Thousands of scientists inflate their CVs with self-published studies that cost millions of dollars of public money

Three scientists have coined a rather scatological, yet revealing, term: PISS, short for Published In Support of Self. The acronym defines a disconcerting phenomenon. Specialized scientific journals that were once published every two weeks or weekly now churn out special issues every few hours. Previously, these monographs were selective and entrusted to a leading figure in a scientific discipline. Now, even the most mediocre researchers receive a flood of invitations to edit one of these countless special issues, which have become a multi-million dollar business.

Thousands of scientists seize the opportunity to publish studies under their own names and pad their CVs. The pool of science is in danger of filling up with PISS, warn the three researchers: Spanish engineer Pablo Gómez Barreiro, Italian economist Paolo Crosetto, and Canadian immunologist Mark Hanson.

A typical scientific study might involve a new treatment for a disease. Traditionally, such an advance was published in a journal specializing in that medical field, and interested readers would have to pay to access it. With the recent push for open access science, readers no longer pay; instead, the study’s authors must cover the publication fees — usually more than €2,000 ($2,300) from public funds — for each paper.

It’s a perverse incentive. Institutions require scientists to publish numerous studies in order to qualify for promotions and salary increases, and publishers earn more the more they publish. The result is thousands of irrelevant special issues flooding the field, crowding out high-quality science.

Spanish engineer Pablo Gómez Barreiro works at the Royal Botanic Gardens, Kew, in southern England. He recounts that around 2018, his email inbox began to fill with invitations to be an editor of special issues or to publish studies in them, as happened to hundreds of thousands of colleagues. Intrigued, Gómez Barreiro started snooping around online and came across two strangers who were also investigating the issue: Hanson and Crosetto.

The three researchers have just analyzed 110,000 special issues containing over a million studies published by five publishers between 2015 and 2025. Their conclusion: most scientists act properly, but even so, every year there are more than 1,000 special issues in which over a third of the studies are authored by the invited editors themselves. And that’s just in this small sample.

There are some very striking cases, Hanson explains. A special issue of the journal Processes (published by MDPI) includes 28 studies on the manufacture of biologic drugs. All but one are authored by the guest editor, Jochen Strube, from the Clausthal University of Technology in Germany. Another special issue from MDPI, this time in the journal Nutrients, contains 24 studies on diets to combat phenylketonuria, an inherited disorder. The guest editor, nutritionist Anita Macdonald, from Birmingham Children’s Hospital in the U.K., authored 23 of them. Some editors can pad their CV with a single special issue, achieving in one go what would normally take years of work.

Gómez Barreiro, Hanson, and Crosetto are calling for urgent action. “The cost of inaction is immense, lest we continue to piss hundreds of millions of research funds down the drain,” they warn. The three researchers set a generous threshold of 33% of self-authored studies for a special issue to be considered PISS. Their analysis found more than 16,000 papers authored by editors beyond that 33% threshold. Including that accepted percentage, the total exceeds 43,000.

“Assuming a conservative estimate of €2,000 in publication costs per study [charged by the publisher], between €33 and €87 million [$38 to $101 million] has been spent on PISS over 11 years,” laments the trio, who have only analyzed 900 of the 47,000 academic journals worldwide.

The three colleagues conducted this research in their spare time, as none of them work professionally in bibliometrics, the quantitative analysis of scientific literature. Mark Hanson is an immunologist at the University of Exeter in the U.K, while Crosetto works at the Laboratory of Applied Economics in Grenoble, France. A couple of years ago, the three of them, along with British anthropologist Dan Brockington, used sophisticated software to extract all the available information from the websites of major international publishers. Their conclusion at the time was that three companies exhibited particularly anomalous behavior, with a very high percentage of studies published in special issues: the Swiss journal Frontiers (69%), the Egyptian journal Hindawi (62%), and, above all, MDPI (88%), a corporate giant founded in Switzerland by the Chinese chemist Shu-Kun Lin.

That analysis confirmed that MDPI was failing across all indicators. While a prestigious publisher might need an average of 185 days to assess the quality of a study and authorize or reject its publication, MDPI only took 37 days and accepted more than half of the submissions. In the new analysis, one in eight special issues is classified as PISS. Eighty-seven percent of these suspect monographs belong to MDPI: about 12,200. The rest, mostly, belong to Frontiers: around 1,600. Both publishers defend their protocols and the quality of their studies.

Biologist Isidro Aguillo, head of the Cybermetrics Lab at the Spanish National Research Council (CSIC), is calling for these publications to be sanctioned, suggesting action could be taken, for example, by Spain’s National Agency for Quality Assessment and Accreditation (ANECA), the agency that reviews CVs to decide whether a university professor can be promoted to full professor or deserves salary increases. “The special issues of MDPI and Frontiers are a huge loophole. ANECA must explicitly exclude these works. The vice-rectorates for research at universities and similar bodies in public research organizations must identify careers built primarily on special issues and penalize them in the selection and promotion processes,” says Aguillo.

Of the 200,000 guest editors analyzed, some 28,000 participated in the PISS. Hanson points to some examples in Spain, such as a special issue on hydraulic engineering in the journal Water (MDPI), with seven of its eight studies authored by guest editor Pedro Luis Iglesias from the Polytechnic University of Valencia. Iglesias states that the main reason for concentrating so many of his works in that special issue was “to allow several doctoral students to publish their research results quickly and with reasonable review deadlines.” In his opinion, “the reviews received at MDPI have been, in many cases, as demanding as, or even more demanding than, those obtained from publishers not included in the analysis, such as Elsevier or Springer.” The underlying problem, Iglesias argues, is the current open access publishing system. “The real debate is not the existence of special issues, but the acceptance of a model in which the ability to publish is tied to payment by the author, which introduces obvious tensions,” he concludes.

The new analysis, however, highlights that the bigger problem lies with special issues that are less blatant. They don’t even need to cross the arbitrary 33% threshold. A report prepared for the Spanish Research Ethics Committee, which confirmed the “deliberate manipulation” of Juan Manuel Corchado’s CV — the rector of the University of Salamanca — pointed out that he had been the invited editor of 31 special issues in MDPI journals, with 76 studies published by MDPI.

The authors of that report on the rector, Emilio Delgado and Alberto Martín, bibliometrics experts at the University of Granada, analyzed how “MDPI professors” have proliferated in academia: scholars who advance quickly thanks to a CV built largely on this type of often superficial study. Their data are striking. In 2021, one in seven Spanish scientific studies was published in an MDPI journal — 15%, double the global rate. In 40 universities, MDPI was the most-used publisher, including private institutions such as the International University of La Rioja (UNIR) and the Open University of Catalonia (UOC), and the public National University of Distance Education (UNED).

Only four out of every 10 journals examined in the new analysis are free of this type of self-referential work, according to the three authors, who consider this practice “a blatant case of scientific misconduct.” The problem is concentrated in dozens of MDPI journals: Sustainability (745 special issues with more than 33% of studies authored by invited editors), International Journal of Molecular Sciences (668), Energies (639), Applied Sciences (580), Materials (489). Shu-Kun Lin’s company reportedly earned $681.6 million in 2023 from article processing fees, according to Stefanie Haustein of the University of Ottawa, Canada.

“We think Shu-Kun Lin saw a market opportunity and took it in a direct and reckless way, but the cause is more fundamental,” says Hanson. “The ‘publish or perish’ incentives are what’s producing so much waste in science.”

Geographer Pilar Paneque has directed ANECA, the guardian of Spanish universities, since 2023. A year later, the agency included repeated publications in special issues as a factor in devaluing a CV. “Evaluation and funding agencies have an undeniable responsibility, not only by penalizing these bad publishing practices, as we already do, but also by incentivizing good practices, which we unfortunately talk about less. However, our action always comes after a publication that, possibly, should not have been funded or accepted by the journal,” argues Paneque.

A spokesperson for MDPI, Jisuk Kang, from Korea, commented on the new analysis at the request of this newspaper. “We recognize that endogeny [the practice of publishing studies in a self-edited special issue] is an issue affecting the scholarly publishing industry and we take concerns around editorial independence seriously,” she stated. The spokesperson asserted that “MDPI has clear safeguards in place to manage potential conflicts of interest.” According to Kang, the publisher ensures that the number of studies authored by the guest editor does not exceed 25%, and that these works are handled by an independent member of the journal’s board. “MDPI’s strong editorial framework has supported the quality and prominence of our special issues, which accounted for 62% of MDPI’s published content in 2024 and around 55% in 2025,” she added. The special issue is the new normal, according to Gómez Barreiro, Hanson, and Crosetto.

In addition to MDPI and Frontiers, the three authors analyzed BioMed Central, the Royal Society, and Springer Nature’s Discover series, which together account for almost 40% of the journals examined, but publish only about 30 special issues considered PISS each year. “We were unable to study groups like Elsevier, Springer, Wiley, or Taylor & Francis here, but this is also clearly needed,” the three researchers acknowledge.

Frontiers has published nearly 1,600 special issues classified as PISS, but a spokesperson emphasizes that these represent only 9% of its output, compared to 5% for the Royal Society, 9% for Discover, 14% for MDPI, and 24% for BioMed Central. “This highlights our successful efforts to align with industry best practices on special issues,” says the spokesperson. The publisher, the spokesperson assures, monitors the percentage of studies authored by the guest editor to ensure it does not exceed a limit, which was previously 30% of the total and is now 25%.

Gómez Barreiro, Hanson, and Crosetto summarize their aim in one sentence: “We hope our work will help publishers identify the few bad apples that threaten the rest.”

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