To the Editor:
We read with great interest the article by Avendaño et al (1), “Use of laptop computers connected to internet through Wi-Fi decreases human sperm motility and increases sperm DNA fragmentation.” We want to congratulate the authors for their original and interesting work. However, this study has also raised a few questions.
First of all, the issue of sperm analysis method should be addressed. Indeed, sperm analysis was performed manually before selection, after swim up, and after 4 hours of incubation under the computer or not (control group). Despite efforts towards improvement and standardization of laboratory procedures (2), manual sperm analysis still suffers from a lack of precision and accuracy (3), particularly when counting progressive motile spermatozoa in an enriched supernatant. Moreover, sperm analysis was conducted here by a single observer and apparently not repeated, which leads to a high risk of intra observer variability. We also would like the authors to precise if the study was operator-blinded or if the operator was aware of the origin of the samples he was assessing. All these limitations could constitute a bias and prevent from relevant interpretation of the results. Could the authors consider automated sperm analysis as a reliable alternative in order to improve reproducibility and precision of their results? (4) Moreover, CASA could bring new insights into a potential WiFi-induced sperm motility alteration and kinetics modification.
Secondly, the authors report a significant decrease in progressive motile proportion in samples exposed to WiFi electromagnetic waves, and conclude that this may result in decreased male fertility. Although statistically significant, we do not think that the 10% decrease in progressive motile proportion observed in vitro is of biological significance and can be extrapolated in vivo. Moreover, a time-dependant or dose-dependant effect was not tested. One could postulate that WiFi-generated of sperm motility alteration and/or sperm DNA fragmentation should be correlated with the length and dose of microwaves, which should not be hard to test for experimentally. Could the authors discuss this point?
Thirdly, the authors report that semen samples with more than 0.5 million/mL of peroxidase-positive leukocytes were discarded. Did this occur in the study? Why was this threshold chosen? Furthermore, three semen samples presented isolated teratospermia. Were they included in the study? Did they behave differently when exposed to microwaves compared with normozoospermic samples?
Finally, no information is given on donors, except mean age. Did they already conceive spontaneously? Did they have professional exposure to toxicants and/or high temperature? Did they have any medical history that could impair in some way their fertility? As the authors stated in the introduction, some environmental factors have been shown to participate in the decline of male fertility. Among them, tobacco has been largely described as a cofactor of male infertility, particularly through increased oxidative stress in sperm (5). Could the authors give more information on donors included in this study, and particularly on smoking status?
Thomas Freour, Pharm.D., M.Sc.
Paul Barriere, M.D., Ph.D.
Service de Médecine et Biologie de la Reproduction
Hôpital Mère et Enfant
Nantes Cedex, France
1. Avendaño C, Mata A, Sanchez Sarmiento CA, Doncel GF. Use of laptop computers connected to internet through Wi-Fi decreases human sperm motility and increases sperm DNA fragmentation. Fertil Steril. 2012;97:39-45.
2. Cooper TG, Noonan E, von Eckardstein S, Auger J, Baker HW, Behre HM, et al. World Health Organization reference values for human semen characteristics. Hum Reprod Update. 2010;16:231-45.
3. Castilla JA, Alvarez C, Aguilar J, González-Varea C, Gonzalvo MC, Martínez L. Influence of analytical and biological variation on the clinical interpretation of seminal parameters. Hum Reprod. 2006;21:847-51.
4. Agarwal, A. and R.K. Sharma. Automation is the key to standardized semen analysis using the automated SQA-V sperm quality analyzer. Fertil Steril. 2007;87:156-62.
5. Saleh RA, Agarwal A, Sharma RK, Nelson DR, Thomas AJ Jr. Effect of cigarette smoking on levels of seminal oxidative stress in infertile men: a prospective study. Fertil Steril. 2002;78:491-9.
Published online in Fertility and Sterility doi:10.1016/j.fertnstert.2012.02.004
The Authors Respond:
We thank Drs Freour and Barriere (1) for their interest and comments on our article (2). Sperm motility was performed according WHO specification (3). Briefly, 200 spermatozoa of at least five fields were counted and scored. Each sample was analyzed on duplicate droplets, and the results were averaged. The acceptability was determinate by the difference between each replicate according WHO guidelines. Investigators assessing semen parameters and sperm DNA fragmentation were blinded to the procedure. We agree the use of computer-aided sperm analysis could bring new information about sperm kinetics and it should be considered for future studies.
Progressive sperm motility was decreased after 4 hours of incubation under a laptop connected via Wi-Fi. On the other hand, sperm DNA fragmentations was significantly increased after exposure. We speculate that both detrimental effects cumulatively may result in decreased male fertility. It has been shown that pregnancy rate increases significantly with the percentage of motile sperm (4,5) Currently, the lower limit for WHO normal values for human semen motility is 32 %. Therefore, a 10% decrease in motility in a patient with 35% of progressive motility might be clinically relevant (3).
The distance and time were chosen to maximize the likelihood of observing deleterious effects (6). According the physical law of inverse-square, the power density is inversely proportional to the square of the distance from the source of that physical power. New experiments are being conducted to see at what distance the effects disappear.
The WHO recommends a reference range for peroxidase-positive cells in semen of 1.0 millon/mL (3). Associations between leukocyte contamination, reactive oxygen species generation, lipid peroxidation and impaired sperm motility were reported (7). In order to reduce external oxidative stress, samples with more than 0.5 millon/mL of peroxidase-positive leukocytes were not included in this study.
All donors had a normal physical examination, testes with normal volume and absence of varicocele. However, we do not have information about pregnancy history. None of the donors had professional exposure to toxicants or high temperature. There was no relationship between semen parameters and the detrimental effects after exposure under the laptop. We did not inquire about smoking status; however, even if smoking had an effect, it should not be different in exposed to WiFi versus control samples.
Finally, we believe that all the issues pointed by Freour and Barrier are important and should be considered in future studies.
Conrado Avendaño, M.S.
Nascentis Medicina Reproductiva
1. Freour T and Barriere P. Use of laptop computers connected to internet through Wi-Fi decreases human sperm motility and increases sperm DNA fragmentation. (Letter to the Editor). Fertil Steril 2012.
2. Avendaño C, Mata A, Sanchez Sarmiento CA, and Doncel GF. Use of laptop computers connected to internet through Wi-Fi decreases human sperm motility and increases sperm DNA fragmentation. Fertil Steril 2012; 97:39-45 e2.
3. WHO. WHO laboratory manual for the Examination and pocessing of human semen. 5th edition ed. 2010.
4. Badawy A, Elnashar A, and Eltotongy M. Effect of sperm morphology and number on success of intrauterine insemination. Fertil Steril 2009; 91:777-81.
5. Jouannet P, Ducot B, Feneux D, and Spira A. Male factors and the likelihood of pregnancy in infertile couples. I. Study of sperm characteristics. Int J Androl 1988; 11:379-94.
6. WHO, WHO research agenda for radio frequency fields. Available at: http://www.who.int/peh-emf/research/rf_research_agenda. 2006.
7. Aitken RJ and Baker HW. Seminal leukocytes: passengers, terrorists or good samaritans? Hum Reprod 1995; 10:1736-9.
Published online in Fertility and Sterility doi:10.1016/j.fertnstert.2012.02.006