Unknown authors · 2008
Researchers developed child head models based on magnetic resonance imaging and analyzed maximum SAR over 10 g in seven child and six adult heterogeneous head models. They also assessed SAR over 1 g in specific tissues for both child and adult head models. Simulations showed that maximum SAR over 10 g differed little between adults and children relative to variability, but maximum SAR in 1 g of peripheral brain tissue was about two times higher in child models aged 5–8 years than in adult models, with no difference for older children.
Nagaoka T, Kunieda E, Watanabe S · 2008
Researchers used an existing Japanese adult voxel model and three-dimensional deformation to create models representing average-size Japanese children at 3, 5, and 7 years old. The models consist of cubic voxels 2 mm on each side segmented into 51 tissues and organs. They calculated whole-body-averaged and tissue-averaged specific absorption rates for the child models exposed to plane waves from 30 MHz to 3 GHz and compared the results with scaled down adult models. They also determined the incident electric-field strength needed to produce a whole-body-averaged SAR of 0.08 W kg(-1), the ICNIRP basic restriction for general public exposure.
George DF, Bilek MM, McKenzie DR. · 2008
Researchers studied the effect of 2,450 MHz microwaves on protein unfolding using surface plasmon resonance sensing. They used citrate synthase which binds to alpha crystallin chaperone when unfolded, and compared microwave heating with ambient heating and combined heating to the same final temperature. Microwaves caused a significantly higher degree of unfolding than conventional thermal stress at the same maximum temperature.
Dimbylow PJ, Hirata A, Nagaoka T. · 2008
The study intercompared the HPA male and female models NORMAN and NAOMI with the NICT male and female models TARO and HANAKO. Particular emphasis was placed on how dielectric properties are assigned to tissues such as skin and fat and on the consequences of different SAR calculation algorithms at higher frequencies. Whole-body SAR calculations were performed at three institutions for a vertically polarized plane wave incident on the front of the body from 30 MHz to 3 GHz under isolated conditions.
Unknown authors · 2008
Unknown authors · 2008
Researchers exposed rats to 2.45 GHz microwave radiation (similar to WiFi frequency) at very low power levels for 3 hours daily over 30 days. The exposed rats showed significant learning and memory problems, along with elevated stress hormones and brain cell death in the hippocampus. When researchers blocked the stress hormone pathway, the cognitive damage was partially prevented.
Sinha RK · 2008
Researchers exposed male rats to 2450 MHz microwave radiation and assessed thyroid hormones and behavior. Exposed rats showed hyperactivity and aggression, with significant changes in open-field and elevated plus-maze tests. Thyroid hormone levels changed, with T3 decreasing and T4 increasing, correlating with behavioral changes.
Inoue S, Motoda H, Koike Y, Kawamura K, Hiragami F, Kano Y. · 2008
Exposure to 2.45 GHz microwave irradiation at 200 W increased neurite outgrowth frequency about 10-fold compared to non-irradiated controls. The increase was prevented by adding a p38 MAPK inhibitor. Microwave treatment did not cause toxicity, unlike heat shock at 45°C.
Peyman A, Holden SJ, Watts S, Perrott R, Gabriel C · 2007
The dielectric properties of pig cerebrospinal tissues were measured in vivo and in vitro in the frequency range of 50 MHz-20 GHz. White matter and spinal cord showed significant variation as a function of animal age while no age-related variations were recorded for grey matter. The in vitro study included tissue from pigs weighing approximately 10, 50, and 250 kg to examine variation with age. Total combined measurement uncertainty was calculated at each frequency point and reported over representative frequency regions. Comparisons were made between the in vivo and in vitro data and with literature from the past decade.
Unknown authors · 2007
Researchers measured radiofrequency fields from wireless local area networks using Wi-Fi technology against background RF fields in the frequency range 75 MHz to 3 GHz. They conducted 356 measurements at 55 sites including residences, commercial spaces, healthcare and educational institutions, and other public spaces in the U.S., France, Germany, and Sweden. Measurements were taken under conditions that would result in the higher end of exposures, including close to Wi-Fi access points and at a distance of approximately 1 m from a laptop uploading and downloading large files. In all cases, measured Wi-Fi signal levels were very far below international exposure limits (IEEE C95.1-2005 and ICNIRP) and in nearly all cases far below other RF signals in the same environments.
Dimbylow P. · 2007
Researchers used finite-difference time-domain calculations to estimate SAR from 20 MHz to 3 GHz in hybrid voxel-mathematical models of the pregnant female. Mathematical models of the developing foetus at 8-, 13-, 26- and 38-week gestation were converted into voxels and combined with the reference adult female model, NAOMI at a resolution of 2 mm. The study calculated the electric field values needed to produce the ICNIRP public exposure restriction of 2 W kg(-1) when averaged over 10 g of the foetus.
Unknown authors · 2007
The paper discusses the phenomenon, mechanism, power requirement, pressure amplitude, and auditory thresholds of microwave hearing. Microwave pulse hearing involves electromagnetic waves from hundreds of MHz to tens of GHz, unlike normal hearing which uses sound pressure waves. The microwave auditory effect does not come from direct interaction with auditory nerves but from a thermoelastic wave launched by pulse absorption in soft tissues. This thermoelastic wave travels by bone conduction to the inner ear and activates cochlear receptors like normal hearing. The paper emphasizes human exposures to wireless communication fields and MRI coils.
Unknown authors · 2007
This 2007 study explains how humans and animals can actually hear microwave pulses, a phenomenon where electromagnetic waves create audible sounds inside the head. The research shows that pulsed microwaves heat tissue, creating pressure waves that travel through bone to the inner ear, where they're perceived as clicking or buzzing sounds. This finding has important implications for understanding exposure to wireless devices and MRI equipment.
Schmid G et al. · 2007
A numerical model of the human middle and inner ear was developed at 0.1 mm resolution based on a real human tissue sample. The model was inserted into a commercial head model and FDTD computations were run for handheld device exposures from 400 to 3700 MHz. Highest absorption occurred at 400 MHz with 166 microW in the labyrinth and 12 microW in the vestibulocochlear nerve for a 500 mW device. For typical mobile phone frequencies (900 MHz and 1850 MHz) and output power values (250 mW and 125 mW), absorbed RF power was more than one order of magnitude lower than the values given above. The researchers concluded that temperature-related biologically relevant effects from typical handheld devices are unlikely.
Wang KJ, Yao K, Lu DQ. · 2007
Christ A, Samaras T, Klingenböck A, Kuster N. · 2006
The study investigated electromagnetic near-field absorption in layered biological tissue from 30 MHz to 6000 MHz. Two effects can increase SAR in layered tissue versus homogeneous liquid: standing wave effects at larger distances depending on frequency and fat thickness, and high local skin absorption from reactive E-fields in the very close near-field. A conservative exposure estimate can be obtained by applying a multiplication factor of 1 to 3 to current dosimetric values.
Keshvari J, Keshvari R, Lang S. · 2006
Wang J et al. · 2006
Researchers exposed A172 cells to 2450 MHz high-frequency electromagnetic fields at SARs of 5-200 W/kg and included heat controls at 38-44°C. HSP70 expression increased in a time- and dose-dependent manner at SARs above 50 W/kg for 1-3 hours, similar to heat controls. HSP27 expression did not change significantly with HFEMF exposure or heating, but HSP27 phosphorylation increased transiently at 100 and 200 W/kg, exceeding the effect of heating at 40-44°C, peaking after 1 hour at 100 W/kg.
Takashima Y et al. · 2006
Researchers exposed cells to radio frequency electromagnetic fields at 2.45 GHz to examine cell growth, survival, and cell cycle distribution across a wide range of specific absorption rates. When cells were exposed to a continuous RF field at SARs from 0.05 to 100 W/kg for 2 h, cellular growth rate, survival, and cell cycle distribution were not affected. At 200 W/kg, the cell growth rate was suppressed and cell survival decreased, and the temperature of the medium rose to 44.1 degrees C. The researchers suggested that the proliferation disorder is caused by the thermal effect.
Paulraj R, Behari J · 2006
The control group was sham irradiated. The study revealed a statistically significant decrease in PKC activity in the hippocampus compared to the rest of the brain and controls. Electron microscopy showed an increase in glial cell population in the exposed group.
Vijayalaxmi · 2006
Researchers exposed peripheral blood lymphocytes from healthy volunteers to 2.45 GHz or 8.2 GHz pulsed-wave RF radiation for 2 hours. They measured chromosomal aberrations and micronuclei to assess cytogenetic damage. The RF-exposed lymphocytes showed no significant increase in damage compared to sham-exposed lymphocytes. Gamma-irradiated positive control cells showed significantly more damage than both RF-exposed and sham-exposed cells.
Trosic I, Busljeta I. · 2006
Researchers exposed rats to 2.45 GHz microwave radiation at a whole-body SAR of 1.25+/-0.36 W/kg for 2 hours per day, 7 days a week. Bone marrow polychromatic erythrocytes increased on days 8 and 15, and peripheral blood polychromatic erythrocytes increased on days 2 and 8. Bone marrow micronucleated PCE frequency increased on day 15, and peripheral blood micronucleated PCEs increased on day 8, but all values declined nearly to control levels by the end of the experiment.
Sun LX, Yao K, Jiang H, He JL, Lu DQ, Wang KJ, Li HW · 2006
Researchers exposed cultured human lens epithelial cells to 217 Hz modulated microwave radiation at four SAR levels for 2 hours. DNA single strand breaks were measured using the comet assay immediately after irradiation and at 30 and 60 minutes afterward. At the highest dose, significant DNA damage remained one hour after irradiation and cell proliferation was significantly decreased.
Lee S et al. · 2005
The study used the serial analysis of gene expression (SAGE) method to measure genome-wide gene expression changes in cultured human HL-60 cells exposed to pulsed 2.45 GHz RF fields. After a 2-hour exposure, 221 genes showed altered expression, increasing to 759 genes after 6 hours. Apoptosis-related genes were upregulated while cell cycle genes were downregulated, with no significant increase in heat shock genes.
Lee S et al. · 2005
Researchers exposed human blood cells to 2.45 GHz radiofrequency radiation (the same frequency used in WiFi and microwave ovens) and found it altered the activity of hundreds of genes. After just 2 hours, 221 genes changed their expression, increasing to 759 genes after 6 hours. The affected genes were involved in cell death and cell division processes, suggesting biological effects occur through non-heat mechanisms.
