesn't suffer from the lack of free time or motivation of an actual living researcher. In theory, there's nothing to prevent it from being updated to incorporate a check of whether its cache contains the most recent version of a paper whenever it's requested.Accountability in Research, 2025. DOI: 10.1080/08989621.2024.2446558 (About DOIs).John TimmerSenior Science EditorJohn TimmerSenior Science Editor John is Ars Technica's science editor. He has a Bachelor of Arts in Biochemistry from Columbia University, and a Ph.D. in Molecular and Cell Biology from the University of California, Berkeley. When physically separated from his keyboard, he tends to seek out a bicycle, or a scenic location for communing with his hiking boots. 7 Comments