By National Council on Radiation Protection and Measurements
This record examines the literature on organic results of publicity to modulated radiofrequency (RF) power to figure out no matter if current publicity criteria and instructions must be converted extra to take modulation into consideration. Modulation happens in a wide selection of varieties really expert for radar, instant communications, broadcast communications, and business techniques with the end result that many waveforms, pulse widths, spectral houses, and temporal styles desire attention. In pulse modulation the RF strength is quickly switched off and on, while amplitude modulation produces a regularly altering point of RF strength. Frequency-modulated RF power has sign amplitudes that stay primarily consistent, yet fluctuate in frequency inside of a few narrowly prescribed variety and extra heavily resembles nonmodulated RF strength than pulsed or amplitude modulated RF fields. For radar, pulses as a rule have periods measured in fractions of a microsecond to some microseconds. periods among pulses (or pulse teams) are significantly longer leading to low responsibility cycle, that's, RF power is on for a small fraction of time in the course of every one interval. yet pulsed signs used for communications platforms could have intervals within the diversity of milliseconds, larger accountability cycles, and extra modulation beneficial properties. really good army structures represent a subcategory with very excessive, short pulses.
desk of Contents
2. In vitro reports
three. In vivo experiences
four. Human reviews
five. Epidemiological reviews
6. Biophysical issues
7. dialogue and Conclusions
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Extra info for Biological Effects of Modulated Radiofrequency Fields
1978). “Ionic factors in release of 45Ca++ from chick cerebral tissue by electromagnetic fields,” Proc. Natl. Acad. Sci. USA 75, 6314–6318. F. (1984). A. S. Environmental Protection Agency, Research Triangle Park, North Carolina). C. E. (1979). “Induction of calcium-ion efflux from brain tissue by radio-frequency radiation: Effects of modulation frequency and field strength,” Radio Sci. 14, 93–98. A. M. (1980). “Induction of calcium-ion efflux from brain tissue by radiofrequency radiation: Effect of 43 ©NCRP 2005 – All rights reserved COMPLIMENTARY COPY Single user authorization only, copying and networking prohibited 44 / REFERENCES sample number and modulation frequency on the power density window,” Bioelectromagnetics 1, 35–43.
Exposures to such pulses are, in principle, permissible under some contemporary exposure guidelines. However, such exposures are associated with specialized military weapon systems. Human beings are very unlikely to experience inadvertent exposures to such intense pulsed RF energy. Some animal studies have reported biological effects of RF energy modulated sinusoidally or by long- or short-duration pulses, sometimes at low average power levels. Unfortunately, the research on animals and cell and tissue systems exposed under these conditions is sparse and scattered over a variety of waveforms, experimental designs, animal species, and reported biological effects.
The investigators themselves suggested noncausal explanations for the weak associations they found. In a study of military career personnel in Poland, Szmigielski (1996) found an increased cancer morbidity rate for RF/microwave exposed personnel with the highest risks for leukemia. 05. 82). However, the study had serious design weaknesses, including bias in reporting exposure (Elwood, 1999), which prevents drawing any firm conclusions from its results. The number of cases observed and expected are not given and the report does not mention the age differences between the exposed and comparison groups.