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Danish Sperm Counts Spark Data Dispute

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Science  17 Jun 2011:
Vol. 332, Issue 6036, pp. 1369-1370
DOI: 10.1126/science.332.6036.1369

A scientific scuffle over the sperm counts of Danish men has highlighted a tricky question: To whom do data belong?

A controversial study published in 1992 suggested that sperm counts worldwide had decreased by nearly half between 1938 and 1990 while testicular cancer and abnormalities had increased. That helped spark speculation that environmental pollution was wreaking havoc on male fertility. Since then, scientists have struggled to come up with data of the quality needed to resolve the contentious issue.

Last week, in what its editor acknowledges was an unusual move, the journal Epidemiology published a commentary and an editorial on new sperm count data that had not been submitted to it, nor had they been published elsewhere by the researchers who collected them. The data in question consist of sperm concentrations for 18-year-old Danish military draftees from 1996 to 2010. Although not directly contradicting the 1992 study, they reveal that there's been no significant change in Danish sperm counts during this recent 15-year period.

How did a graph of these data end up in Epidemiology? The results were originally published on the Web site of the Danish National Board of Health, which helped to fund the ongoing study. The research is being conducted by a collaboration that includes endocrinologist Niels Skakkebaek of Rigshospitalet in Copenhagen, the senior author on the 1992 sperm count study. The Board of Health's report, dated 25 March, concludes that there is no strong evidence that Danes' fertility is declining, nor that it is significantly worse than that of neighboring countries.

The editor of Epidemiology, Allen Wilcox, says he heard about the online document from an offhand remark by a young researcher originally from Denmark. “I had no idea of the background of how these landed on the Web site, but in a research world where we have such poor data on semen quality, even these raw data are useful,” he says. “My main purpose was to put the data in a better context than they were sitting on this Web site, with the report only in Danish.”

After inviting two Danish reproductive epidemiologists to write a commentary on the data, Wilcox says, he also became aware of Danish newspaper reports that the group that had collected the data had asked the Board of Health to remove the report from its Web site. One of the articles stated that Niels Jørgensen, an andrologist at Rigshospitalet and one of the leaders of the study, had said his team wanted to be very sure that the data constituted a real trend, which is only possible with 20 years of data. “That underscored my decision to publish the commentary,” Wilcox says. “He had essentially declared he had no immediate intent to do anything with the data.” Indeed, in his editorial titled “On Sperm Counts and Data Responsibility,” Wilcox not so subtly criticizes the Danish team with broad remarks such as “neither is it acceptable for valuable data to be held in storage.”

Going public.

This commentary in Epidemiology presented a research group's data on sperm counts that had been posted without the group's knowledge on a government Web site.


Skakkebaek counters that the newspaper article misquoted Jørgensen. He says Wilcox could have learned that if the editor had contacted his group before Epidemiology published the commentary and editorial. Skakkebaek further rejects insinuations that he and his colleagues have been reluctant to publish their data. He points out that in 2008 the researchers had submitted a paper, including the data that the Board of Health published, to two journals but that both rejected it. Skakkebaek forwarded the rejection letters with the referees' comments to Science. One states, in part, “most results reported in this new article are not very original and are confirming previous data.”

Skakkebaek says his group had no warning that the Board of Health was preparing or posting its report. They had submitted the data as part of a routine progress report, “on the assumption that it would be confidential,” he says. Skakkebaek says he was traveling in Paris on 12 April when the first newspaper article about the report was published. He heard about it via a phone call from his wife, he says.

Peter Saugmann-Jensen, a senior medical officer at the Board of Health who oversaw the report, says that in retrospect, the situation “could have been handled more elegantly.” But he explains that the board had decided that the data conveyed an important public health message. “You have a surveillance program for men's semen quality. It has received large amounts of public funding for more than a decade, and it has been carried out in a public hospital. We fully respect the scientists' legitimate interests, but the purely descriptive statistics concerning sperm counts are public health data that belong in the public domain.”

Widespread worry about the fertility of Danish men is another reason the board felt justified in its actions, according to Saugmann-Jensen. “We had concerns about a negative stamp being put on a whole generation of men,” he says, pointing to an article from last year with the title “The Little Princes of Denmark. Why do Danes have smaller nuts than Finns—are toxins to blame?” The board “felt there was a mismatch between the public perception that there is an ongoing deterioration in young men's reproductive potential and the fact that no change in sperm numbers had occurred over many years of state-of-the-art surveillance,” he says.

The report specifically addresses the media's role in reporting scientific findings on the topic, urging reporters and the public to remember that “statements from researchers or research groups are usually not synonymous with scientific finality.” Saugmann-Jensen says the agency did not deliberately court media attention for the report, however. He says a journalist who had heard about the report contacted him, and he was happy to answer questions.

Skakkebaek says he and Jørgensen did ask the Board of Health to remove the online report, in part because they disagree with the conclusions drawn from their data. They concur there is no decrease in sperm count over the 15-year period, but they say that the overall levels are worryingly low. The Board of Health's report plays down that concern, saying it is impossible to draw clear conclusions about what a “low” sperm count is. Danish sperm counts are similar to those observed in German and Norwegian men, it notes.

The authors of the Epidemiology commentary commissioned by Wilcox, who call the data “the best longitudinal semen data yet available,” share some of Jørgensen and Skakkebaek's concern. “The proportion of young men with low sperm counts is surprisingly large,” they write. “It is somehow hard to think it has always been so.” They conclude that further examination of possible causes—whether environmental exposures, obesity, or exposure to drugs—is warranted.

“Everyone would agree that a large proportion of these men have a low sperm count compared to the best you can have,” says Jens Peter Bonde, a professor of environmental medicine at Copenhagen University Hospital of Bispebjerg, one of the authors of the commentary. How significant that is for fertility and overall health is not yet clear, he says.

Wilcox says the fracas highlights changing ideas about who owns scientific data. “Is it the people who collect it? The people who pay for it? We are moving as a society toward the idea of data not being the property of the people who collect it,” he argues. “The researchers have temporary custody during which they can write papers, but ultimately [the data] should be in the public domain.”

When told by Science that Jørgensen, Skakkebaek, and their colleagues had submitted their data for publication and the paper had been rejected, Wilcox expressed surprise. But he says that doesn't invalidate his editorial or his decision to publish the commentary: “Then what is lost by the graph [of sperm counts] appearing on the Danish Web site? The appearance of these data simply creates more interest in and more demand for the full story.”

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