Effect of mobile frequencies exposure on histology of retina and cornea in pregnant albino mice

R.N. Al-Shammary¹, Z.D. Mohammed Zaki ² and A.G. Alhaaik³

¹Department of Physics, College of Education for Pure Science, University of Mosul, ²Department of Dentistry, Al-Noor University College, ³Department of Anatomy, College of Veterinary Medicine, University of Mosul, Mosul, Iraq

rawahnaji@uomosul.edu.iq,https://orcid.org/0000-0003-1676-7217

zeena.dabian@alnoor.edu.iq, https://orcid.org/0000-0001-8901-6444

alhaaik_ag@uomosul.edu.iq, https://orcid.org/0000-0002-1473-7631

Abstract

In the current study, the potential effects of the Nokia mobile device were studied with frequency 900-1800 Mhz on the eyes of pregnant and non-pregnant female Swiss mice. The mice were divided into three groups: The first group is a control group consisting of five mice, the second group consists of 10 mice and the third group consists of 10 pregnant mice. Female mice of the second and third groups were exposed for a 3 hour / day and for a 30 days to a mobile device. After the end of 30 days, mice were euthanized and tissue samples were taken from the eyes of pregnant and non-pregnant mice. Microscopic examination showed, that there are significant effects on the cornea and retina of the eye, especially in pregnant females, which supports the current studies conducted on the effect of mobile phones on the eyes represented by vascularization where some sections showed newly formed blood vessels in stroma layer just beneath bowman's membrane and retina degeneration. This study concluded that the exposure to the mobile radiation led to serious histological changes in the tissues of eye which may lead to blindness.

Keywords: Mobile Phone Radiation, Retina, Cornea, Histological Effects

تأثیر التعرض لترددات للهاتف النقال على أنسجة شبکیة العین والقرنیة فی الفئران البیضاء الحامل

روعة ناجی الشمری¹، زینة ضبیان محمد زکی² و عمار غانم الحائک³

¹قسم الفیزیاء، کلیة التربیة للعلوم الصرفة، جامعة الموصل، ²قسم طب الأسنان، کلیة النور الجامعة، ³فرع التشریح، کلیة الطب البیطری، جامعة الموصل، العراق

الخلاصة

فی هذا البحث، تمت دراسة التأثیرات المحتملة لجهاز الهاتف النقال نوکیا بتردد 900- 1800 میجاهرتز على عیون إناث الفئران السویسریة. تم تقسیم الفئران إلى ثلاث مجموعات: المجموعة الأولى عبارة عن مجموعة ضابطة مکونة من خمسة فئران، والمجموعة الثانیة تتکون من 10 فئران والمجموعة الثالثة الفئران الحوامل وتتکون أیضًا من 10 فئران. تم تعریض إناث الفئران من المجموعتین الثانیة والثالثة إلى جهاز محمول لمدة 3 ساعات / یوم ولمدة شهر کامل. بعد انتهاء 30 یوماً، تم تشریح الفئران وأخذ أقسام الأنسجة من عیون الفئران الحوامل وغیر الحوامل. وبعد فحص العینات مجهریًا، تبین أن هناک تأثیرات معنویة على القرنیة وشبکیة العین خاصة عند الإناث الحوامل والتی تمثلت بضهور أوعیة دمویة فی قرنیة العین إضافة إلى تنکس خلایا الشبکیة وخلصت هذه الدراسة إلى أن التعرض للإشعاع المتنقل أدى إلى تغیرات نسیجیة خطیرة فی أنسجة العین مما قد یؤدی إلى الإصابة بالعمى.

Introduction

The excessive use of communication devices has led to the appearance of many important studies on the potential health effects of these devices on the human body (1). It has been found that many modern devices such as mobile phones, radars, and radio and television transmitters emit electromagnetic radiation (2). The mobile phone system was previously an analog system with frequency 450-900 MHz, but now, after recent development, the digital system is used at a frequency higher than 1800-1900 MHz. As a result of the emergence of health effects resulting from exposure to these rays emitted from mobile phones, many studies were conducted on this topic (2). Due to of eye sensitivity to this type of radiation, many studies had shown the presence of potential complications after direct irradiation, especially the case of cataract generation (3). It was also found that exposure of the body to microwaves leads to an increase in the temperature inside the living tissues as a result of the thermal effect of radiation (4). Others found in their study on chicken embryos that the electromagnetic waves emitted from the mobile phone caused derangement in the retinal differentiation of these embryos (5). Mobile phone may cause blurring of vision, inflammation, secretion and lacrimation of the eyes, they observed also that mobile phone cause derangement of retinal differentiation in animal (6). In addition, using of mobile phones caused blurring of vision, redness of the eyes, vision disturbance, secretion of the eyes and inflammation in the eyes of mobile phone users women or men (7). Nassar et al (8) found that 900- 1800 MHz non-ionizing radiation of the mobile phone has a marked degenerative effect on the retina of developing albino mice at the ultra-structural level, they added that all the retinal layers exhibited a reduction in their height and cell population. In the same manner, 900 MHz mobile phone like RF radiation caused noticeable differences between photoreceptors of retina of the control and exposed mice as bleaching of photoreceptors in the exposed mice (9). Current study aimed to focus on the effect of mobile phone radiation on the histological architecture of retina and cornea in pregnant and non-pregnant female mice.

Materials and methods

Animals and experimental design

In this study, 25 adult Swiss female mice were used to achieve comparison between control group and pregnant and non-pregnant mice. The mice were placed under conditions of temperature 20-25ºC and 12 hours of darkness, 12 hours of light (10). The mice divided into three groups. The first group includes five females, set as control group without exposure to radiation, the second group included 10 non pregnant females, and the third group also included 10 pregnant females. The second and third groups were exposed to radio frequencies from the mobile device for 30 days, 3 continuous hours per day. All aggregates are placed in specially designed plastic cages to allow for good ventilation and free movement.

The exposure setup

Animals were exposed using mobile phone radiation (Nokia, model 1280, MPN HKCRN1280BK, China) at a specific absorption rate (SAR) of 0.78 W / kg and frequencies from 900 to 1800 MHz at a density of 500μW / cm 2. The two devices were installed approximately 10 cm above the cage by means of a stand Railing. Exposure was continued daily (3 hours / day) and the two cell phones were set to dialing mode in order to send and receive waves during communication (11).

Histological techniques

The eyes were harvested from each group, and processed for light microscope examination by using routine histological processing method (12). Specimens of eye were fixed in Davidson’s Fluid for 24 hrs. then transferred to 10% neutral buffered formalin solution for 48hrs. The specimens then processed to prepare 5 μm thick paraffin sections and stained with Harris Hematoxylin and Eosin (13). Quantitative analysis was performed in the stained sections; the thickness of retina and cornea was measured/µm by using OMAX 5.0MP Digital USB Microscope Camera with advanced picture analysis software (ToupView). The software of camera was calibrated to the lenses of Olympus-CX31 Microscope by aid of 0.01 mm calibrating slide (ESM-11 / Japan) (14).

Results

Histological sections of cornea of control group showing the normal histological structure of corneal layers which composed from: anterior epithelium, anterior limiting membrane, stroma, posterior limiting membrane and the posterior epithelium (Figure 1A). Histological section of retina of control group showing the normal histological structure of retinal layers which included: photoreceptor cells (rod and cones), outer nuclear layer, outer plexiform layer, inner nuclear layer, inner plexiform layer and ganglionic cell layer (Figure 1B).

The histological investigation of cornea in exposed pregnant female mice (group 2) revealed a variable degrees of corneal histological changes represented by vascularization where some sections showed newly formed blood vessels in stroma layer just beneath bowman's membrane (Figure 2). Whereas in other sections there was congested blood vessels in the stromal layer with degenerated collagen fibers (Figures 3 and 4). The anterior corneal epithelium showed thickening on the tear film of squamous cell layer, in addition, the based cells and polygene cells of anterior epithelium showed signs of pyknotic nuclei (Figure 3).

The retina of female mice (group 3) exposed to the mobile radiation showed different histopathological changes represented by vacuolar degeneration of photoreceptor cells (rods and cons) especially in the outer segment of this layer (Figure 5). The exposed group 3 showed disorganization and vacuolar degeneration and necrosis in the outer nuclear layer was seen in the retina of females subjected to mobile radiation (Figure 6). Other sections of the exposed pregnant female mice showing necrosis and complete disappearance or depletion of photoreceptor cells (rods and cones) in the retina (Figures 7 and 8).

Figure 1: (A) histological section of corneal of normal control group shows the layers of cornea. (B) histological section of retina of normal control group shows the different layers of retina: 1- rods and cons, 2- outer nuclear layer, 3- outer plexiform layer, 4-inner nuclear layer, 5- inner plexiform layer, 6- ganglionic layer (HE 400X).

Figure 2: Histological section of cornea of group 2. Note the newly formed blood vessels in the stroma beneath anterior epithelium (arrows) (HE 400X).

Figure 3: Histological sections of cornea of treated group 2 shows, (A) congested blood vessel, (B) edema among collagen fibers, (red arrow) thick of tear film of anterior epithelium, (block outer) pyknotic nuclei (HE 400X).

Figure 4: Histological sections of cornea of treated group 3 showedcongested blood vessels (arrow) and (A) edema (HE 400X).

Figure 5: Histological sections of retina of exposed group 3, shows obvious vacuolar degeneration in the layer of roods and cons (A) (HE 400X).

Figure 6: Histological sections of retina of exposed group 3, shows obvious vacuolar degeneration in the layer of roods and cons (A), disorganization and degeneration of outer nuclear layer (B) (HE 400X).

Figure 7: Histological section of retina of exposed female group 2, note the complete disappearance of photoreceptor cells (A) necrotic focci in outer nuclear layer (B). (HE 400X).

Figure 8: Histological section of retina of exposed female group 2, note the complete disappearance of photoreceptor cells (A) necrotic focci in outer nuclear layer (B). (HE 400X).

Discussion

The current study describes the histological changes of radiation-induced corneal and retinal damage to the mice eye. When exposed to radio waves of a mobile device, there are two types of effects (thermal and non-thermal) (4). In the case of the eye, it is likely to be exposed to direct damage due to its limited blood supply (6), in addition to that, it is not protected by the skull as is the case for the brain. Since the retina is very sensitive, it may be exposed directly to radio radiation due to the polar characteristic of the photoreceptor cells as well as to its high water content (15).

Several studies have shown that there is a relationship between damage to the retina of the eye and exposure to electromagnetic radiation which is consistent with our current study (16). It has been found that there is a serious health effect on the plasma protein and the eyes of newborn mice as a result of exposure to radio frequencies at 900-1800 MHz emitted from mobile phones (6). The results showed that there are many pathological changes in the eye mainly represented by degenerated, hemorrhagic areas and detachment in some layers of the eye with alteration in collagen, most eye layers of the exposed group showed reduced staining affinity of polysaccharides especially in the photoreceptors(17).

Khalil (9) found that exposure to radiofrequency radiation frequency at 900 MHz for a month at a rate of 30 minutes/day caused clear differences in the photoreceptors of the retina between the control and exposed group 2 and 3 to radiation such as bleaching photoreceptors. Besides, that the retinal and corneal injury due to radiation included in dog retinal degeneration, vasculopathy and arteriosclerosis were recognized histologically and became more severe with time progress (18). In human, similar results have been proved to have different latency times ranging from 1-3 years with advanced deterioration and slight regeneration (19,20).

Conclusion

This study concluded that the exposure to the mobile radiation led to serious histological changes in the tissues of eye which may lead to blindness represented by vascularization where some sections showed newly formed blood vessels in stroma layer just beneath bowman's membrane and retina degeneration.

Acknowledgements

The authors are grateful to the College of Veterinary Medicine, University of Mosul, for the assistance and cooperation.

Conflict of interest

Authors declared that there is no conflict of interests.