Introduction

Mobile phones and their base stations transmit and receive signals using electromagnetic waves. Electromagnetic waves are emitted by many natural and man-made sources and play a very important role in our lives. Extensive epidemiological studies are commonly expected to provide the answer to whether electromagnetic field (EMF) exposure might be hazardous to people. However, findings and scientific validation of any potential health hazard, whether cancer or non-cancer effect, might be not possible using an epidemiological approach alone. Therefore, biological effects of EMF and their consequences on human health are receiving increasing scientific interest and have now become an urgent problem. It has been previously shown that Global System for Mobile Communication-like electromagnetic field (GSM-EMF) radiation can cause hematological, cardiac, endocrine, immunological, reproductive, and nervous system changes and also induce oxidative stress, cataracts, and behavioral changes in animal models (Lin 2003; Black and Heynick 2003; Koyu et al. 2005; Nittby et al. 2007; Kismali et al. 2009; Sarookhani et al. 2011; Jelodar et al. 2011; Khirazova et al. 2012; Jelodar et al. 2012). In humans, only the histological effects of using EMF radiation on the central nervous system and male genital organs were determined in a few studies (Albert et al. 1981; Tsurita et al. 2000; Salford et al. 2003).

To the best of our knowledge, there are only a few reports about the pathological changes associated with GSM-EMF radiation. Therefore, the aim of this study was to investigate whether the histological features of the heart, liver, and kidney of adult male Sprague–Dawley rats could be altered after exposure to the 900-MHz GSM-like EMF generator.

Materials and methods

Animal

Twenty male Sprague–Dawley rats, aged 12 weeks and weighing 170–190 g, were used as mature rats in this study. Animals were fed with water and standard laboratory diet available ad libitum. The study was approved by the Ethical Committee of the University of Shiraz.

Radio frequency wave generator

A signal generator for producing a 900-MHz signal was synthesized by the Department of Electronics from the Engineering College, Shiraz University, and the output was monitored by a spectrum analyzer (FSH6, made by Rohde and Schwarz, Germany) to ensure the correct forward power from the custom-designed mobile base stations for the animals exposed.

Experiment

Rats were divided randomly into four equal independent groups—5 of which were used as control (without EMF) and 15 of which, according to the time of exposure to EMF (1, 2, and 4 h), were divided into three subgroups (low, moderate, and high dose) with 5 per group. The exposures were performed for 30 consecutive days.

Histopathological evaluations

The animals were killed by cervical dislocation, and the heart, liver, and left kidney were immediately removed, free of surrounding fat, and fixed in 10 % buffered formalin for histopathologic examination. Formalin-fixed tissues were processed routinely and embedded in paraffin. Blocks were cut at 5 μm, and sections were stained with hematoxylin–eosin and studied microscopically.

Results

No toxic or behavioral changes were seen in any rats. Postmortem examination revealed focal lesions in the kidneys. Histopathologic examination of the hearts showed subendocardial hemorrhage in four rats, one rat from each group (Fig. 1). In the kidney, interstitial inflammation, hemorrhage, and congestion in the glomeruli and vessels were seen in all cases (Fig. 2). No significant histopathological lesions were observed in the liver. These pathological lesions were seen in all four experimental groups and were not EMF-specific changes.

Fig. 1
figure 1

Subendocardial hemorrhage of the heart of rats in four groups. Black arrows indicate the exact place of lesions (H&E, ×400)

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Fig. 2
figure 2

Pathological changes of the kidney in four groups. a Congested glomeruli and vessels. b Interstitial inflammation and congestion. Black arrows indicate the exact place of lesions (H&E, ×400)

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Discussion

In the present study, pathological effects of a 900-MHz GSM-like EMF radiation emitted from a mobile phone simulator were evaluated by determining the existence of pathological lesions in the heart, liver, and kidney. Our results showed that some pathological lesions include inflammation, hemorrhage, and congestion, especially in the kidney among these three vital organs (Figs. 1 and 2). Investigations that evaluated the EMF radiation-related pathological changes are scarce and mainly focused on nervous system changes. Albert and his colleagues studied the effects of either 0.1 or 2.45 GHz, applied to young rats, on the histological appearance of cerebellar Purkinje cells. Exposure to both frequencies had similar effects, producing irreversible decreases of Purkinje cells in rats irradiated (Albert et al. 1981). Tsurita et al. (2000) investigated the effects of exposure to 1.439-GHz time division multiple access (TDMA) signals on Purkinje cells in the cerebellum of rats. No morphological changes were observed in any groups (Tsurita et al. 2000). The different results obtained by Albert et al. (1981) and Tsurita et al. (2000) might be due to the very different ages of the rats used. In another study conducted by Salford et al. (2003), nerve cell damage in the mammalian brain after exposure to microwaves from GSM mobile phones was evaluated. They found significant evidence for neuronal damage in the cortex, hippocampus, and basal ganglia in the brains of exposed rats (Salford et al. 2003). Our results are in agreement with the results of the previous research conducted by Forgács et al. (2006). They evaluated the effects of whole-body 1,800-MHz GSM-like microwave exposure on testicular steroidogenesis and histology in mice. In their study, the lack of any microwave-related histopathological alterations in the investigated organs including the testes, epididymes, adrenals, prostates, kidneys, hearts, liver, and pituitary was reported.

Further investigations are required to establish the biological and pathological significance of using the GSM-like EMF radiation. Also, other results must be focused on identifying the mechanism of possible effects of radiation.