Commentary: Sperm Counts, Data Responsibility, and Good Scientific Practice

Skakkebaek, Niels E.; Andersson, Anna-Maria; Juul, Anders; Jensen, Tina Kold; Almstrup, Kristian; Toppari, Jorma; Jørgensen, Niels

doi: 10.1097/EDE.0b013e318229ec01
Sperm Counts
Author Information

From the University Department of Growth and Reproduction, Rigshospitalet, Copenhagen, Denmark.

Correspondence: Niels E. Skakkebaek, University Department of Growth and Reproduction, Rigshospitalet, Section GR5064, 9 Blegdamsvej, DK-2100 Copenhagen, Denmark. E-mail:

Article Outline

Is it good scientific practice to publish other researchers' data without permission before these data have appeared in a peer-reviewed scientific journal? Is it good scientific practice to cite newspapers as a source of truth in scientific articles or to claim that other researchers have withheld data—without providing any kind of evidence for such a claim? Is it good practice for an editor of a scientific journal, in collaboration with an invited scientist, to publish editorials that contain serious and misleading accusations against another group of scientists without giving that group a chance to tell their side of the story?

Most people would probably say “no” to these questions. Nevertheless, after 2 articles about our ongoing research by Jens Peter Bonde, Cecilia Høst Ramlau-Hansen, and Jørn Olsen1 and by Allen Wilcox,2 were published online in Epidemiology, we feel a need to pose the questions. Only a couple of days before the papers appeared online, we learned from Jens Peter Bonde that he and Jørn Olsen intended to publish a commentary about our (scientifically unpublished) data, followed by an editorial by the editor of the journal, Allen Wilcox. Although we immediately asked them to stop the process, they declined to do so. Furthermore, the facts of the story are quite different from those reported in the 2 papers.

Wilcox terms us “scientists who collected” the data and indicates that the data belong to the public. However, the data in the figure reported by Bonde et al1 were not just collected (as can sometimes be done in epidemiologic studies). The data were generated through systematic and laborious research projects conducted over many years, involving meticulous work by many clinicians, including many PhD students. Each volunteer had a clinical appointment, during which a medical history was taken, a physical examination was performed, and blood and urine samples were collected, before a comprehensive semen analysis was done in our laboratory. The project was funded from various international sources (European Union) and national sources (the Danish Environmental Protection Agency, private foundations, the National Hospital Research Fund, the University of Copenhagen, and the Danish Agency for Science, Technology, and Innovation).

In recent years, the project has received additional financial support from the Danish National Board of Health, and we supplied the Board with internal reports on the results with expectation of confidentiality. However, without giving us any prior warning, the Board posted our results on their Web site in early April. When we learned of this, we asked for the data to be removed from the Web site until the results had been appropriately published in a scientific journal following the standard peer-review process. The Board declined to do so.

When the commentary and editorial appeared in Epidemiology, we were even more surprised to see that not only did the authors use our unpublished data, but they also justified their use of our data by accusing us of withholding the data. This accusation is, however, not in accordance with the truth.

In 2008, we tried to publish an article containing a figure similar to the one Bonde et al1 have now included in their commentary, showing stable sperm counts in Denmark, contrasting with a downward trend in sperm counts in Finland. However, our paper was rejected by 2 leading journals in the field. One referee said frankly: “most results reported in this new article are not very original and are confirming previous data.” As part of the Danish material had been published before,3,4 we cut the Danish data out of the manuscript and the Finnish data were subsequently published separately.5 But now Bonde et al and Wilcox are attacking our scientific integrity by raising suspicions that we have disingenuously published the decreasing Finnish trend, and have withheld the data showing the unchanged Danish sperm count. Obviously, we have an interest in and obligation to publish our data on continuing low sperm counts in Denmark, which is consistent with our recent report of unchanged (but high) incidence of testicular cancer in Denmark in the same time period.6 We believe these findings are relevant to the sperm count data, as testis cancer is associated with risk of poor semen quality.

Finally, is it logical to conclude that unchanged disease trends during the past 10–15 years contradict reports of increasing reproductive problems during the previous 50 years? No, of course not. Despite stabilized testis cancer rates, Denmark still has one of the highest rates of testicular cancer in the world.7 Similarly, the stabilization of sperm counts at a low level does not mean that the underlying problem has ceased to exist. Unfortunately, high rates of other reproductive problems have also recently been reported in Denmark, including cryptorchidism8 and hypospadias.9

In conclusion, we believe that the rule that scientists have the right to be the first to publish their own research has been clearly broken. Wilcox had no basis, except false rumors, to believe that we would not publish. As editor, Wilcox bypassed the normal peer-review system by inviting competing Danish scientists to publish a comment on our raw data in his journal. This can hardly be in the interest of any society. It runs counter to several fundamental principles of the scientific peer-review process, namely publication of data that has not been subjected to this process, and, equally, that all of those contributing to the project (the authors) have to approve submission of the data. These principles are in place to guarantee the quality and legitimacy of the data and to guard against scientific fraud. We subscribe wholeheartedly to these principles, even if others appear to flout them.

Back to Top | Article Outline


1.Bonde JP, RamlauHansen CH, Olsen J. Trends in sperm counts: the saga continues. Epidemiology. 2011;22:617–619.
2.Wilcox AJ. On Sperm counts and data responsibility. Epidemiology. 2011;22:615–616.
3.Andersen AG, Jensen TK, Carlsen E, et al. High frequency of sub-optimal semen quality in an unselected population of young men. Human Reproduction. 2000;15:366–372.
4.Jorgensen N, Carlsen E, Nermoen I, et al. East-West gradient in semen quality in the Nordic-Baltic area: a study of men from the general population in Denmark, Norway, Estonia and Finland. Human Reproduction. 2002;17:2199–2208.
5.Jorgensen N, Vierula M, Jacobsen R, et al. Recent adverse trends in semen quality and testis cancer incidence among Finnish men. Int J Androl. In press.
6.Schmiedel S, Schuz J, Skakkebaek NE, Johansen C. Testicular germ cell cancer incidence in an immigration perspective, Denmark, 1978 to 2003. J Urol. 2010;183:1378–1382.
7.Chia V, Quraishi S, Devesa S, Purdue M, Cook M, McGlynn K. International trends in the incidence of testicular cancer, 1973–2002. Cancer Epidemiol Biomarkers Prev. 2010;19:1151–1159.
8.Boisen KA, Kaleva M, Main KM, et al. Difference in prevalence of congenital cryptorchidism in infants between two Nordic countries. Lancet. 2004;363:1264–1269.
9.Boisen KA, Chellakooty M, Schmidt IM, et al. Hypospadias in a cohort of 1072 Danish newborn boys: prevalence and relationship to placental weight, anthropometrical measurements at birth, and reproductive hormone levels at three months of age. J Clin Endocrinol Metab. 2005;90:4041–4046.
© 2011 Lippincott Williams & Wilkins, Inc.