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Effects of high- frequency electromagnetic fields on DNA strand breaks using comet assay method

Miyakoshi, J., Yoshida, M., Tarusawa, Y., et al. · 2002

Some present problems and a proposed experimental phantom for SAR compliance testing of cellular telephones at 835 and 1900 MHz

Unknown authors · 2002

The paper compares maximum allowable powers for cellular telephones at 835 and 1900 MHz under ANSI/IEEE, ICNIRP, and a proposed IEEE modification. It shows the ANSI/IEEE guideline is the most conservative, ICNIRP allows 2.5-3 times higher maximum radiated power, and the proposed modification allows up to 50% higher power. Peak 1 g SAR in smaller head models is up to 56% higher at 1900 MHz and up to 20% higher at 835 MHz than in larger models. Plastic ear models yield SARs up to two or more times smaller than realistic anatomic models, and a 2 mm thin shell phantom with lossy ear is proposed to match anatomic SARs within +/- 15%.

The microarray study on the stress gene transcription profile in human retina pigment epithelial cells exposed to microwave radiation.

Liu X, Shen H, Shi Y, Chen J, Chen Y, Ji A. · 2002

Assessment of guidelines for limiting exposures to emf using methods of probabilistic risk analysis.

Thompson CJ, Anderson V, Rowley JT. · 2002

The broad objective was to assess radiofrequency exposure limits, hazard thresholds, and safety factors using probabilistic risk analysis. Analysis of SAR variables including conductivity and permittivity of grey brain matter and radiated field strengths supported the hypothesis that SAR values are lognormally distributed. The probability that SAR exceeds a threshold was derived and shown to be very low for handset SARs relative to allowable standard limits. The analysis focused on peak radiofrequency SAR values in the brain from digital mobile telephones operating at approximately 900 MHz.

Micronucleus induction after whole-body microwave irradiation of rats.

Trosic I, Busljeta I, Kasuba V, Rozgaj R. · 2002

Researchers exposed adult male Wistar rats to continuous 2450 MHz radiofrequency microwave radiation for 2 hours a day, 7 days a week, for up to 30 days, at a power density of 5–10 mW/cm2. Peripheral blood smears were examined for micronuclei in polychromatic erythrocytes as an indicator of genotoxicity. Micronuclei per 1000 PCEs were significantly increased after eight irradiation treatments compared with sham-exposed controls. The researchers noted that an adaptive mechanism in both erythrocytopoiesis and genotoxicity likely appeared during the subchronic irradiation treatment.

Chronic Exposure to a GSM-like Signal (Mobile Phone) Does Not Stimulate the Development of DMBA-Induced Mammary Tumors in Rats: Results of Three Consecutive Studies.

Bartsch H et al. · 2002

Researchers tested a GSM-like RF signal on mammary tumors induced by DMBA in female Sprague-Dawley rats as a model for human breast cancer. Three experiments were carried out under strictly standardized conditions using a GSM-like signal at 900 MHz pulsed at 217 Hz. The overall results showed no statistically significant effect of RF-field exposure on tumor latency, and cumulative tumor incidence was unaffected as well. The researchers concluded that low-level RF radiation does not appear to possess carcinogenic or cancer-promoting effects on DMBA-induced mammary tumors.

Influence of a radiofrequency electromagnetic field on cardiovascular and hormonal parameters of the autonomic nervous system in healthy individuals.

Braune S, Riedel A, Schulte-Monting J, Raczek J. · 2002

The study investigated the hypothesis that exposure to EMFs can increase sympathetic vasoconstrictor activity. Forty healthy young males and females underwent a single-blind, placebo-controlled protocol on two different days with randomized EMF and placebo periods. The EMF exposure was a GSM-like signal at 900 MHz, pulsed with 217 Hz, 2 W, delivered by a mobile phone on the right side of the head. Blood pressure, heart rate, cutaneous capillary perfusion, and serum levels of norepinephrine, epinephrine, cortisol, and endothelin were measured. Systolic and diastolic blood pressure increased about 5 mmHg during the protocol, but the changes were independent of EMF exposure.

Growth and maturation of the nematode Caenorhabditis elegans following exposure to weak microwave fields.

de Pomerai DI, Dawe A, DjerbibL, Allan, Brunt G, Daniells C. · 2002

Researchers investigated growth rate and maturation proportion in C. elegans exposed to prolonged microwave fields at 25°C in synchronized cultures of wild-type larvae. Microwave exposure significantly increased growth rate by 8–11% and maturation proportion by 28–40%. Mild heat treatment at 28°C decreased growth rate by 10% and almost abolished maturation proportion, showing effects opposite to microwave exposure.

DNA damage and micronucleus induction in human leukocytes after acute in vitro exposure to a 1.9 GHz continuous-wave radiofrequency field.

McNamee JP et al. · 2002

Human blood cultures were exposed to a 1.9 GHz continuous-wave radiofrequency field for 2 hours at SARs of 0.0, 0.1, 0.26, 0.92, 2.4, and 10 W/kg while temperature was maintained at 37.0 ± 0.5°C. DNA damage was measured immediately after exposure using the alkaline comet assay with four parameters, and micronucleus formation was assessed using the cytokinesis-block micronucleus assay. No evidence of increased primary DNA damage was detected at any SAR tested. There was no significant difference in micronucleus incidence between exposed cultures and sham controls at any SAR.

DNA Damage in human leukocytes after acute in vitro exposure to a 1.9 GHz pulse-modulated radiofrequency field.

McNamee JP et al. · 2002

Blood cultures from human volunteers were exposed to an acute 1.9 GHz pulse-modulated radiofrequency (RF) field for 2 h using a series of six circularly polarized, cylindrical waveguides. Mean specific absorption rates (SARs) ranged from 0 to 10 W/kg and the temperature within the cultures during the exposure was maintained at 37.0 ± 0.5°C. DNA damage was quantified in leukocytes by the alkaline comet assay and the cytokinesis-block micronucleus assay. No evidence of increased primary DNA damage was detected by the comet assay and no significant differences in micronucleus frequency were found at any SAR tested.

DNA Damage in human leukocytes after acute in vitro exposure to a 1.9 GHz pulse-modulated radiofrequency field.

McNamee JP et al. · 2002

Canadian researchers exposed human white blood cells to 1.9 GHz radiofrequency radiation (similar to cell phone frequencies) for 2 hours at various power levels up to 10 W/kg. They found no DNA damage in the cells compared to unexposed controls, using two different laboratory tests to detect genetic harm. This study suggests that short-term RF exposure at these levels does not cause immediate DNA breaks in immune cells.

Changes in the dielectric properties of rat tissue as a function of age at microwave frequencies.

Peyman A, Rezazadeh AA, Gabriel C · 2001

Researchers measured dielectric properties of ten rat tissues at six ages from 130 MHz to 10 GHz. Results showed a general decrease in dielectric properties with age. The decrease was more apparent in brain, skull, and skin tissues than in abdominal tissues. The variation was attributed to changes in water content and organic composition.

GSM phone signal does not produce subjective symptoms.

Koivisto M et al. · 2001

Researchers studied the influence of pulsed radiofrequency electromagnetic fields from digital GSM mobile phones (902 MHz, 217 Hz pulse modulation) on subjective symptoms in healthy subjects using two single-blind experiments. The results did not reveal any differences between exposure and non-exposure conditions. Exposure durations were about 60 minutes in Experiment 1 and 30 minutes in Experiment 2. Subjects rated symptoms including headache, dizziness, fatigue, itching or tingling of the skin, redness on the skin, and sensations of warmth on the skin.

Changes in cellular proteins due to environmental non-ionizing radiation. I. Heat-shock protiens

S. Kwee, P. Raskmark & S. Velizarov · 2001

Researchers exposed transformed human epithelial amnion (AMA) cells to a microwave field simulating the GSM signal at 960 MHz for 20 minutes. The field generated a specific absorption rate (SAR) of 2.1 mW.kg−1 in the cells, and exposures were carried out at temperatures of 35, 37, and 40 ± 0.1°C. Higher amounts of Hsp-70 were found in exposed cells at 35 and 37°C compared with sham-exposed cells, while Hsp-27 showed no significant response. The researchers considered these effects athermal because the field strength was much lower than the safety standard for absence of heat generation by microwave fields.

Effects of radiofrequency exposure on the GABAergic system in the rat cerebellum: clues from semi-quantitative immunohistochemistry

Mausset A, de Seze R, Montpeyroux F, Privat A · 2001

Researchers injected rats with gamma-vinyl-GABA to increase GABA levels and then used immunohistochemistry and image analysis to measure cerebellar GABA content. They exposed rats to 900 MHz pulsed radiofrequency at 4 W/kg SAR and continuous waves at 32 W/kg SAR. Pulsed exposure selectively reduced the stained processes area in the Purkinje cell layer, while continuous exposure decreased optical density in all three cell layers. The authors noted that it is unknown whether these effects are partly due to local tissue heating.

Cytogenetic effects of 900 MHz (GSM) microwaves on human lymphocytes

Maes A, Collier M, Verschaeve L · 2001

Researchers investigated cytogenetic effects of 900 MHz radiofrequency fields using chromosome aberration and sister chromatid exchange frequency methods. They studied three exposure modes (continuous, pseudo-random, dummy burst) at power outputs from 0 to 50 W. Specific absorption rates ranged from 0 to 10 W/kg. The study examined effects of radiation alone and combined with mitomycin C and X-rays. Overall, no mutagenic or co-mutagenic effect was found.

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

Heikkinen P et al. · 2001

Researchers evaluated the effect of low-level RF radiation on cancer development initiated by ionizing radiation in mice. Two hundred female CBA/S mice were randomized into four equal groups at 3 to 5 weeks of age, and all groups except the cage-control group were exposed to ionizing radiation followed by RF radiation for 1.5 h per day, 5 days a week for 78 weeks. One group received continuous NMT-type RF radiation at 902.5 MHz and 1.5 W/kg SAR, another received pulsed GSM-type RF radiation at 902.4 MHz and 0.35 W/kg SAR, while controls were sham-exposed. RF radiation exposures did not significantly increase the incidence of any neoplastic lesion. The researchers concluded that the results do not provide evidence for cancer promotion by RF radiation from mobile phones.

Effect of Exposure to 900 MHz Radiofrequency Radiation on Intrachromosomal Recombination in pKZ1 Mice.

Sykes PJ, McCallum BD, Bangay MJ, Hooker AM, Morley AA. · 2001

Researchers studied the effect of pulsed 900 MHz radiofrequency radiation at 4 W/kg on somatic intrachromosomal recombination in the spleen of pKZ1 mice. Mice were exposed daily for 30 minutes to 900 MHz fields for 1, 5, or 25 days, and spleen sections were screened for DNA inversion events three days after the last exposure. There was no significant difference between control and treated groups in the 1- and 5-day exposure groups, but a significant reduction in inversions was found in the 25-day group.

Effect of Exposure to 900 MHz Radiofrequency Radiation on Intrachromosomal Recombination in pKZ1 Mice.

Sykes PJ, McCallum BD, Bangay MJ, Hooker AM, Morley AA · 2001

Researchers exposed mice to 900 MHz radiofrequency radiation (similar to cell phones) for up to 25 days to see if it affected DNA recombination in spleen cells. They found no effects after short exposures, but after 25 days of exposure, DNA recombination actually decreased below normal levels. While this wasn't the DNA damage scientists typically look for, it suggests RF radiation can alter how cells repair their DNA, though the health significance of this change remains unknown.

Effects of electromagnetic fields produced by radiotelevision broadcasting stations on the immune system of women.

Boscol P et al. · 2001

The study investigated the immune systems of 19 women with a mean age of 35 years who had been exposed to electromagnetic fields from radiotelevision broadcasting stations in their residential area for at least 2 years, with a mean exposure duration of 13 years. The exposed group had mean field levels of 4.3 plus or minus 1.4 V/m in the range 500 KHz to 3 GHz, while the control group had nearby residential exposure of less than 1.8 V/m. The exposed women showed statistically significant reductions in several immune cell types and lower in vitro production of IL-2 and interferon-gamma by peripheral blood mononuclear cells. The researchers concluded that high frequency electromagnetic fields reduce cytotoxic activity in the peripheral blood of women without a dose-response effect.

Symptoms experienced by users of digital cellular phones: a pilot study in a French engineering school.

Santini R et al. · 2001

Researchers conducted a questionnaire survey of 161 students and workers at a French engineering school about symptoms during digital cellular phone use. Users of 1800-MHz phones reported significantly more concentration difficulties than users of 900-MHz phones. Women using cellular phones complained of sleep disturbance significantly more often than men. Using both cellular phones and VDT significantly increased concentration difficulties. Longer daily calling duration and more calls per day were associated with more ear discomfort, warmth, and pricking.

Electromagnetic field of mobile phones affects visual event related potential in patients with narcolepsy.

Jech R et al. · 2001

Local vasodilator response to mobile phones.

Paredi P, Kharitonov SA, Hanazawa T, Barnes PJ · 2001

Researchers exposed eleven healthy adults to a 900 MHz mobile phone for 30 minutes and measured skin temperature, nasal nitric oxide, and nasal minimal cross-sectional area. On the side of the phone, skin temperature rose significantly by 2.3°C at 6 minutes, nasal nitric oxide tended to increase by 12.9% at 10 minutes, and minimal cross-sectional area decreased by 27% at 15 minutes. These changes were absent when an earpiece was used, and the opposite side showed no temperature or nitric oxide change but a 38% increase in minimal cross-sectional area.

Local vasodilator response to mobile phones.

Paredi P, Kharitonov SA, Hanazawa T, Barnes PJ. · 2001

Researchers measured biological changes in 11 healthy adults during 30-minute cell phone calls using 900 MHz phones. They found significant increases in skin temperature (up to 2.3°C), reduced nasal airway space (27% decrease), and elevated nitric oxide levels on the side of the head where the phone was held. These effects disappeared when participants used earpieces instead of holding phones directly against their heads.

Analysis of the influence of the cell geometry, orientation and cell proximity effects on the electric field distribution from direct RF exposure.

Sebastian JL, Munoz S, Sancho M, Miranda JM · 2001

Researchers calculated electric field intensity using the finite element method in single- and multilayer spherical, cylindrical, and ellipsoidal mammalian cell models exposed to 900 and 2450 MHz plane waves. They analyzed how cell geometry and orientation relative to the external field influence the electric field induced in the membrane and cytoplasm. The study found that cytoplasmic and extracellular bound water layers play a significant role in determining electric field intensity for cylindrical and ellipsoidal models.