Re: Use of laptop computers connected to internet through Wi-Fi decreases human sperm motility and increases sperm DNA fragmentation

12 01 2012

To the Editor:

We read with interest the article “Use of laptop computers connected to internet through Wi-Fi decreases human sperm motility and increases sperm DNA fragmentation” by Avendano et al.(1). However, we do actually think that the evidence presented in this paper cannot support the claim that the observed effects are nonthermal and caused by exposure to a Wi-Fi radiofrequency electromagnetic field.

Keeping constant the temperature under the computer by an air conditioning system is not sufficient to ensure homogeneity of the temperatures within the experimental area, since the heat source from the laptop is not homogenous itself, and to exclude that there is no local variation in the samples temperatures.

If the exposure design can be justified by the desire of being as close as possible to the actual conditions of use of a laptop computer, the dosimetry used in these experiments is much too simplistic. There is no indication of the homogeneity of the field under the laptop, which may greatly depend upon the location of the Wi-Fi antenna within the computer.

The control samples, “kept in another room away from any computers or electronic devices”, were not actually kept under identical conditions. A more suitable experimental design would have been a sham exposure design in which control samples would have been exposed under the same actively working computer, but with its Wi-Fi emission turned off.

Moreover, Avendano et al. state that “RF-EMW from mobile phones may cause DNA damage” and that “Research has shown negative consequences of electromagnetic fields on biological mechanisms,” and cite in support to their contention a highly controversial paper (2). Genotoxicity of radiofrequencies is not a matter of opinion: radiofrequency energy absorption cannot break DNA molecules, and it should be kept in mind that there is no known biologically plausible mechanism by which nonionizing radio waves of low energy can disrupt DNA (3). Recently, while classifying RF-EMF as “possibly carcinogenic to humans” (Group 2B), the IARC Working Group reached the overall conclusion that there is only weak mechanistic evidnce relevant to RF-EMF-induced cancer in humans (4).

There is a serious message behind our rebuttal. Citing Avendano et al. (1) among the evidence of an association between Wi-Fi exposure and a genotoxic effect on human sperm would demonstrate how studies with an erroneous methodology can be used to support important public health claims and also the weakness of the evidence purporting to demonstrate a nonthermal effect of Wi-Fi RF.

Jean-François Doré, Ph.D.
Marie-Christine Chignol, E.P.H.E.
Centre de Recherche en Cancérologie de Lyon
Lyon, France

1. Avendano 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; on line . doi:10.1016/j.fertnstert.2011.10.012

2. Diem E, Schwarz C, Adlkofer F, Jahn O, Rudiger H. Non-thermal DNA breakage by mobile-phone radiation (1800 MHz) in human fibroblasts and in transformed GFSH-R17 rat granulosa cells in vitro. Mutat Res 2005;583: 178–83.

3. Moulder JE, Foster KR, Erdreich LS, McNamee JP. Mobile phones, mobile phone base stations and cancer: a review. Int J Radiat Biol. 2005;81(3):189–203.

4. Baan R, Grosse Y, Lauby-Secretan B, El Ghissassi F, Bouvard V, Benbrahim-Tallaa L, Guha N, Islami F, Galichet L, Straif ;WHO International Agency for Research on Cancer Monograph Working Group. Carcinogenicity of radiofrequency electromagnetic fields. The Lancet Oncology 2011;12:624-6.

Published online in Fertility and Sterility doi:10.1016/j.fertnstert.2012.01.102

The Authors Respond:

We thank Drs Doré and Chignol (1) for their interest and comments on our article (2). The aim of our study was to evaluate the impact of laptop computers connected to internet through Wi-Fi on human sperm. To assess this potential association we used an in vitro model incubating human sperm in the presence of an active portable computer connected to the internet by Wi-Fi. Dore and Chignol suggest that the sperm damage could have been caused by thermal effects. However, the temperature on each incubation culture medium drop was controlled by an IVF thermometer, and no changes were observed. We have discussed different possible mechanisms responsible for the detrimental effects observed. Decrease of sperm motility and increase in DNA fragmentation may be caused by non-thermal effects such as lipid peroxidation and reactive oxygen species (ROS) generation (3).

Genotoxic effects of radiofrequency have been reported in various studies (4-6). Although the energy of nonionizing electromagnetic field is not sufficient to break DNA directly, as mentioned by Doré and Chignol (1), the effects could be mediated by indirect mechanisms such as ROS production. In fact, both De Iuliis et al. (7) described sperm DNA fragmentation and motility decrease after exposure of human spermatozoa to radio-frequency electromagnetic radiation (RF-EMR) in the range of that emitted by mobile phones. These authors and Agarwal et al. (8), who also observed a decrease in sperm motility, attributed those deleterious effects to increased production of ROS.

We agree the best control to conclude that the damage was caused by Wi-Fi is the same laptop working without Wi-Fi. We performed this experiment using different samples of the same donors and preliminary data indicate no impact on DNA structure when the computer is not connected via Wi-Fi. Furthermore, we are currently performing a new study, which examines the relationship between different brands of laptop computers, connected or not to internet via Wi-Fi, and sperm quality. We believe the preliminary results presented in our published paper (2) merited being reported and that further studies are needed to confirm these findings and evaluate the mechanisms by which sperm may be affected.

We also truly believe we have been appropriately cautious in our conclusions, recommending further studies and stating possible caveats to our interpretation and experimental design. The data on the effects of RF-EMR on human sperm, however, should not be ignored.

Conrado Avendano, M.S.
Nascentis Medicina Reproductiva
Cordoba, Argentina

1. Doré JF and Chignol MC. Re: 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. Avendano 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. Higuchi Y. Chromosomal DNA fragmentation in apoptosis and necrosis induced by oxidative stress. Biochem Pharmacol 2003; 66:1527-35.

4. Garaj-Vrhovac V, Horvat D, and Koren Z. The relationship between colony-forming ability, chromosome aberrations and incidence of micronuclei in V79 Chinese hamster cells exposed to microwave radiation. Mutat Res 1991; 263:143-9.

5. Zotti-Martelli L, Peccatori M, Scarpato R, and Migliore L. Induction of micronuclei in human lymphocytes exposed in vitro to microwave radiation. Mutat Res 2000; 472:51-8.

6. Maes A, Verschaeve L, Arroyo A, De Wagter C, and Vercruyssen L. In vitro cytogenetic effects of 2450 MHz waves on human peripheral blood lymphocytes. Bioelectromagnetics 1993; 14:495-501.

7. De Iuliis GN, Newey RJ, King BV, and Aitken RJ. Mobile phone radiation induces reactive oxygen species production and DNA damage in human spermatozoa in vitro. PLoS One 2009; 4:e6446.

8. Agarwal A, Desai NR, Makker K, Varghese A, Mouradi R, Sabanegh E, and Sharma R. Effects of radiofrequency electromagnetic waves (RF-EMW) from cellular phones on human ejaculated semen: an in vitro pilot study. Fertil Steril 2009; 92:1318-25.

Published online in Fertility and Sterility doi:10.1016/j.fertnstert.2012.01.103




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