## Radiations And Male Fertility - The Most Comprehensive Information

November 21, 2018

# Introduction: History and sources of microwaves

Radiation can be characterized into ionizing and non-ionizing radiations, of which the latter is differentiated in two forms: 1) extremely low frequency (ELF) or power line (60 Hz) electromagnetic fields (EMFs), and 2) radio frequency (RF) EMFs - which are produced by wireless radio waves/microwaves products.

The biological effects of microwave radiations effectively begin with the development of radar early during World War II. No harmful effects of microwaves were detected before this time and are also not in the list of general environmental problems. Prausnitz and Susskind were the first who reported the effects of microwave radiation on the testicular organ in 1962 [1]. Since early 1962, many man-made devices are now in use and the most common source for microwaves are transmission lines (50–60 Hz), computer monitors (60–90 Hz), AM radio transmissions (530–1600 KHz), FM radio transmissions (88–108 MHz), television transmissions (50–700 MHz), handphones (850 MHz-2.4 GHz), microwave ovens (2.45 GHz), laptops and Wi-Fi (2.4 GHz).

The frequencies in the range of 100 kHz to 300 GHz refer to RF and represent only a part of the electromagnetic spectrum. Figure 1 shows the sources of radiofrequency electromagnetic field (RF-EMF) exposure affecting sperm parameters. In the list of new technologies, intermediate frequency (IF) has been listed as the newest source of exposure to electromagnetic fields. This frequency range falls between the low frequency (low frequency- 0.1 Hz–1 kHz) and the radio frequency (RF) (10 MHz–300 GHz). Major sources of this range are airport security scanners and anti-theft devices operated at the exits of shops.
Fig. 1

Diagrammatic representation of the various source of RF-EMF exposure effect on the brain and testicular organ and deleterious outcome

On the other hand, radiations such as X-rays, γ-rays and α-particles are forms of ionizing radiation [2].Ionizing radiation is much more dangerous than non-ionizing radiations. Significant sources of ionizing γ-rays include natural sources such as the decay of uranium in the earth, cosmic rays, the sun and radon gas, while artificial or manmade sources include radioactive waste, X-rays from medical procedures etc.

Radiation induced cancer is triggered by chromosomal damage or genomic instability [3]. An increase in chromosomal abnormalities may be a result of exposure to radiation, which was first reported by Martin et al. [4]. The most radiosensitive organ reported is the male testis with the germinal epithelium including the spermatogonia which are more sensitive to radiation exposure than other cells [5, 6].

The effects of IR on reproduction are of growing concern as the number of people exposed to radiation via medical procedures and environmental exposures is significantly increasing. Data reviewed by Yousif et al. [7] obtained from 31 studies report an association between occupational exposures to IR and either the incidence of or mortality from testicular cancer. Similar data were obtained for non-ionizing radiation from 9 studies. Since radiations have a broad range of wavelengths, it is impossible to cover all the existing ionizing and non-ionizing radiations in a single article. Further, the available data on ionizing radiation clearly indicate its role in the development of cancers, such as testicular cancer. In contrast, much less clear information is available on non-ionizing radiation. Therefore, the focus of our review is more to explore the effects of non-ionizing radiation such as RF-EMF on male fertility. This includes frequencies used for cell phones, laptops, computers, microwave ovens and some other higher frequency range; this includes the RF-EMF-induced biological effects and potential mechanisms on the male reproductive system.

The networking of RF-EMF-assisted devices like cell phones, Wi-Fi, microwave ovens, and laptops is increasing drastically and its association with male infertility has been reported [891011]. Based on sufficient evidence, it has now been increasingly realized that RF-EMF radiation is pervading the environment and has therefore been mentioned under the terms “electro-pollution” or “electro-smog” in the list of other environmental pollutants (air, water, soil, and noise pollution) [12].

The International Agency for Research on Cancer [13, 14] classified RF in group 2B as ‘possibly carcinogenic’ to humans. The guidelines on the specific absorption rate (SAR) of mobile phones are legally limited to 2.0 W/kg by the International Commission on Non-Ionizing Radiation Protection reported [15], but still the SAR level varies from country to country. SAR is a standard unit or rate at which RF-EMF energy is imparted to an element or mass to measure the penetration of energy within human tissues.

The amount of SAR absorbed by human tissue depends on many factors such as the frequency, intensity, polarization and duration of exposure [16] and most importantly the position of devices while used. A higher radiation absorption rate could be observed while talking on phone, keeping phone near head or in pants pocket, using laptop computer on lap connected with Wi-Fi and frequently use of microwave ovens. Agarwal et al. suggested that using mobile phones adversely affects the quality of semen by decreasing the sperm count, motility, viability and morphology, which might contribute to male infertility [17]. Consequently, Desai et al. concluded that RF-EMF exposure might induce DNA damage due to increased oxidative stress, which may accelerate spermatozoal cell death and promote testicular carcinogenesis [18]. Many animal studies on the use of mobile phones are linked to a reduction in sperm count [9] and motility [19], suggesting an impairment of male fertility. Similarly, in humans, Agarwal et al. reported that the continuous use of mobile phones is associated with decreased motility, sperm concentration, morphology and viability [20]. The most significant studies on the effect of RF-EMF emitted from different sources (cell phones, microwave ovens, laptops, and Wi-Fi devices) on animal and human fertility pattern are summarized in Table 1 [2122232425262728293031323334353637].

The literature shows that studies investigating the deleterious effects of cell phone and microwave exposure on male reproductive organs are mainly concentrating on sperm parameters [9, 25, 38]. However, till date, no possible mechanisms on how RF-EMF radiation interacts with the male reproductive organs and thereby affect the fertility pattern are known. Some of the concerns are listed and discussed in detail by introducing 1) biophysics of RF-EMF radiation, 2) effect of RF-EMF on sperm parameters 3) role of kinases in cellular metabolism 4) genotoxic effect of EMF leading to genomic instability 5) RF-induced oxidative stress 6) RF-EMF effect on reproductive endocrine system, and 7) protective measures for these radiations and future recommendations.

## Biophysical parameters of RF-EMF

The biophysical parameters describe the physical and biological factors, which determine cellular radio-sensitivity of RF-EMF exposure by measuring the absorption rate of the radiation. In theory, the EMF must penetrate the exposed biological system and induce internal EMFs to cause a biological response. On the other hand, the penetration depth or RF radiation absorption depends on incident field parameters (like intensity, power density), zone of exposure, shape, geometry, and orientation of the object; and configuration of the radiation, e.g., how close is the object from the RFR source? [39]. These parameters directly or indirectly participate in free radical formation by increasing ROS levels, which have been found to be a factor for DNA damage. Kumar et al. have reported sperm DNA damage after 3G mobile phone exposures [26].

DNA damage is one of the serious concerns in respect to infertility or testicular cancer. The question, however, is how such a low frequency RF radiation may cause DNA damage? This question is not easy to answer, but it is assumed that a RF electro-magnetic field is classified as non-ionizing radiation because the photons do not have sufficient energy to break chemical bonds or directly ionize biological molecules [39]. Therefore, it is generally accepted that the EMF energy is not enough to damage DNA directly, thus indirect mechanisms, such as the free radical hypothesis, have been proposed to explain EMF-induced DNA damage [404142]. Cell phones and its transmission towers, are both equally responsible for health effects, as cell phones emit radiations to nearby relay base stations or antennas. Our bodies act as antennas that absorb the radiation and convert it into alternating eddy currents [43]. Cell phone radiation is generated in the transmitter, and is emitted through the antenna in the form of radio waves [16, 39, 44]. The impact of this RF-EMF on the human body is measured via a standardized unit called the SAR. The rate of energy absorbed by or deposited per unit mass per unit time is the SAR and E-filed can be calculated by-
$SAR\left(W/Kg\right)=\sigma {E}^{2}/\rho$

Where sigma (σ) is the conductivity of the liquid and rho (ρ) is the density of liquid. The measured E-field values and SAR distribution are 1 g and 10 g mass averaged SAR values.

When a biological body or tissue is exposed to RF-EMF, the RF energy is scattered and attenuated as it penetrates body tissues. Energy absorption is largely a function of the radiation frequency and the composition of the exposed tissue. The problem of physics in respect to EMF exposure is of penetration depth. The higher absorption rate of radiations emitting from a cell phone is more absorbed inside the tissue while making a cell phone call or using electromagnetic devices.

Testicles are very sensitive to these radiations because of the development and maturation processes of sperm taking place in the testicles. It is also well established that the developing phase of the brain and the testicles are very sensitive to radiation, which may cause severe damages in the form of genotoxic effects [9, 25, 26, 45]. Several studies suggest that microwave radiations are potentially strong enough to penetrate the brain cranium, and nearly 40% of these can reach deeper into the brain [46, 47]; penetration depths of 4–5 cm are assumed [48, 49]. The same applies to the testes.

During testicular developmental stages, the penetration depth is not the sole factor, but also i) exposure time; ii) duration of exposure (i.e. number of exposure days); iii) the greater number of undeveloped cells exposed to microwaves; and iv) the water content of the organ (the greater the amount of water in an organ, the greater will be the effect of the microwave radiation). Several studies also reported that EMF-induced morphological changes are also depending on the type, dose, mode and duration of the EMF-exposure [5051525354]. Therefore, it is imperative to explore biophysical parameters related to RF-EMF exposure and causative factors, first.

## The effect of RF-EMF exposure on sperm parameters

In light of reports indicating that in 2005 7.4% of couples in the United States were infertile [55], and that this number is predicted to increase as high as 15%, particularly in industrialized countries [56], one can link the increasing usage of RF devices such as cell phones or Wi-Fi, with RF-EMF induced sperm damages as this is closely related to infertility. Although there are numerous other factors such as sperm quality, sperm count, motility and morphology impair with increasing age, and lifestyle factors for example alcohol consumption, cigarette smoking that may affect fertility pattern in both male and female, frequent use of cell phone or EMF devices contribute markedly to this poor semen quality (Figure 1).

Apart from this, cell phone usage has been linked to decreases in progressive motile sperm count [20] motility [20] and viability [20, 34], as well as to increases in ROS [29] and abnormal sperm morphology. Recent evidence also shows that Wi-Fi from laptops negatively affects sperm quality [8]. EMF is also responsible for the decrease in fertilization rate [57], spermatogenic cell numbers and trigger apoptosis [58, 59], reduced sperm quality [60], hormonal changes in the testis [20, 61], and may give rise to fetal loss and developmental impairments in the embryonic period [45, 62] (Table 2) [9, 20, 25, 26, 2829303132, 34, 38, 63].

## Sperm count

Radio-frequency electromagnetic field exposure from cell phones or other sources of microwaves adversely affect the male fertilizing potential of spermatozoa [29]. There are several techniques available for the measurement of sperm count like hemocytometer, flow cytometry and cell counter. Using flow cytometry, Kesari et al. showed a significantly (P < 0.0001) decreased percent of sperm count (61.33 ± 3.68% vs. 31.14 ± 13.6%) and an increased percentage of apoptotic cells (5.93 ± 1.64% vs. 13.15 ± 1.26%) after cell phone exposure (2 h/day for 35 days) in an animal study [9]. In addition to cell phone radiation, the exposure of male Wistar rats to Wi-Fi connected laptop computers (EMF, 1.15 micro Tesla, μT) for 7 h/day for 1 week also reduced sperm count and motility [64]. Other studies have also linked RF-EMF [34, 37, 61, 65, 66] or cell phone radiation [676869] to deleterious effects on the testes. Such radiation exposure may create a state of oxidative stress and stimulates free radical generation by the sperm mitochondria [67].

## Sperm motility and morphology

There is also a list of studies indicating the negative influence of RF-EMF on sperm motility and morphology. Several authors found that carrying GSM phones in the trouser pocket or on the belt decreased rapid progressive motility of sperm [70, 71]. Kesari and Behari demonstrated that males who use mobile phones exhibit increased rates of abnormal sperm morphology [28]. Several groups showed that men using mobile phones have decreased sperm concentration, motility, normal morphology, and viability [16, 28, 37, 72, 73]. Further, Luo et al. [74] showed that RF-EMF exposure is directly affecting the testes by causing a significant decrease in the diameter and weight of the seminiferous tubules as well as the mean height of the germinal epithelium and pathological and physiological changes in testicular tissues, respectively, thus, giving evidence for the growing concerns of increasing incidences of infertility [17, 26].

The link between the exposure to RF-EMF and testicular pathologies and decreasing sperm quality is most probably oxidative stress by increasing levels of free radicals or superoxide anion as a decrease in sperm motility and viability is triggered by increasing concentrations of superoxide anion (O2) [34]. Free radicals oxidize membrane phospholipids extracellularly, thus causing decreased viability and reduced membrane fluidity with impaired motility.

## Role of kinases in sperm cell cycle and apoptosis

Apoptosis plays an important role in adjusting the appropriate number of proliferating germ cells associated with the surrounding Sertoli cells during spermatogenesis [75, 76]. Apoptosis or programmed cell death in the tissues of an organism is an important and inevitable event in the remodeling of tissues during development and spermatogenesis [77]. Cell cycle analysis by flow cytometer has confirmed these results because EMF exposure induces the appearance of a sub-G1 apoptotic peak, which is characteristic of DNA fragmentation in spermatozoa [30]. Cell phone radiation exposure showed a significant decrease in G0–G1 phase of sperm cell cycle (3.26% ± 1.64%: P = 0.042) and G2/M (15.11% ± 1.41%: P = 0.022) as compared to the control group (4.12% ± 0.58%) and G2/M (18.84% ± 3.05%), respectively [34]. An increased level of apoptotic sperm was detected after exposure to 2.45 GHz (14.30% ± 1.92%) and mobile phone (13.15% ± 1.25%) as compared with sham-exposed group (7.43% ± 1.30%) and (5.93% ± 1.64%), respectively [9, 31].

Spermatogenesis is an active proliferative process consisting of two phases: the mitotic and meiotic phase. The cell cycle is regulated by a control system formed by molecules that trigger and coordinate key events. These molecules act primarily at two important checkpoints in the cell cycle, G0 to G1, and G2 to M [16]. Initiation of the M-phase in the sperm cell cycle requires a protein kinase complex consisting of a catalytic subunit [78, 79] and regulatory sub-unit. Assessment of the catalytic activity of a specific protein kinase plays an important role in elucidating signal transduction pathways, which may affect cell behavior.

Kesari et al. have investigated a significant (P = 0.003) decrease in the level of sperm PKC activity after mobile phone exposure (2876 ± 617.9 P32 counts/mg protein) as compared to the control group (3013 ± 520.67 P32 counts /mg protein, where P32 is radioactive phosphorus-32 labeled ATP) [9]. Several other studies also reported a decline in sperm motility together with a decrease in PKC activity [80, 81]. This could mediate the cellular response to extracellular stimuli involved in proliferation, apoptosis, decreased sperm count, and exocytotic discharge in a number of non-neuronal cells i.e. sperm [31, 82]. Kesari et al. have reported a significant decline (P = 0.006) in sperm histone kinase activity in a microwave-exposed group (3659.08 ± 1399.40 P32 counts/mg protein) as compared to the sham-exposed one (5374.91 ± 1366.91 P32 counts/mg protein) [38]. Decrease in histone H1 kinase activity just before the entry of differentiating cells into the M-phase, suggesting a universal role of Cdc2/Cdk2 (cell division cycle/cyclin-dependent kinase) kinase to regulate the G2/M transition [34]. Kumar et al. [30] and Kesari et al. [9] demonstrated that depletion in the activity of both histone kinase and protein kinase may serve as a measure of microwave EMF’s ability to affect spermatogenesis and sperm cell cycle. Kumar et al. have also investigated a significantly increased (P < 0.001) level of sperm creatine kinase in the microwave-exposed group (0.24 ± 0.10 IU/108spermatozoa) compared to the sham group (0.04 ± 0.03 IU/108 spermatozoa) [29].

In spermatozoa, creatine kinase is localized in the mitochondria of the midpiece region [83]. Creatine phosphate serves as a donor for the re-phosphorylation of adenosine diphosphate (ADP) into ATP, which supports flagellar dynein/adenosine triphosphate and sperm quality [84]. Since differences in the creatine kinase activity reflect differences in sperm ATP concentrations and ATP/ADP ratios [84], it can be suggested that protein kinase C, histone kinase and creatine kinase play an important role in cell metabolism and spermatogenesis and any changes in sperm kinases due to RF-EMF or other factors may lead to infertility.

## RF-EMF exposure affects hormonal changes

Microwave exposure disrupts the seminiferous tubules and reduces the Leydig cell population and therefore the serum testosterone concentration in rats. Leydig cells secrete testosterone, where luteinizing hormone (LH) stimulates Leydig cells to produce testosterone and maintains their function. Testosterone is responsible for feedback control of the LH secretion at both the hypothalamus and pituitary. This pituitary hormone promotes the secretion of testosterone by the Leydig cells, which are the interstitial cells situated between the seminiferous tubules [85]. Leydig cells are among the most susceptible cells to EMW and injury to these cells may affect spermatogenesis [86]. Kumar et al. have reported a decline in the level of testosterone after 10 GHz of microwave exposure, where significant differences in exposed animals (1.4 ± 0.8 ng/ml) were found by comparing to the sham-exposed one (4.1 ± 1.4 ng/ml) [63].

Several studies reported that testosterone is essential for spermatogenesis, formation of spermatozoa, and maintenance of structural morphology and physiology of seminiferous tubules [87, 88]. Therefore, any changes in the level of testosterone will have detrimental effects on male fertility. Meo et al. reported that radiations may affect the state of polarization of the cellular membranes [33]. This may be responsible for distinct changes in testosterone synthesis and secretion. Since changes in serum testosterone levels may be associated with a possible effect on pineal melatonin secretion, mobile phones may cause a reduced melatonin production, which is reported in several studies [27, 89, 90]. Melatonin is an important factor in testosterone secretion because it exerts an antigonadotrophic effect mainly at the level of the hypothalamus and pituitary [919293].

RF-EMF exposure and Genotoxicity: Many in vitro and in vivo studies showed that EMF induced genotoxic single- and double-strand DNA breaks, micronucleus formation, chromosomal abbreviations, changes in gene expression, cell proliferation and apoptosis [252694959697]. Such changes are responsible for genomic instability and promote tumorigenic effect in cells. We explore the genotoxic effect of RF EMF on sperm parameters and possible infertility outcome as discussed below and which is also represented in Figure 2.

SOURCE: https://rbej.biomedcentral.com/articles/10.1186/s12958-018-0431-1?fbclid=IwAR0GVHdiQK7CdjLHV31TICjP3anuEYwevK2QGlCJsajRWfjr2qIwRGI0bw4