Mobile Phone Radiation Induces Reactive Oxygen Species Production and DNA Damage in Human Spermatozoa In Vitro

Abstract

BackgroundIn recent times there has been some controversy over the impact of electromagnetic radiation on human health. The significance of mobile phone radiation on male reproduction is a key element of this debate since several studies have suggested a relationship between mobile phone use and semen quality. The potential mechanisms involved have not been established, however, human spermatozoa are known to be particularly vulnerable to oxidative stress by virtue of the abundant availability of substrates for free radical attack and the lack of cytoplasmic space to accommodate antioxidant enzymes. Moreover, the induction of oxidative stress in these cells not only perturbs their capacity for fertilization but also contributes to sperm DNA damage. The latter has, in turn, been linked with poor fertility, an increased incidence of miscarriage and morbidity in the offspring, including childhood cancer. In light of these associations, we have analyzed the influence of RF-EMR on the cell biology of human spermatozoa in vitro.Principal FindingsPurified human spermatozoa were exposed to radio-frequency electromagnetic radiation (RF-EMR) tuned to 1.8 GHz and covering a range of specific absorption rates (SAR) from 0.4 W/kg to 27.5 W/kg. In step with increasing SAR, motility and vitality were significantly reduced after RF-EMR exposure, while the mitochondrial generation of reactive oxygen species and DNA fragmentation were significantly elevated (P<0.001). Furthermore, we also observed highly significant relationships between SAR, the oxidative DNA damage bio-marker, 8-OH-dG, and DNA fragmentation after RF-EMR exposure.ConclusionsRF-EMR in both the power density and frequency range of mobile phones enhances mitochondrial reactive oxygen species generation by human spermatozoa, decreasing the motility and vitality of these cells while stimulating DNA base adduct formation and, ultimately DNA fragmentation. These findings have clear implications for the safety of extensive mobile phone use by males of reproductive age, potentially affecting both their fertility and the health and wellbeing of their offspring.

Apoptosis and DNA damage in human spermatozoa

“…47 This link is causative because if mitochondrial ROS generation is artificially triggered using rotenone to stimulate free radical generation at complex I of the electron transport chain, then the spermatozoa exhibit both lipid peroxidation and a loss of motility that can be reversed by the concomitant presence of an antioxidant such as a-tocopherol. 47 The stimulation of mitochondrial ROS generation can also result in oxidative DNA damage to spermatozoa, for example, when spermatozoa are irradiated with radiofrequency electromagnetic radiation 21 or when mitochondrial ROS is triggered after exposure to unsaturated fatty acids. 48 Thus, there is a plausible role for mitochondrial ROS in the etiology of DNA damage in human spermatozoa, although the factors responsible for stimulating free radical leakage from the mitochondria are still unresolved.…”

“…52 Moreover, pre-exposure of human spermatozoa to antioxidants, such as melatonin or catalase, will prevent this apoptotic response. 53,54 Such an apoptotic cascade can also be precipitated by a variety of factors that induce oxidative stress in spermatozoa by triggering free radical generation by the mitochondria, including exposure to radiofrequency electromagnetic radiation, 21 treatment with unsaturated fatty acids 48 and dosing with the phosphatidylinositol 3-kinase inhibitor, wortmannin (Koppers AJ and Aitken RJ, unpubl. obs.…”

“…Thus, cryostorage is wellknown to be associated with the induction of DNA damage and, again, a majority of this damage seems to be oxidative. 58,59 Similarly, heat exposure will induce free radical generation by the spermatozoa as a consequence of the initiation of apoptotic cascade, and so will exposure to radiofrequency electromagnetic radiation 21 or hydrogen peroxide. 52 All of these conditions are associated with the creation of oxidative stress.…”

“…19 If the oocyte makes a mistake at this point, there is the potential to create a mutation which, because it precedes S phase of the first mitotic division, will be in every cell in the body. Through such a mechanism, DNA damage induced in spermatozoa by such factors as smoking, 20 exposure to radiofrequency electromagnetic radiation 21 or age 22 could increase the mutational load carried by the embryo, resulting in miscarriage or serious disease in the offspring, including cancer. 9,10 A corollary of this hypothesis is that the mutational load carried by the embryo will also be influenced by the DNA repair capacity of the oocyte.…”

Electromagnetic pollution: another risk factor for infertility, or a red herring?

“…de Iuliis et al In the study published by de Iuliis et al 17 in 2009, isolated and purified human sperm samples were exposed to RF-EMF at various SAR values up to 27.5 W kg 21 , well above the EMF and infertility A Lerchl 202 allowed exposure limits and clearly in the thermal range. However, some effects (lowered viability and motility, increased levels of reactive oxygen species and DNA fragmentation) occurred at levels of 1 W kg 21 , below the limits for localized exposure (Table 1).…”