Lauri Puranen

Mobile Phone Radiation and the Developing Brain: Behavioral and Morphological Effects in Juvenile Rats

Abstract Kumlin, T., Iivonen, H., Miettinen, P., Juvonen, A., van Groen, T., Puranen, L., Pitkäaho, R., Juutilainen, J. and Tanila, H. Mobile Phone Radiation and the Developing Brain: Behavioral and Morphological Effects in Juvenile Rats. Radiat. Res. 168, 471–479 (2007). The increasing use of mobile phones by children and teenagers has raised concerns about their safety. Addressing such concerns is difficult, because no data are available on possible effects from long-term exposure to radiofrequency (RF) fields during the development of the nervous system. Possible morphological and functional changes were evaluated in the central nervous system of young male Wistar rats exposed to 900 MHz mobile phone signal for 2 h/day on 5 days/week. After 5 weeks of exposure at whole-body average specific energy absorption rates of 0.3 or 3.0 W/kg or sham exposure, six rats per group were examined histologically, and the remaining 18 rats per group were subjected to behavioral tests. No degenerative changes, dying neurons, or effects on the leakage of the blood-brain barrier were detected. No group differences were observed in the open-field test, plus maze test or acoustic startle response tests. In the water maze test, however, significantly improved learning (P = 0.012) and memory (P = 0.01) were detected in rats exposed to RF fields. The results do not indicate a serious threat to the developing brain from mobile phone radiation at intensities relevant to human exposure. However, the interesting finding of improved learning and memory warrants further studies.

Effects of mobile phone radiation on X-ray-induced tumorigenesis in mice.

Abstract Heikkinen, P., Kosma, V-M., Hongisto, T., Huuskonen, H., Hyysalo, P., Komulainen, H., Kumlin, T., Lahtinen, T., Lang, S., Puranen, L. and Juutilainen, J. Effects of Mobile Phone Radiation on X-Ray-Induced Tumorigenesis in Mice. Radiat. Res. 156, 775–785 (2001). The increased use of mobile phones has raised the question of possible health effects of such devices, particularly the risk of cancer. It seems unlikely that the low-level radiofrequency (RF) radiation emitted by them would damage DNA directly, but its ability to act as a tumor promoter is less well characterized. In the current study, we evaluated the effect of low-level RF radiation on the development of cancer initiated in mice by ionizing radiation. Two hundred female CBA/S mice were randomized into four equal groups at the age of 3 to 5 weeks. The mice in all groups except the cage-control group were exposed to ionizing radiation at the beginning of the study and then to RF radiation for 1.5 h per day, 5 days a week for 78 weeks. One group was exposed to continuous NMT (Nordic Mobile Telephones)-type frequency-modulated RF radiation at a frequency of 902.5 MHz and a nominal average specific absorption rate (SAR) of 1.5 W/kg. Another group was exposed to pulsed GSM (Global System for Mobile)-type RF radiation (carrier-wave frequency 902.4 MHz, pulse frequency 217 Hz) at a nominal average SAR of 0.35 W/kg. The control animals were sham-exposed. Body weight, clinical signs, and food and water consumption were recorded regularly. Hematological examinations and histopathological analyses of all lesions and major tissues were performed on all animals. The RF-radiation exposures did not increase the incidence of any neoplastic lesion significantly. We conclude that the results do not provide evidence for cancer promotion by RF radiation emitted by mobile phones.

Assessment of the magnetic field exposure due to the battery current of digital mobile phones.

Abstract— Hand-held digital mobile phones generate pulsed magnetic fields associated with the battery current. The peak value and the waveform of the battery current were measured for seven different models of digital mobile phones, and the results were applied to compute approximately the magnetic flux density and induced currents in the phone-user’s head. A simple circular loop model was used for the magnetic field source and a homogeneous sphere consisting of average brain tissue equivalent material simulated the head. The broadband magnetic flux density and the maximal induced current density were compared with the guidelines of ICNIRP using two various approaches. In the first approach the relative exposure was determined separately at each frequency and the exposure ratios were summed to obtain the total exposure (multiple-frequency rule). In the second approach the waveform was weighted in the time domain with a simple low-pass RC filter and the peak value was divided by a peak limit, both derived from the guidelines (weighted peak approach). With the maximum transmitting power (2 W) the measured peak current varied from 1 to 2.7 A. The ICNIRP exposure ratio based on the current density varied from 0.04 to 0.14 for the weighted peak approach and from 0.08 to 0.27 for the multiple-frequency rule. The latter values are considerably greater than the corresponding exposure ratios 0.005 (min) to 0.013 (max) obtained by applying the evaluation based on frequency components presented by the new IEEE standard. Hence, the exposure does not seem to exceed the guidelines. The computed peak magnetic flux density exceeded substantially the derived peak reference level of ICNIRP, but it should be noted that in a near-field exposure the external field strengths are not valid indicators of exposure. Currently, no biological data exist to give a reason for concern about the health effects of magnetic field pulses from mobile phones.

Effects of mobile phone radiation on UV-induced skin tumourigenesis in ornithine decarboxylase transgenic and non-transgenic mice.

Purpose: The effects of low-level radiofrequency radiation (RFR) on ultraviolet (UV)-induced skin tumorigenesis were evaluated in ornithine decarboxylase (ODC) and non-transgenic mice. Materials and methods: Transgenic female mice over-expressing the human ODC gene and their non-transgenic littermates (20 animals in the cage control group, and 45-49 animals in the other groups) were exposed for 52 weeks to UV radiation or a combination of UV radiation and pulsed RFR. The UV dose was 240 Jm−2 (1.2 ×human minimum erythemal dose) delivered three times a week. One group of animals was exposed to Digital Advanced Mobile Phone System (DAMPS)-type RFR, the other group to Global System for Mobile (GSM)-type RFR at a nominal average specific absorption rate of 0.5 W kg−1, 1.5 h day−1, for 5 days a week. The skin was carefully palpated weekly for macroscopic tumours. Histopathological analyses of all skin lesions and of a specified dorsal skin area were performed on all animals. Results: UV exposure resulted in development of macroscopic skin tumours in 11.5 and 36.8% of non-transgenic and transgenic animals, respectively. The RFR exposures did not give a statistically significant effect on the development of skin tumours in either transgenic or non-transgenic animals, or in combined analysis, but tumour development appeared slightly accelerated especially in non-transgenic animals. No effects of RFR exposures were found on excretion of 6-hydroxymelatonin sulphate into urine or on polyamine levels in dorsal skin. Conclusion: RFR exposures did not significantly enhance skin tumourigenesis. However, the slightly accelerated tumour development may warrant further evaluation.

Investigation of Co-genotoxic Effects of Radiofrequency Electromagnetic Fields In Vivo

Abstract Verschaeve, L., Heikkinen, P., Verheyen, G., Van Gorp, U., Boonen, F., Vander Plaetse, F., Maes, A., Kumlin, T., Mäki-Paakkanen, J., Puranen, L. and Juutilainen, J. Investigation of Co-genotoxic Effects of Radiofrequency Electromagnetic Fields In Vivo. Radiat. Res. 165, 598–607 (2006). We investigated the possible combined genotoxic effects of radiofrequency (RF) electromagnetic fields (900 MHz, amplitude modulated at 217 Hz, mobile phone signal) with the drinking water mutagen and carcinogen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX). Female rats were exposed to RF fields for a period of 2 years for 2 h per day, 5 days per week at average whole-body specific absorption rates of 0.3 or 0.9 W/kg. MX was given in the drinking water at a concentration of 19 μg/ml. Blood samples were taken at 3, 6 and 24 months of exposure and brain and liver samples were taken at the end of the study (24 months). DNA damage was assessed in all samples using the alkaline comet assay, and micronuclei were determined in erythrocytes. We did not find significant genotoxic activity of MX in blood and liver cells. However, MX induced DNA damage in rat brain. Co-exposures to MX and RF radiation did not significantly increase the response of blood, liver and brain cells compared to MX exposure only. In conclusion, this 2-year animal study involving long-term exposures to RF radiation and MX did not provide any evidence for enhanced genotoxicity in rats exposed to RF radiation.

No Effects of Radiofrequency Radiation on 3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone-Induced Tumorigenesis in Female Wistar Rats

Abstract Heikkinen, P., Ernst, H., Huuskonen, H., Komulainen, H., Kumlin, T., Mäki-Paakkanen, J., Puranen, L. and Juutilainen, J. No Effects of Radiofrequency Radiation on 3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone-Induced Tumorigenesis in Female Wistar Rats. Radiat. Res. 166, 397–408 (2006). This study evaluated possible effects of radiofrequency (RF) radiation on tumorigenesis induced by the mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) given in drinking water. Female Wistar rats aged 7 weeks at the beginning of the experiments were randomly divided into four groups of 72 animals: a cage-control group and three MX-exposed groups (a daily average dose of 1.7 mg MX/kg body weight for 104 weeks), of which two were exposed to 900 MHz pulsed RF radiation and the third served as a sham-RF-radiation group. The RF-radiation groups were exposed 2 h per day, 5 days per week for 104 weeks at nominal whole-body average SARs of 0.3 W/kg and 0.9 W/kg. Complete histopathology was performed on the rats of the three MX-exposed groups. The tumor types and incidences observed in the MX-exposed animals were similar to those reported earlier in MX-exposed female Wistar rats. RF radiation did not statistically significantly affect mortality or organ-specific incidence of any tumor type. The only statistically significant difference was an increase in the combined frequency of vascular tumors of the mesenteric lymph nodes in the high-RF-radiation group compared to the sham-RF-radiation group. However, additional histopathological analysis of the cage-control animals suggested that this difference was due to unusually low frequency of this type of tumor in the sham-RF-radiation group rather than a high frequency in the high-RF-radiation group. With respect to non-neoplastic findings, statistically significant differences between the RF-radiation groups and the sham-RF-radiation group were observed only for single findings in the lacrimal glands, lungs, liver and skin. Such changes are commonly seen in aged rats and were considered to be unrelated to RF radiation. The results of the present study do not support co-carcinogenic effects of low-level long-term RF-radiation exposure in rats.

Radio frequency currents induced in the human body for medium-frequency/high-frequency broadcast antennas

Radio frequency currents in the human body, induced by high-frequency and medium-frequency high-power broadcast antennas, were studied theoretically and experimentally. An analytical formula was derived to calculate the foot currents in a grounded semispheroidal model of the human body. The model agrees within 30% with the results given by the standard formula presented by Gandhi on the basis of measurements with humans. Near 100 kHz, the model predicts a decrease of 14% of the current dissipated in the human body, which is due to the beta relaxation of the cells. The effect of the body and foot-contact impedances were studied with the aid of a simplified equivalent circuit which showed that the body impedance does not considerably affect the foot current below 10 MHz. The normalized foot currents measured in front of the broadcast antennas were within 30% agreement of the currents calculated with the Gandhi formula from the electric fields measured at a height of 1 m. The foot currents are induced by vertical electric fields for both medium-frequency and high-frequency antennas in spite of a strong horizontal component in the latter case. The distance at which the occupational exposure limit of 200 mA was exceeded in the worst (maximum coupling) case was 50 m for the high-frequency antenna and < 14 m for the medium-frequency antenna. In the latter case, the radio frequency shocks resulting from touching ungrounded metallic bodies impose a practical limit to about 40 m.

Specific absorption rate and electric field measurements in the near field of six mobile phone base station antennas.

In this article, the exposure to radio frequency electromagnetic fields was studied in close proximity (distances of 10, 100, 300, and 600 mm) to six base station antennas. The specific absorption rate (SAR) in 800 mm x 500 mm x 200 mm box phantom as well as unperturbed electric field (E) in air was measured. The results were used to determine whether the measurement of local maximum of unperturbed electric field can be used as a compliance check for local exposure. Also, the conservativeness of this assessment method compared to the ICNIRP basic restriction was studied. Moreover, the assessment of whole-body exposure was discussed and the distance ranges presented in which the ICNIRP limit for local exposure could be exceeded before the limit for whole-body SAR. These results show that the electric field measurement alone can be used for easy compliance check for the local exposure at all distances and for all antenna types studied. However, in some cases when the local peak value of E was compared directly to the ICNIRP reference level for unperturbed E, the exposure was overestimated only very slightly (by factor 1.1) compared to the basic restriction for localized SAR in a human, and hence these results can not be generalized to all antenna types. Moreover, it was shown that the limit for localized exposure could be exceeded before the limit for the whole-body average SAR, if the distance to the antenna was less than 240 mm.

Setup and dosimetry for exposing anaesthetised pigs in vivo to 900 MHz GSM mobile phone fields

The aim of this study was a dosimetrical analysis of the setup used in the exposure of the heads of domestic pigs to GSM-modulated radio frequency electromagnetic fields (RF-EMF) at 900 MHz. The heads of pigs were irradiated with a half wave dipole using three different exposure routines; short bursts of 1-3 s at two different exposure levels and a continuous 10-min exposure. The electroencephalogram (EEG) was registered continuously during the exposures to search for RF-EMF originated changes. The dosimetry was based on simulations with the anatomical heterogeneous numerical model of the pig head. The simulation results were validated by experimental measurements with the exposure dipole and a homogeneous liquid phantom resembling the pig head. The specific absorption rate (SAR), defined as a maximum average over 10 g tissue mass (SAR(10g)), was 7.3 W/kg for the first set of short bursts and 31 W/kg for the second set of short bursts. The SAR(10g) in the continuous 10-min exposure was 31 W/kg. The estimated uncertainty for the dosimetry was +/-25% (K = 2).

Radiation Hazard Assessment of Pulsed Microwave Radars

Observed biological effects of pulsed microwave radiation are reviewed and the exposure standards for microwave radiation are summarized. The review indicates that the microwave auditory effect is the only well-established specific effect in realistic exposure situations. The threshold for the effect depends on the energy density per pulse and may be as low as 20 mJ/m2 for people with low hearing threshold. Energy density limits have been included in the most recent exposure standards. A new battery-operated, hand-held meter developed for measurements of pulse power densities around scanning radar antennas is described, and a simple new model for the calculation of power density in the main beam of radar antennas is presented. In the near field measured values differed from the calculated values by 2-3 dB.