Impact of Laboratory 5G NR Base Station RF Electromagnetic Field Exposure on Physiological Parameters and Cognitive Abilities of Male Wistar Rats Across Different Age Groups

Despite the fact that 5G base stations use RF radiation parameters that comply with ICNIRP standards, public concerns about the long-term safety of exposure remain. For experimental animals, body weight is an important indicator reflecting health, development, stress, and pain, while organ weight is one of the most sensitive indicators for assessing toxicity. However, there is still relatively little in-depth research on changes in body weight.

In May 2024, a research team from Tomsk State University in Russia published an article in the journal Scientific Reports titled “The effect of exposure to RF‑EMF from the laboratory simulator of 5G NR base station on physiological parameters and cognitive abilities of male Wistar rats of different ages.” The study assessed the impact of long-term exposure to RF electromagnetic fields (RF-EMF) generated by a 5G base station simulator on basic physiological parameters and cognitive abilities of male Wistar rats across three different age groups (juvenile, adult, and early elderly).

Original information:

The effect of exposure to RF‑EMF from the laboratory simulator of 5G NR base station on physiological parameters and cognitive abilities of male Wistar rats of different ages

Original link:

https://www.nature.com/articles/s41598-024-60862-5

Journal information:

Scientific Reports, IF=4.6

1.Experimental animals and grouping: 60 male Wistar rats of different ages were selected and divided into juvenile group (5-6 weeks old), adult group (10-11 weeks old), and early elderly group (17-18 weeks old), with 20 rats in each group, further divided into experimental and control groups.

2.RF electromagnetic field exposure: The experimental group of rats was exposed to RF electromagnetic fields (RF-EMF) generated by a 5G base station simulator for 4 weeks. The control group of rats was in the same environment but not exposed to RF-EMF. The 5G base station simulator was built using software-defined radio (ADALM-Pluto), amplifiers (Ampleon), and antennas, as shown in Figures 1 and 2, ensuring that the RF electromagnetic field dose complied with the guidelines of the International Commission on Non-Ionizing Radiation Protection (ICNIRP).

Using the ADALM-Pluto software-defined radio (SDR) configured to periodically generate a frame of 5G NR downlink within the n40 (2.4 GHz) operating range, generating a signal bandwidth of 15 MHz. The signal simulated the transmission of user data and control information from the base station. A cascaded amplifier was used to amplify the signal on a board with a gain of 28 dB. The combined antenna connected to the cascaded amplifier output measures 240×168 mm, with a gain of approximately 7 dB. The resultant power at the antenna input was 0.0891 W. The use of a combined antenna, which is a combination of electric and magnetic dipoles, means that the far field forms at a distance corresponding to the wavelength used for radiation (approximately 12 cm).

For the current animal irradiation configuration, it can be observed that the incident power density of electromagnetic radiation decreases with increasing distance from the antenna. When estimating SAR for this configuration, the distance from the antenna should be considered. Therefore, for this configuration, the whole-body SAR estimation is calculated as follows:

Figure 1. Exposure setup.

Figure 2. Experimental photo.

3.Physiological parameter measurement: Weekly measurements of body weight, rectal temperature, and skin surface temperature of the rats were conducted to assess their physiological status.

4.Cognitive ability assessment: After the RF electromagnetic field exposure ended, the rats underwent the Morris water maze test to evaluate their spatial learning and memory abilities. The test recorded the time and path taken to find the hidden platform, as well as the number of errors.

After preliminary training of the rats, a pool with a diameter of 1.5 meters and a height of 0.6 meters was used, with a hidden platform (diameter 10 cm) and three different geometric objects as landmarks on the walls of the pool. The positions of these landmarks and the starting point remained constant. The water temperature in the pool was 22 ± 1°C. Each training test lasted 60 seconds, with the testing time recorded using a stopwatch. The time taken for successful swimming (the seconds required for the rats to find the hidden platform) was determined, and the average successful swimming time for each group of rats was calculated. The percentage of successful swimming was then calculated. If a trial failed, and the rat did not find the hidden platform within 60 seconds, the animal was placed on the platform for 10-15 seconds. Each rat underwent four training tests daily for four days (on the 1st, 2nd, 3rd, and 7th days).

5.Statistical analysis: Non-parametric Mann-Whitney tests were used to statistically analyze the differences in body weight, body temperature, and Morris water maze test results between the experimental and control groups, with p<0.05 set as the significance level.

6.Data recording and presentation: The body weight, body temperature, water maze test time, and other indicators for each rat were recorded, and the data were presented as means ± standard error.

This study assessed the impact of RF-EMF generated by the 5G NR base station simulator on basic physiological parameters and cognitive abilities of male Wistar rats across three age groups (juvenile, adult, and early elderly). The main experimental results are as follows:

1.Body weight changes: Throughout the experiment, there were no statistically significant differences in body weight changes between the rats of different age groups exposed to 5G RF-EMF and the control rats, as shown in Table 1.

Table 1. Body weight (grams) of Wistar rats studied during the experiment. Data are presented as means ± standard deviation.

2.Visceral organ weight coefficients: The visceral organ weight coefficients of the rats exposed to 5G RF-EMF also showed no statistically significant differences compared to the corresponding age control rats, as shown in Table 2.

Table 2. Visceral organ weight coefficients of male rats after five weeks of exposure to 5G RF-EMF (expressed as a percentage of body weight). Data are presented as means ± standard deviation.

3.Rectal temperature and skin surface temperature: Throughout the experiment, there were no statistically significant differences in rectal temperature and skin surface temperature between the rats of different age groups exposed to 5G RF-EMF and the control rats, as shown in Tables 3 and 4.

Table 3. Rectal temperature (degrees Celsius) of rats during the experiment. Data are presented as means ± standard deviation.

Table 4. Skin surface temperature (degrees Celsius) of rats during the experiment. Data are presented as means ± standard deviation.

4. Morris water maze test: The results of the Morris water maze test showed that there were no statistically significant differences in spatial learning and memory abilities between the rats of different age groups exposed to 5G RF-EMF and the control rats, as shown in Tables 5 and Figure 3.

All the animals in the studied age groups showed behavioral dynamics in the Morris water maze within the normal range: the successful swimming time accelerated, and the percentage of successful swimming increased from the first day of testing to the fourth day. The juvenile rats in the control group and the experimental group (exposed to RF-EMF 5G) performed better on the first day of testing (average swimming time) than the corresponding early elderly animal group, but their performance was slightly lower than that of the adult and early elderly rats on the seventh day of testing. Due to the effectiveness of the Morris water maze test in detecting memory and learning functions, we hypothesize that juvenile Wistar rats learn faster than early elderly rats, but adult and early elderly rats have better memory than juvenile rats. There were no differences in behavioral performance in the Morris water maze between the control group rats and those exposed to RF-EMF 5G in each age group.

Table 5. Testing of male Wistar rats in the Morris water maze across the studied age groups (N = 10). Data are presented as means ± standard deviation.

Figure 3. Spatial learning and memory status during Morris water maze training in different groups: (A) juvenile rats; (B) adult male rats; (C) early elderly male rats.

5. Passive swimming: In the Morris water maze test, the exposed rats of different age groups “refused” passive swimming faster than the control rats, indicating different execution strategies, as shown in Table 6.

Most passive swimming occurred on the first day of testing, usually after the first or second attempt. Some mice, mainly juvenile control group mice, maintained a tendency for passive swimming in subsequent tests. However, juvenile experimental group mice escaped the tendency for passive swimming faster than the corresponding control group. This may also indicate that RF-EMF promotes training in juvenile Wistar rats. It is worth noting that during prolonged passive swimming, the animals’ fur becomes wet, requiring significant effort to stay afloat. In the third day of testing, all adult mice escaped the tendency for passive swimming, and even one early elderly control mouse still floated on the seventh day. Clearly, these differences are related to the age of the animals and their individual differences in assessing their surroundings and choosing behavioral strategies.

Table 6. Number of Wistar rats in each age group undergoing passive swimming (over 60 seconds) during the Morris water maze test.

This study is the first to evaluate the long-term effects of RF electromagnetic fields generated by a 5G NR base station simulator on male Wistar rats across different age groups. The results indicate that exposure to 2.4 GHz RF electromagnetic fields below ICNIRP limit values does not significantly affect the weight, temperature, and cognitive abilities of the rats. These results provide a reference for further evaluating the potential impact of 5G base stations on public health. The study will further investigate the effects of 5G RF electromagnetic fields on female Wistar rats to predict the impact of 5G base stations on the overall population.

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