EMF Research Studies

Biological effects of prolonged exposure to ELF electromagnetic fields in rats: III. 50 Hz electromagnetic fields

Unknown authors · 1998

Acute exposure to a 60 Hz magnetic field affects rats' water-maze performance

Unknown authors · 1998

Rats were trained in six sessions to locate a submerged platform in a water maze and exposed to a 1 mT, 60 Hz magnetic field for one hour before each session. There was no significant difference in learning to locate the platform between exposed and control rats. Exposed rats had significantly slower swim speed and spent less time in the target quadrant during a probe trial, with different swim patterns.

Ultra-wideband electromagnetic pulses and morphine-induced changes in nociception and activity in mice.

Seaman RL, Belt ML, Doyle JM, Mathur SP · 1998

Researchers exposed CF-1 and C57BL/6 mice to ultra-wideband electromagnetic pulses and then tested nociception and locomotor activity. No effect of the pulses was found on nociception or activity in CF-1 mice after exposures of 15, 30, or 45 minutes at 600 pulses per second or 30 minutes at 60 pulses per second. Similarly, no effect was seen in C57BL/6 mice after 30 minutes at 60 or 600 pulses per second. Morphine-modified nociception and activity also showed no significant change after UWB exposure.

Lack of promoting effects of the electromagnetic near-field used for cellular phones (929.2 MHz) on rat liver carcinogenesis in a medium-term liver bioassay.

Imaida K et al. · 1998

Researchers exposed male F344 rats to a 929.2 MHz electromagnetic near-field for 90 minutes a day, five days a week, over six weeks. The exposed rats showed no significant difference in GST-P positive foci numbers or areas compared to sham-exposed rats. Maximum local specific absorption rates were 7.2 to 6.6 W/kg in the whole body and 2.0 to 1.7 W/kg in the liver.

The 1.5 GHz electromagnetic near-field used for cellular phones does not promote rat liver carcinogenesis in a medium-term liver bioassay.

Imaida et al. · 1998

Researchers exposed male F344 rats to a 1.439 GHz TDMA electromagnetic near-field for 90 minutes a day, 5 days a week, over 6 weeks. The rats were initiated with diethylnitrosamine and underwent partial hepatectomy at week 3. Peak liver SARs ranged from 1.91 to 0.937 W/kg and whole-body average SARs from 0.680 to 0.453 W/kg at 0.33 W antenna power. Exposure did not significantly alter the numbers or areas of GST-P-positive foci in the liver compared to sham-exposed rats. Serum levels of corticosterone, ACTH, and melatonin were increased in exposed rats.

Chronic, low-level (1.0 W/kg) exposure of mice prone to mammary cancer to 2450 MHz microwaves.

Frei et al. · 1998

Researchers exposed 100 C3H/HeJ mice to continuous-wave 2450 MHz RF radiation at 1.0 W/kg for 78 weeks, 20 hours per day, 7 days per week, while 100 mice were sham-exposed. There was no significant difference in mammary tumor incidence between exposed mice (38%) and sham-exposed mice (30%). Latency to tumor onset was similar: 62.5 weeks for exposed mice and 62.0 weeks for sham-exposed mice. Histopathological evaluation found no significant difference in malignant, metastatic, or benign neoplasms between groups.

DNA damage in rat brain cells after in vivo exposure to 2450 MHz electromagnetic radiation and various methods of euthanasia.

Malyapa RS et al. · 1998

Researchers exposed male Sprague-Dawley rats to 2450 MHz continuous-wave microwaves for two hours at 1.2 W/kg specific absorption rate. No significant differences in DNA damage were found between sham-exposed and irradiated rats in either the cerebral cortex or hippocampus, regardless of euthanasia method. Rats euthanized by CO2 asphyxia showed more intrinsic DNA damage and greater experiment-to-experiment variation than those euthanized by guillotine. The authors concluded that guillotine euthanasia is the most appropriate method for DNA damage studies. The study did not confirm previous reports of DNA damage from 2450 MHz microwave exposure.

Effect of environmental temperature on the interactive developmental toxicity of radiofrequency radiation and 2-methoxyethanol in rats.

Nelson BK, Conover DL, Krieg EF Jr, Snyder DL, Edwards RM · 1998

Researchers tested whether environmental temperature changes the interactive developmental toxicity of radiofrequency radiation and 2-methoxyethanol. Environmental temperature affected the specific absorption rate needed to maintain a given colonic temperature but did not affect the interactive developmental toxicity. The results add to evidence that developmental toxicity of radiofrequency radiation is associated with colonic temperature, not with specific absorption rate. Fetuses were examined for external malformations on gestation day 20.

Changes of nitric oxide synthase in hippocampus and cerebellum of the rat following exposure to electromagnetic pulse.

Ding G, Xie X, Zhang L et al. · 1998

Researchers studied the distribution of nitric oxide synthase (NOS) expression in the hippocampus and cerebellum of rats after exposure to electromagnetic pulse (EMP). The number of NOS-positive neurons and staining intensity in the hippocampus decreased at 1.5 and 24 hours after exposure. At 48 hours, the number of NOS-positive neurons returned to control levels, but staining intensity remained lower. NOS expression in the cerebellum showed no obvious changes. The authors suggest that decreased hippocampal NOS expression relates to learning and memory obstruction after EMP exposure.

[Stimulation of production of tumor necrosis factor by murine macrophages when exposed in vio and in vitro to weak electromagnetic waves in the centimeter range].

Novoselova ET, Fesenko EE. · 1998

Researchers studied whether weak electromagnetic waves in the centimeter range could affect tumor necrosis factor production in macrophages from mice. Whole-body microwave irradiation of male NMRI mice, exposure of macrophages in vitro, and irradiation of culture medium with 8.15-18 GHz at a power density of 1 microW/cm2 each caused a significant enhancement of tumor necrosis factor production in peritoneal macrophages.

Ultra-wideband electromagnetic pulses: lack of effects on heart rate and blood pressure during two-minute exposures of rats.

Jauchem JR et al. · 1998

Researchers exposed 10 anesthetized Sprague-Dawley rats to ultra-wideband electromagnetic pulses at three different pulse repetition rates. Exposures at 50, 500, and 1000 pulses per second resulted in no significant changes in heart rate or mean arterial blood pressure during the two-minute exposures or in the two minutes after. The results suggest that acute whole-body exposure under these conditions does not have an immediate detrimental effect on these cardiovascular system variables.

Interaction of low level modulated RF radiation with Na+¯K+-ATPase.

Behari J, Kunjilwar KK, and Pyne S · 1998

Researchers studied the effect of low-level amplitude-modulated radiofrequency radiation on Na+–K+-ATPase activity in the brains of developing male Wistar rats aged 23 days. Rats were exposed to carrier wave frequencies of 147 MHz and its sub-harmonic frequencies 73.5 and 36.75 MHz, amplitude modulated at 16 and 76 Hz, for 30–35 days at 3 hours per day. Na+–K+-ATPase activity increased by around 19–20% in rats exposed with amplitude modulation at 16 Hz, and by around 15–16% in rats exposed with amplitude modulation at 76 Hz, compared to controls. The researchers concluded that the effect on Na+–K+-ATPase activity was insensitive to the carrier wave frequencies under investigation.

Acute exposure to a 60 Hz magnetic field increases DNA strand breaks in rat brain cells

Unknown authors · 1997

Rats were exposed for 2 h to a 60 Hz magnetic field at flux densities of 0.1, 0.25, and 0.5 mT. DNA strand breaks in brain cells were assayed by microgel electrophoresis 4 h postexposure. Single-strand DNA breaks increased after exposure to 0.1, 0.25, and 0.5 mT, while double-strand DNA breaks increased at 0.25 and 0.5 mT.

Frequency of micronuclei in the peripheral blood and bone marrow of cancer-prone mice chronically exposed to 2450 MHz radiofrequency radiation.

Vijayalaxmi et al. · 1997

C3H/HeJ mice prone to mammary tumors were exposed to 2450 MHz RF radiation at 1.0 W/kg for 20 hours per day, 7 days a week, over 18 months, with sham-exposed controls and positive controls treated with mitomycin C. The incidence of micronuclei in peripheral blood and bone marrow did not differ significantly between RF-exposed and sham-exposed groups. Positive controls treated with mitomycin C showed significantly elevated micronuclei frequencies. A separate analysis of mice that developed mammary tumors also found no significant differences in micronuclei frequency between exposure groups.

DNA synthesis and cell proliferation in C6 glioma and primary glial cells exposed to a 836.55 MHz modulated radiofrequency field.

Stagg RB, Thomas WJ, Jones RA, Adey WR · 1997

Researchers exposed transformed and normal rat glial cells to an 836.55 MHz packet-modulated RF field at power densities of 0.09, 0.9, and 9 mW/cm2, with SARs from 0.15 to 59 muW/g. Primary rat glial cells showed no significant differences in DNA synthesis between sham and RF-exposed conditions for either log-phase or serum-starved cultures. C6 glioma cells exposed at 5.9 muW/g SAR showed small but significant increases in thymidine incorporation in 38% of experiments. Growth curves showed no differences between sham and RF-exposed cultures for either cell type, and doubling times of C6 glioma cells did not differ significantly.

The absence of interference between GSM mobile telephones and implantable defibrillators: an in-vivo study. Groupe Systemes Mobiles

Sanmartin M et al. · 1997

Researchers tested 30 patients with eight different defibrillator models using three GSM mobile phones under continuous electrocardiographic monitoring. Phones were placed in close contact with the defibrillator can and precordium at two angles, and tested during calling, established contact for 15 seconds, and ringing, with the protocol repeated during pacing. No cases of electromagnetic interference were observed. One patient presented non-sustained ventricular tachycardia episodes during the tests that were detected by the defibrillator. These results suggest that electromagnetic interference by GSM mobile phones are not a probable cause of implantable defibrillators dysfunction.

Brain tumour development in rats exposed to electromagnetic fields used in wireless cellular communication.

Salford LG, Brun A, Persson BRR · 1997

Researchers used Fischer 344 rats of both sexes with implanted glioma cells (RG2 and N32) in a matched-pair design. Starting on day 5 after inoculation, rats were exposed for 7 hours a day, 5 days a week for 2–3 weeks to 915 MHz continuous or pulse-modulated microwaves. The study found no significant difference in tumour size between exposed and control animals. Tumour size was estimated as the volume of an ellipsoid after histopathological examination of all brains.

Millemetre waves inhibit the synergistic effect of calcium ionophore A23187 and phorbol ester in neutrophil respiratory burst

Safronova VG et al. · 1997

Age does not affect thermal and cardiorespiratory responses to microwave heating in calorically restricted rats.

Ryan KL, Walters TJ, Tehrany MR, Lovelace JD, Jauchem JR · 1997

Researchers exposed three age groups of calorically restricted rats to 35 GHz microwaves until death while measuring temperature, heart rate, and mean arterial pressure. Before exposure, the age groups showed no significant differences in measured parameters. Microwave heating increased temperatures at all measured sites, but temperatures at death did not differ between age groups. Heart rate increased throughout exposure in a statistically identical manner across all age groups, and mean arterial pressure was initially well maintained before precipitously declining until death with no age-related difference. Respiration rate was not altered by microwave exposure in any group, and the exposure time required to induce death did not differ among age groups.

The lack of effects of nonthermal RF electromagnetic fields on the development of rat embryos grown in culture.

Klug S, Hetscher M, Giles S, Kohlsmann S, Kramer K, · 1997

Researchers exposed 9.5-day-old rat embryos for up to 36 hours to radiofrequency electric and magnetic fields with modulation frequencies of 16, 60, and 120 Hz. The exposure included electric field strengths of 60 and 600 V/m, magnetic inductions of 0.2 and 2.0 microtesla, and specific absorption rates of 0.2, 1.0, and 5.0 W/kg. Neither the electric nor the magnetic fields interfered significantly with normal embryo growth and differentiation when assessed on day 11.5 using a scoring system, photographs, histology, and protein content.

Exposure of nerve growth factor-treated PC12 rat pheochromocytoma cells to a modulated radiofrequency field at 836.55 MHz: effects on c-jun and c-fos expression.

Ivaschuk OI et al. · 1997

Researchers exposed nerve growth factor-treated PC12 rat pheochromocytoma cells to a packet-modulated 836.55 MHz radiofrequency field at power densities of 0.09, 0.9, and 9 mW/cm2 for 20, 40, or 60 minutes, with an intermittent 20-minute on/off regimen. Sham-exposed cells served as controls, and c-fos and c-jun expression was measured by Northern blot analysis of total RNA. C-fos transcript levels did not change after 20 minutes at any intensity, while c-jun transcripts decreased by 38% only after 20 minutes at 9 mW/cm2.

Focus formation of C3H/10T1/2 cells and exposure to a 836.55 MHz modulated radiofrequency field.

Cain CD, Thomas DL, Adey WR · 1997

The study tested whether a TDMA-modulated RF field and the tumor promoter TPA together increase focus formation of transformed cells cocultured with parental C3H/10T1/2 murine fibroblasts. Cell cultures were exposed to an 836.55 MHz TDMA-modulated field at specific absorption rates of 0.15, 1.5, and 15 μW/g in a repeating cycle of 20 minutes on and 20 minutes off continuously for 28 days. RF exposure did not significantly alter TPA-induced focus formation at any of the tested exposure levels across multiple independent experiments.

Evaluation of bone density in rats after hydrocortisone and microwave radiation

Olchowik G · 1997

Researchers investigated the influence of hydrocortisone and microwave radiation on bone in rats. Hydrocortisone hemisuccinate was administered intraperitoneally for 12 weeks with concomitant microwave irradiation at two power densities. The results indicated a protective effect of electromagnetic microwave radiation on bone tissue exposed to corticotherapy.

Interactions of radiofrequency radiation on 2-methoxyethanol teratogenicity in rats

Nelson BK, Conover DL, Shaw PB, Snyder DL, Edwards RM · 1997

Researchers exposed pregnant rats to radiofrequency radiation that raised colonic temperature to 42.0°C for 10 minutes while administering various doses of 2-methoxyethanol on gestation day 13. Dose-related developmental toxicity from 2-methoxyethanol occurred both with and without the radiation exposure. However, the radiation changed the shape of the dose-effect curve for 2-methoxyethanol.

Electromagnetic millimeter waves increase the duration of anaesthesia caused by ketamine and chloral hydrate in mice.

Rojavin MA, Ziskin MC · 1997

Researchers injected BALB/c mice with ketamine 80 mg/kg or chloral hydrate 450 mg/kg and exposed them to 61.22 GHz millimeter waves at 420 W/kg peak specific absorption rate for 15 minutes. Millimeter wave exposure increased anesthesia duration by about 50% compared to sham exposure, which had no effect.