Research on electromagnetic radiation from laptop computers, combining RF emissions (WiFi, Bluetooth) and ELF magnetic fields from electronics.
Your laptop sits inches from your body for hours each day, emitting radiofrequency radiation from its WiFi antenna and extremely low frequency magnetic fields from its internal components. These emissions span a remarkably wide range, from 50 Hz power frequencies up to 5.8 GHz wireless signals, creating what researchers call a "mixed exposure environment" right on your lap or desk. What makes laptops particularly concerning from an EMF perspective is their proximity to your body combined with duration of use.
Shallom JM et al. · 2002
Researchers exposed chick embryos to athermal 915 MHz microwave radiation to test for induction of the stress protein Hsp70. Hsp70 levels increased within 2 hours, reaching a maximum about 30% above controls by 3 hours. Embryos pre-exposed to microwave radiation before hypoxic stress had significantly higher survival after re-oxygenation than non-exposed controls (P < 0.05).
Zhang MB, He JL, Jin LF, Lu DQ. · 2002
Researchers studied whether 2450-MHz microwave radiation interacts with the chemical mitomycin C (MMC) to produce genotoxic effects in human lymphocytes in vitro. Blood cells from a male donor and a female donor were exposed to 2450-MHz microwaves at 5.0 mW/cm2 for 2 h, to MMC alone for 24 h, or to MMC for 24 h following microwave exposure. Microwave exposure alone did not significantly increase comet lengths compared with controls, but combined microwave plus MMC exposure produced significantly longer comet lengths than MMC alone at doses of 0.025 microgram/mL or higher.
Lass L et al. · 2002
The study enrolled 100 subjects (37 female, 63 male) and randomly assigned them to an exposed group (10-20 min, 0.158 mW cm(-2)) or a sham-exposed group. The aim was to examine low-level 7 Hz-modulated 450 MHz radiation effects on human performance in visually presented neuropsychological tasks associated with attention and short-term memory. A battery of three different tests measured attention and short-term memory. The results of tasks 1 and 3 showed a significant increase in variances of errors (p<0.05) in the exposed versus the sham-exposed group. The results of task 2 indicated a significant decrease in errors (p<0.05) in the exposed group.
Unknown authors · 2002
Researchers exposed Ku80-deficient xrs5 cells and Ku80-proficient CHO-K1 cells to ELF electromagnetic fields. ELF field exposure alone did not affect cell survival, cell cycle distribution, or protein expression in either cell line. In xrs5 cells, ELF exposure after irradiation inhibited G1 cell cycle arrest, increased bcl-2 expression, and decreased p53, phospho-p53, caspase-3, and p21 protein levels. ELF exposure for 10 hours after irradiation reduced X-ray-induced apoptosis in xrs5 cells from about 1.7% to 0.7%, but this effect was not observed in CHO-K1 cells.
Paulraj R, Behari J · 2002
Researchers exposed 35-day-old Wistar rats to low-level continuous 2.45 GHz microwaves for 2 hr/day over 35 days at a power density of 0.34 mW/cm2 with a specific absorption rate of 0.1 W/kg. Exposed rats showed a significant increase in calcium ion efflux and ornithine decarboxylase activity and a significant decrease in calcium-dependent protein kinase activity in brain tissue. The authors suggested that the radiation affects membrane-bound enzymes linked to cell proliferation and differentiation, indicating a possible tumor-promoting role.
Testylier G, Tonduli L, Malabiau R, Debouzy JC · 2002
Rats were exposed to 2.45 GHz continuous wave at 2 or 4 mW/cm(2) for 1 h during the day, or to 800 MHz modulated at 32 Hz at 200 mW/cm(2) for 1 or 14 h during the night. Exposure at 4 mW/cm(2) caused a significant 40% decrease in mean acetylcholine release from hippocampus, maximal at 5 h post exposure. Fourteen-hour nighttime exposure at 800 MHz induced a significant 43% decrease in acetylcholine release during 11 p.m.-4 a.m. compared to control rats.
Tafforeau M et al. · 2002
Researchers exposed flax seedlings to a 1-minute cold shock or a 2-hour GSM telephone radiation at 0.9 GHz and observed epidermal meristem production. They performed a SIMS analysis of inorganic cations in hypocotyl tissue from control and calcium-deprived seedlings. The analysis revealed decreases in calcium, sodium, and potassium and an increase in magnesium without substantially changing the divalent-to-monovalent cation ratio.
Unknown authors · 2002
Researchers exposed 10-day-old mice to a 1 mT, 60 Hz magnetic field for 2 hours and measured DNA damage at multiple time points using the alkaline comet assay. They also measured apoptosis in the external granule cell layer of the cerebellum at 0 and 24 hours using the TUNEL assay. Increased DNA damage was detected by tail ratio at 2 hours but not by the other comet assay parameters, and no increase in apoptosis was observed compared to sham-exposed mice.
Mueller CH, Krueger H, Schierz C · 2002
This double-blind laboratory experiment tested whether people can perceive a 50 Hz electric and magnetic field at 100 V/m and 6 μT, and whether self-reported electromagnetic hypersensitivity (EHS) is related to that ability. A total of 63 volunteers, 49 with self-reported EHS and 14 controls, each judged 10 sham and 10 exposed two-minute blocks in randomized order. Seven of the 63 subjects reached a statistically significant result, but there was no relevant difference between self-reported EHS subjects and controls in perception success rate or in the number and types of symptoms reported.
Stopczyk D et al. · 2002
Researchers assessed the effect of mobile phone electromagnetic fields on SOD-1 activity and MDA level in human blood platelets exposed to 900 MHz for 1, 3, 5, and 7 minutes. SOD-1 activity was significantly depleted after 1, 5, and 7 minutes of exposure and increased after 3 minutes compared with controls. MDA concentration increased significantly after 1, 5, and 7 minutes and decreased after 3 minutes compared with controls. The authors concluded that oxidative stress from microwave exposure may cause adverse cellular changes and systemic disturbances.
Takahashi S et al. · 2002
Researchers investigated the mutagenic potential of 1.5 GHz electromagnetic near fields using brain tissues of Big Blue mice. Male BBM were locally exposed to EMF in the head region at 2.0, 0.67, and 0 W/kg specific absorption rate for 90 min/day, 5 days/week, for 4 weeks. There was no significant variation in the frequency of independent mutations of the lacI transgene in the brains. Deletion mutations were slightly increased in both the high and low EMF exposure groups as compared with the sham-exposed group, but the differences were not statistically significant.
Bortkiewicz A, Pilacik B, Gadzicka E, Szymczak W. · 2002
Unknown authors · 2002
Researchers exposed differentiating IMR-32 neuroblastoma cells to 60 Hz magnetic fields at 50, 100, and 200 microT for 4 hours. They measured APP695 mRNA levels using northern hybridization with Digoxygenin-labeled probes. The results provided no support for any relationship between APP695 gene transcription and either differentiation age or magnetic field exposure.
Hanada E, Hoshino Y, Oyama H, Watanabe Y, Nose Y. · 2002
Researchers tested the effect of wireless LAN communication on medical electronic equipment and the effect of electronic equipment on wireless LAN communication. They observed nine pieces of electronic equipment in operating mode while transmitting radio waves from a wireless LAN. No equipment malfunction occurred even with the access point very close to the equipment surface during data transmission. Medical equipment caused little change in wireless communication effectiveness, but electric knives and a remote patient monitor reduced the reception rate to about 60%. Wireless LAN speed was temporarily reduced only when a microwave oven was close to and facing the access point.
Pologea-Moraru R, Kovacs E, Iliescu KR, Calota V, Sajin G · 2002
Researchers studied the effects of low-power microwaves at 2.45 GHz on the membrane fluidity of rod photoreceptor cells. The researchers expected the retina to be very sensitive to microwave irradiation due to the polar character of photoreceptor cells and high water content.
Miyakoshi, J., Yoshida, M., Tarusawa, Y., et al. · 2002
Unknown authors · 2002
Researchers analyzed expression of immediate early response genes c-fos, c-jun, and c-myc in human glioblastoma T98G cells exposed to 1-500 μT 60 Hz elliptically polarized magnetic fields for up to 3 h. No statistically significant differences were found in gene expression ratios at both transcriptional and translational levels for c-fos and c-jun at 30 min and for c-myc at 180 min after serum stimulation. Similarly, exposure to linearly or circularly polarized 500 μTr fields produced no significant change in expression ratios at both transcriptional and post-transcriptional levels.
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%.
Unknown authors · 2002
However, research reports indicate that living cells may respond to power-frequency fields well below the thermal noise limits. The study proposes that published thermal arguments may not fully account for all membrane force fields of thermal origin, and that a full accounting could show smaller net thermal noise fields in the power-frequency range.
Unknown authors · 2002
This 2002 theoretical study challenged the widely accepted belief that thermal noise in cell membranes would prevent power frequency electric and magnetic fields from affecting human cells. The researchers argued that previous thermal noise calculations were incomplete and that when all thermal forces are properly accounted for, the actual noise may be lower than thought, potentially allowing environmental EMF to influence cellular membranes.
Liu Y, Weng E, Zhang Y, Hong R. · 2002
Researchers exposed mice to a 50 Hz sinusoidal electromagnetic field at 0.2 mT or 6.0 mT for 2 weeks, and measured markers of the antioxidant system and cell membrane fluidity in brain and liver tissue. Malondialdehyde content in brain and liver increased with exposure, while total antioxidant capability decreased at both field strengths. When electromagnetic field exposure was combined with lead, the researchers observed synergic effects on lipid peroxidation.
Logani MK, Agelan A, Ziskin MC. · 2002
The study examined the effect of millimeter electromagnetic waves on catalase activity in mouse blood to understand mechanisms involved in its reduction. SKH-1 hairless mice were irradiated on their midbacks with 42.2±0.2 GHz millimeter waves at an incident power density of 31±5 mW/cm2 and a peak SAR of 622±100 W/kg. MW irradiation before or after cyclophosphamide administration did not significantly reduce the toxic effect of cyclophosphamide on catalase activity in mouse blood.
Liu X, Shen H, Shi Y, Chen J, Chen Y, Ji A. · 2002
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.
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.