Unknown authors
Researchers used a normalizing waveguide reflectometer with less than 1 mW output power to measure reflection, transmission, and absorption in a WR 284 waveguide for anesthetized mice weighing 5.30 to 16.32 grams and measuring 4.5 to 7.7 centimeters in length over 2.5 to 4.2 GHz. Mice were positioned centrally in the waveguide with their length parallel to the propagation direction facing the incident wave. Absorption did not appear to change for up to 5 hours after death across the frequency range. From 24 mice, resonant frequency correlated with length (f = 6.084 - 0.419l, r=0.987) and weight (f = 4.679 - 0.1266w, r=0.952). SAR values showed increased slope through resonance and normalized SARs were consistent with literature values at 2.45 GHz.
Unknown authors
Unknown authors
James D. Fahnestock, Ralph W. Logan
Joseph M. Lary, David L. Conover, William E. Murray
The authors reviewed and critically evaluated the radiofrequency biological effects literature through 1982. The review indicated that there appears to be a threshold for adverse biological effects in animals at a specific absorption rate of about 2 W/kg. At SARs between 1.8 and 4.5 W/kg, adverse effects included death, temperature increases exceeding 3%, hemorrhagic lesions, staggering and spasms in chicks, and extreme agitation in dogs. At SARs below 1.8 W/kg no clearly adverse effects were reported, but measurable temperature increases and physiological changes occurred in the 0.17 to 1.8 W/kg range. At SARs below 0.17 W/kg no temperature increases were reported and most effects involved calcium efflux or blood-brain barrier permeability.
Hubert Fischer, Horst Müller
R. J. Lindquist
D.M. Deffenbaugh, R.J. Spiegel, J.R. Mann
Researchers modeled the human body numerically to determine thermal response under varied electromagnetic exposures by modifying heat transfer equations to account for absorbed electromagnetic energy. The body was represented as cylindrical segments sized to statistical 2.5%, 50%, and 97.5% anthropometry, and the combined code output temperatures at 61 discrete locations plus thermoregulatory responses such as vasoconstriction, vasodilation, shivering, and sweating. In a typical simulation at 80 MHz with 10 mW/cm² incident power, a hot spot appeared in the lower thigh, and at power levels above about 20 mW/cm² core temperatures rose uncontrollably, indicating failure of protective heat control mechanisms.
Marcia Lowery, Kenneth Dobbie
Vernon E. Rose et al.
Early standards treated 10 mw/cm2 as a maximum permissible level that should not be exceeded and considered only power density. Later standards introduced time-weighted exposure concepts allowing levels above 10 mw/cm2 for limited durations. The 1966 USASI standard set a protection guide at 10 mw/cm2 averaged over 0.1 hour and used an energy density of 1 mwh/cm2 for shorter periods.
Martin L. Meltz
Unknown authors
Unknown authors
The notice describes a possible radio frequency interference problem where oven leakage fields enter the readout box and may cause erroneous readings. Users should keep the readout box as far from the microwave oven and its leakage fields as possible by keeping the cable extended. Calibration is generally needed only once a year, not every six months, unless probe damage or instrument defect is suspected.
John F. Davis et al.
The system records the stimulation series and EEG responses on tape, forms the tape into a loop, and plays it through a gated integrator to plot the averaged response amplitude at selected time points. With recording at 33 ¼ ips and play- back at 15 ips, the analysis proceeds at four times the speed of the original experiment. However, since as many as one hundred points may have to be plotted, the analysis can still run to several hours. At present, the speed ratio is limited to 4:1 by considerations of transient response and information bandwidth.
Unknown authors
Roger Budd, Przemyslaw Czerski, LeRoy W. Schroeder
Researchers infected African green monkey kidney cells with herpes simplex virus and exposed them to a pulsed electromagnetic field for varying periods up to 48 hours. After 48 hours, they counted viral plaques and measured plaque size. Two experiments found no statistically significant differences in plaque numbers between exposed and control cultures. An initial suggestion of larger plaques in longer exposures was not confirmed in a second experiment with more uniform cell monolayers. The authors concluded that the screening system did not detect a biological effect of the pulsed electromagnetic field, though the device has been shown to affect immune cell functions in other studies.
Jacques ERRERA
Howard E. Clark
Unknown authors
Edward H. Grant, Susan E. Keefe, Shin Takashima
The study investigated the dielectric behavior of bovine serum albumin. Measurements were made from 200 MHz to 10,000 MHz at pH values 3.5, 4.5, 7.0, and 8.5 and concentrations ranging from 0.78 to 21%. A dielectric mixture theory was used to estimate the amount of bound water as a function of concentration and pH.
Unknown authors
Researchers performed transient thermographic measurements on a full-size human head phantom filled with muscle-equivalent material, irradiated by a quarter-wave monopole antenna excited at 100 watts and 456.65 MHz. The maximum specific absorption rate (SAR) occurred when the antenna tip was at the bridge or tip of the nose, while a flat surface like the forehead reduced peak SAR to about one-third of the maximum. Thermal diffusion corrections applied to data at one-inch antenna-to-model spacing yielded a peak SAR of about 200 W/kg in a small superficial region at the bridge of the nose.
Luis MIRO, Robert LOUBIERE, André PFISTER
Sol M. Michaelson, Herman P. Schwan
Unknown authors
John C. Mitchell
Experimental studies showed that lens opacities developed when intraocular temperatures reached 45-55°C, with a threshold around 100-150 mW/cm² applied for 60-100 minutes. The review found no cumulative effect from repeated EMR exposures unless each single exposure caused irreparable injury. Retrospective studies of radar operators and microwave workers found no increased cataract incidence or risk. The authors concluded that heat alone is responsible for lens damage following single high-intensity EMR exposures, based on hypothermic studies showing no cataracts under cooling.
