MindNet is no longer active. Back to MindNet Index ================================================================ MindNet Journal - Vol. 1, No. 61a * [Part 1 of 2 parts] ================================================================ V E R I C O M M / MindNet "Quid veritas est?" ================================================================ The views and opinions expressed below are not necessarily the views and opinions of VERICOMM, MindNet, or the editors unless otherwise noted. Permission is given to reproduce and redistribute, for non-commercial purposes only, provided this information and the copy remain intact and unedited. Editor: Mike Coyle Assistant Editor: Rick Lawler Research: Darrell Bross Editor's Note: I am usually reticent to express my personal opinions about a paper such as this. It seems, to me, to be better to just let the information speak for itself and allow the reader to come to their own opinion about its veracity. However, the following article about GWEN, obviously written by the government agency that is responsible for its creation, is such an egregious example of disinformation, obfuscation, and selective referencing, that I feel I owe my subscribers a comment and explanation. The serious, and adverse health effects associated with exposure to even low-levels of RFR, which are largely discounted by this article, are well documented as a result of laboratory experiments, case history studies, and statistical studies done by many scientists and doctors. Below you will find a few excerpts from this article followed by rebuttals that directly contradict these excerpts. ...stated within: "A number of so-called "nonthermal" effects have been described in the scientific literature in connection with RFR exposure of laboratory animals and animal tissue at levels equal to or less than 0.4 W/kg (EPA 1986). These effects, involving the cellular, hematologic, reproductive, nervous systems, and others, are summarized in a review by Cahill and Elder (1984). The significance of these effects for public health is not clear, partly because the mechanisms responsible for them are not known." ...rebuttal: "...DARPA at the Institute for Defense Analysis...`certain events presumed to the threatening to the national interest served as the basis for ARPA's support for Project Pandora', and funds were given to Walter Reed [Medical Research Institute] early in 1965 `to evaluate the threat since it appeared to have strong behavioral and biomedical implications'...`cytogenic and histological studies of the brain suggested that comparable energies were damaging tissue' - _The_Zapping_of_America_ by Paul Brodeur, 1977, pg. 123. ...stated within: "_Cataracts_. It has been asserted in newspapers and other popular media that microwaves potentially cause cataracts. Scientific studies have indicated that microwaves can cause cataracts in experimental animals, but only if incident continuous-wave power densities are high..." ...rebuttal: "...the case received prominent mention in the bureau's [Bureau of Radiological Health] 1969 annual report to Congress. When Carpenter described it a the fifth annual symposium of the International Microwave Power Institute, which was held in Scheveningen, in the Netherlands, on October 7, 1970, he stated that it provided a `unique example of bilateral cataracts resulting from low-level microwave radiation.'" - _The_Zapping_of_America_ by Paul Brodeur, 1977, pg. 68. ...stated within: "_Birth Defects_. Birth defects (technically, teratogenesis) and developmental abnormalities after birth are always of public concern... Teratogenic studies associated with RFR have used a variety of animal models. The results indicate that a threshold of heat induction or temperature increase must be exceeded before teratogenic effects are produced. For the SARs associated with human exposure to GWEN RFR, there would be no detectable heating, so birth defects would be extremely unlikely." ...rebuttal: "That microwave radiation might have genetic effects had first been discovered back in 1959 by Dr. John H. Heller...at the New England Institute for Medical Research, in Ridgefield Conn., who observed gross chromosomal abnormalities in garlic-root tips that had been irradiated with microwaves at power levels far below those necessary to produce heat...in August 1975, members of Electromagnetic Radiation Management Advisory Council, OTP, & DoD met to review the findings of research pertaining to the genetic, hereditary, growth, and developmental effects of microwave and radio-frequency radiation, they learned that in eight out of fifteen projects low-level radiation had produced effects and changes in the test animals or genetic material." - _The_Zapping_of_America_ by Paul Brodeur, 1977, pg. 90. ...stated within: "_Endocrine System Effects_. Exposure of animals to RFR has produced... There do not appear to be any effects clearly demonstrated to be associated with nonthermogenic stimulation of the endocrine system or the associated parts of the CNS." ...rebuttal: "Soviet investigators also turned up a great number of endocrine responses to radio-frequency radiation, including increased thyroid activity, slight enlargement of the thyroid gland, sterility, and decreased lactation in nursing mothers." - _The_Zapping_of_America_ by Paul Brodeur, 1977, pg. 37. I could go on and on, but I think you see my point. Please keep this in mind as you read this document. I have also included below a few references excerpted from _Cross_Currents_ by Dr. Robert O. Becker that document the adverse effects of RFR. Aurell, E., and Tengroth, B. _Acta_Ophthalmologica_ 51 (1973):764. Report that microwaves can produce cataract at nonthermal levels and can damage the retina itself. Birge, R., et al. _Journal_of_the_American_Chemical_Society_ 109(1987):2090. Report that certain chemicals in the retina absorb microwaves to a high degree. Delgado, J.M.R., et al. _Journal_of_Anatomy_ 134 (1982):533. Reports on developmental defects in chick embryos exposed to various ELF frequencies. Garfinkel, I., and Savokhan, B. _Annals_of_the_New_York_Academy_ _of_Sciences_ 381 (1982):I. Report that the incidence of brain tumors rose between 1940 and 1977. Heller, J.H., and Teixeira-Pinto, A.A. _Nature_ 183 (1959):905. First report on the production of chromosomal abnormalities by fields at 27 MHz. Liboff, A, _Science_ 223 (1984):818. Report that a wide range of frequencies in the ELF-VLF range could increase the rate of DNA synthesis in dividing cells. ================================================================ GROUND WAVE EMERGENCY NETWORK (GWEN) Document courtesy of Julianne McKinney, Electronic Surveillance Project. September 1995 ---------------------------------------------------------------- Ground Wave Emergency Network (GWEN) --- 3.11 HEALTH 3.11.1 Definition of Resource Aspects of the GWEN program that might affect the health of the general public residing in the vicinity of GWEN facilities or potentially exposed to GWEN operations are related to exposure to radio frequency radiation (RFR). All radio transmission antennae are sources of RFR. The GWEN system would generate RFR from a 299-foot, low-frequency (LF) antenna and an ultrahigh-frequency (UHF) antenna located at each relay node (RN) station, and from a UHF antenna located at each input/output (I/O) station. The oscillation of current and voltage in a transmitting antenna results in the radiation of an outward-traveling field, or electromagnetic wave. By encoding information into this wave, messages can be transmitted to a receiving station in a manner analogous to AM, FM, and TV broadcasting and reception. The electromagnetic wave consists of an electric field, the E-field, and a magnetic field, the H-field. These electromagnetic waves constitute the RFR. The region beyond the distance of a few wavelengths of any transmission is known as the far field. The wavelengths for GWEN LF transmissions range from 1.7 to 2 kilometers; thus, the far field refers to the region beyond several kilometers from the RN stations. The region within a few wavelengths of the transmitting antenna is referred to as the near field. The electromagnetic field within this region is more complicated than in the far field. In addition to the primary propagating wave, there are nonpropagating fields which tend to dominate the near field. Because these nonpropagating fields decrease rapidly with distance, they become insignificant in the far field. 3.11.2 Issues and Concerns Although RFR is referred to as radiation, it does not cause ionization and should not be confused with radiation from radioactive sources. In general, RFR is associated with electromagnetic waves with frequencies ranging from approximately 10 kilohertz (kHz) to 300 gigahertz (GHz). Electromagnetic waves with higher frequencies than radio waves are, in ascending order of frequency, infrared waves, visible light, ultraviolet waves, X-rays, and gamma rays. Electromagnetic waves propagate energy in "packets" called photons. The energy of a photon is directly proportional to the frequency of the radiation. When the photon energies equal or exceed the binding energies of electrons to atoms, the radiation is capable of ionizing atoms and breaking electron bonds in biomolecules, thereby disrupting biochemical processes and causing genetic and other damage in biological organisms. Ultraviolet waves, X-rays, and gamma rays, are ionizing. However, the photon energies associated with the highest radio frequencies are several orders of magnitude lower than the weakest chemical bonds and they cannot ionize atoms or disrupt chemical bonding. Thus, RFR is nonionizing and does not create the same effect as radiation generated by radioactive sources. Its primary effect in biological organisms is to agitate molecules, that is, generate heat. At intensities that fall within present exposure standards, the rate of heat generation is negligible or is within the thermoregulatory capabilities of mammals and birds. There have been reports of some cases of accidental occupational exposure to RFR intensities that exceed present safety limits. In addition, the Environmental Protection Agency (EPA) has found that levels of field intensities in the FM and TV-broadcast bands exceed present exposure limits at certain sites that are accessible to the general public. Because of these few cases, some members of the public may perceive that there is a high risk associated with RFR regardless of intensity or frequency. Public concerns are centered on the potential for effects on humans due to both long- and short-term exposure to RFR at GWEN frequencies and exposure levels. These concerns may include the potential for shock hazards, birth defects, and cancer. 3.11.3 Regulatory Setting No federal, state, county, or municipal regulations exist for RFR exposure in the GWEN LF band (150 to 175 kHz). In July 1986, as part of its charge under federal law to develop RFR protection guides, the EPA published proposed alternatives for controlling public exposure to RFR and requested written comments. Other national and international agencies have published guidelines for RFR safety. _American_National_Standards_Institute_ (ANSI) has set safety levels for human exposure to RFR in the frequency range of 300 kHz to 100 GHz (ANSI, 1982), ANSI concluded that the reliable evidence of hazardous effects on animals is associated with whole-body-average specific absorption rates (SAR) above 4 watts/kilogram (W/kg) in animals. Using a safety factor of 10, the exposure limit was set at 0.4 W/kg. Since SAR is frequency-dependent in a manner that is species-specific, the power density limits that correspond to 0.4 W/kg vary with frequency. At resonant frequencies for humans (see section 3.11.6.2), this value of SAR corresponds to a power density of 1 milliwatt per square centimeter (mw/cm2). This limit on power density was specified for the frequency range of 30 to 300 MHz to include all possible resonant conditions for humans. The limit on power density for frequencies below this range can be increased inversely as the second power of the frequency while still maintaining a limit of 0.4 W/kg on the SAR. However, because there's a potential for shock and burns at high power densities, the ANSI subcommittee limited the power density to 100 mw/cm2 for frequencies below 3 MHz, extending down to 300 kHz. Using the assumption of plane waves, this power density limit corresponds to an E-field intensity of 632 volts per meter (V/m) and to an H-field intensity of 1.58 amperes per meter (A/m). While the ANSI standard would limit the SAR value to 0.4 W/kg averaged over the whole body, it allows a spatial peak (local) value of 8 W/kg averaged over any one gram of tissue. SARs, power densities, and squares of field intensities are averaged over any 6-minute period. The ANSI subcommittee did not provide any guidance for frequencies below 300 kHz; therefore, ANSI does not cover the GWEN LF band. The ANSI standard is applicable to the control of occupational and non-occupational exposures. _International_Radiation_Protection_Association_ (IRPA) provides interim guidelines on limits of exposure (IRPA 1984). While IRPA's occupational limits at resonance are the same as ANSI's, the limit for the general population is based on a safety factor of 50 relative to 4 W/kg, or 5 relative to 0.4 W/kg. The whole-body average SAR is limited to 0.08 W/kg, which corresponds to a power density of 0.2 mw/cm2 in the range of human resonant frequencies. The limit on the local SAR for the general population is reduced to 0.8 W/kg. As with the other standards, the power density limit rises as the frequency decreases from resonance. The limit for exposure to the public in the 100 kHz to 1 MHz frequency range is a power density of 2 mw/cm2, with corresponding limits to E-field and H-field intensities set at 87 V/m and 0.23 A/m, respectively. These limits would apply to the GWEN LF transmissions. _National_Council_on_Radiation_Protection_and_Measurements_ (NCRP 1986) recently recommended RFR limits for the public. These limits are similar to IRPA's limits for the public in that they use the same safety factor to limit whole-body average SARs to 0.08 W/kg and local SARs to 1.6 W/kg. For frequencies below 1.34 MHz, the NCRP limits the power density to 100 mw/cm2, which is higher than the IRPA limit but the same as the ANSI limit. The NCRP does not provide guidance for frequencies below 300 kHz; therefore, their standards do not cover the GWEN LF band. _EPA_ (1986) has Proposed three alternatives for limiting public exposure to RFR. Two alternatives are similar to the other standards: limiting whole-body-average SARs to either 0.4 W/kg or 0.08 W/kg for frequencies above 3 MHz. The third alternative (EPA option 1) is the most restrictive, as it limits whole-body average SARs to 0.04 W/kg for frequencies above 3 MHz. Below 3 MHz this option would limit E-field intensity to 87 V/m and H-field intensity to 0.23 A/m. While this option is more restrictive than the IRPA standard for frequencies greater than 3 MHz, it is equal to the IRPA standards for lower frequencies. The EPA proposal does not specify limits on local SAR values, but it does note that the exposure limit under its option I will substantially reduce local heating effects of RF body currents by keeping the local SAR to less than 4 W/kg. 3.11.4 Approach to Analysis In order to assess possible RFR biological hazards, the pertinent literature on electric shock, radio frequency (RF) burns; and bioeffects related to absorbed energy was reviewed. Findings that might be relevant to GWEN frequencies were evaluated by comparing the RF intensity levels studied to actual measured levels at GWEN facilities. The objective of the analysis was to determine the extent of the zone around an RN's antenna base that would need to be controlled in order to prevent public exposure to RFR levels that exceed safety standards. 3.11.5 Data Sources The present level of knowledge regarding biological effects of RFR was reviewed in an EPA report by Elder and Cahill (1984) and a report prepared for the USAF School of Aerospace Medicine (USAFSAM) by Heynick and Polson (1983). The latter report was updated and expanded by Heynick (1986) and will be reissued. Information is also summarized by Polk and Postow (1986), Elder (1986), and in the EPA announcement of the proposed alternative guidelines for RFR protection (EPA 1986). Two recent reports prepared for USAFSAM document possible hazards in the frequency range of 10 kHz to 3 MHz, which brackets the GWEN LF antenna frequencies (Gandhi et al. 1985; Guy and Chou 1985). 3.11.6 Existing Conditions The potential health effects to humans associated with exposure to RFR can be divided into two major categories: Electric shock and RF burns resulting from contact between grounded people and ungrounded objects. Bare feet on wet ground would provide maximum grounding. Footware (shoes) reduce the level of grounding and provide some measure of protection. The analysis below assumes an individual who would be fully grounded. A wide range of effects resulting from the energy absorbed by the body. 3.11.6.1 Electric Shock and RF Burns Electric shock and RF burns can occur because of voltages induced by RFR below 3 MHz, and particularly below 200 kHz, in ungrounded conductive objects, such as vehicles, fencing, metal roofing, and guy wires. When an individual that is electrically grounded makes contact with an ungrounded conductive object in an RF field, currents may then flow through the individual's body. The amount of current flow depends on how well the individual is electrically grounded, the impedance between the ungrounded object and the individual, and the voltage and charge of the object induced by the RF field. At low-intensity RF fields, a grounded individual might experience a tingling or warm feeling in the fingers, hands, wrists, or ankles when in contact with an ungrounded conductive object. At higher field intensities, an individual might experience an electric shock as contact was made with the ungrounded object. Electric shock can also result when an ungrounded individual in a high-intensity RF field comes into contact with a grounded object. If the flow of current is large enough, it can cause localized heating of body tissue resulting in an RF burn. RF burns can also be caused by direct contact with an RF source (e.g., an antenna) or an uninsulated transmission line. Direct contact with a GWEN antenna is discussed under system safety. Two independent groups of researchers have recently studied the shock hazard from objects in RF fields with frequencies of 10 kHz to 3 MHz (Guy and Chou 1985; Gandhi et al. 1985). The results were based on actual measurements at RF antennae and experimental measurements on several hundred subjects. Since the shock hazard is due to the electric, rather than magnetic, component of RF fields, thresholds were stated in terms of the intensity of the E-field. Perception thresholds corresponded to the mean lowest current (measured in a laboratory experiment) at which the subjects reported any sensation at all, usually mild tingling or pricking at frequencies below 100 kHz and faint warmth at higher frequencies. The pain thresholds corresponded to the mean lowest current at which the subjects reported a very uncomfortable sensation and did not want to continue touching the electrode. Chatterjee et al. (1986) believe that the cause for sensations at frequencies above 100 kHz is an increased energy density, or SAR, in the hand or wrist. For the frequency range of the GWEN LF antenna (150 to 175 kHz), Gandhi et al. (1985) and Chatterjee et al. (1986) calculated perception thresholds for grounded 10-year-old children in finger contact with large ungrounded metallic objects. These thresholds were 65 V/m for a fork-lift truck, 120 V/m for a van, and 250 V/m for a 50-foot section of fence. Calculated perception thresholds for electrically grounded adults touching those objects were about 40 percent higher. Calculated perception and pain thresholds for persons in grasping contact were higher than for persons in finger contact. For example, the perception threshold for a 10-year-old child in grasping contact with a van was 430 V/m, as opposed to 120 V/m for finger contact. However, Chatterjee et al. (1986) report that perception thresholds for a tapping contact with the finger was about 10 percent lower than for continuous finger contact. Also, they report that, for frequencies greater than 100 kHz, a continuous contact at the perception threshold produced a sensation of pain within 10 to 20 seconds. In addition to causing perception or pain, the flow of current through the body could be sufficiently high to produce some damage to tissues. Gandhi et al. (1985) addressed this by calculating the E-field required to produce a whole-body-average SAR of 0.4 W/kg and a local SAR of 8 W/kg of a grounded individual in grasping contact with a van. These SAR values are the limits set by ANSI and are a factor of 10 below those that cause harmful effects. Gandhi et al. determined that, at GWEN frequencies, an E-field of 300 V/m would be required to produce a whole-body-average SAR of 0.4 W/kg, and 95 V/m would be required to produce a local SAR of 8 W/kg in the wrist of a 10-year-old child; these values would be about 40 percent higher for adults. Gandhi et al. (1985) also considered the flow of current through a grounded individual not in contact with a metallic object or in the vicinity of one. They calculate that at GWEN frequencies, the E-field required to produce a whole-body average SAR of 0.4 W/kg would be 9,000 V/m, and the E-field required to produce a maximum local SAR (in the ankle) of 8 W/kg would be 2,000 V/m. These calculations of the E-field intensities required to produce the specific SAR values reported were based on the assumption that the RFR is continuously emitted. When the RFR is not continuously emitted, the SAR values will be lower for the same E-field, or, conversely, the E-field must be higher to produce the same SAR. This is the case for GWEN, which broadcasts with a duty cycle of 28 percent. Since SAR is proportional to the square of the E-field intensity, the continuous E-field values given by Gandhi et al. may be divided by the square root of 0.28 to yield discontinuous E-field values for application to GWEN. Therefore, the GWEN E-field required to produce a local SAR of 8 W/kg in the wrist of a child in grasping contact with the van would be 180 V/m. (This value is well below the perception threshold for a child in grasping contact.) The GWEN E-field required to produce a local SAR of 8 W/kg in the ankle of an adult not in contact with a metallic object would be 3,780 V/m. The GWEN E-field required to produce the IRPA limit of 0.8 W/kg for a local SAR would be 1,195 V/m. 3.11.6.2 Effects Due to Absorbed Energy The other major category of potential health effects is associated with energy absorbed by the body when exposed to RFR. Generally, energy absorption is related to frequency. When frequency is such that the incident wavelength is much smaller than the size of the exposed subject, there is poor penetration and energy is deposited largely on the surface of the subject (Cahill and Elder 1984; Polk and Postow 1986). For humans, that corresponds to frequencies greater than about 5,000 MHz. When the incident wavelength and the subject are the same order of magnitude, resonance occurs and maximum energy is absorbed. The resonant frequency varies depending on thc size of the human body and ranges from about 35 MHz for a grounded adult 5 feet 9 inches tall to about 200 MHz for an ungrounded infant. When the wavelength is much greater than the subject's size, the absorptive coupling is inefficient and little energy is absorbed. This occurs in humans at frequencies lower than about 1 MHz, and includes the GWEN LF frequency (150 to 175 kHz) with wavelengths about 1,000 times greater than the size of humans. RFR from the GWEN UHF antennae (/25 to 400 Mhz) falls in a range just above resonant frequencies (see section 4.11.1.2). The accepted measure of RF absorption is the SAR, which is the mass-normalized rate of energy absorption in watts per kilogram (W/kg). The SAR depends on the dielectric composition and shape of the subject, its orientation with respect to the RF field, and the complexity of the radiation, as well as on the size of the subject relative to the wavelength. The SAR can be estimated by combining the frequency and power density of the RF field with the size and dielectric property of the subject exposed to the field (Cahill and Elder 1984). Such calculations can be performed for humans exposed to the RFR from GWEN. For an average man, the _Radio_Frequency_Radiation_Dosimetry_Handbook_ (Durney et al. 1978) indicates that the maximum average SAR at the GWEN LF band would be approximately 0.0000006 W/kg per 1 mW/cm2, occurring when the long axis of the body was parallel to the E-field polarization. When the body was perpendicular to the E-field, the average SAR would decrease by a factor of approximately 30. The maximum value of the E-field from the GWEN LF transmitter outside the 4-foot fence would be 50 V/m (see section 4.11.1.1). This is equivalent to approximately 0.66 mw/cm2 (assuming a plane wave). Therefore, the maximum average SAR in a human standing in an E-field of intensity 50 V/m would be approximately 0.0000004 W/kg, assuming continuous RF emission. Since GWEN broadcasts LF transmissions with a 28-percent duty cycle, the maximum average SAR at the 4-foot fence would be approximately 0.0000001 W/kg. The maximum average SAR associated with GWEN UHF exposure can be calculated in a similar fashion. At the frequency band used for GWEN UHF transmissions, the maximum average SAR would be 0.1 W/kg per 1 mW/cm2 (Durney et al. 1978). Since the maximum exposure to GWEN UHF would be 0.001 mW/cm2 for a 40 percent duty cycle (see section 4.11.1.2), the maximum average SAR at a GWEN station due to UHF exposure would be 0.0001 W/kg. A number of so-called "nonthermal" effects have been described in the scientific literature in connection with RFR exposure of laboratory animals and animal tissue at levels equal to or less than 0.4 W/kg (EPA 1986). These effects, involving the cellular, hematologic, reproductive, nervous systems, and others, are summarized in a review by Cahill and Elder (1984). The significance of these effects for public health is not clear, partly because the mechanisms responsible for them are not known. Some results are from single studies and have not yet been verified by duplication (EPA 1986). In some cases, there are conflicting results as to whether a given effect even occurs. At this time, it is not yet clear whether low-level nonthermal effects have an impact on human health. Consequently, the EPA (1986) concludes that the data are insufficient to assess the adversity and human health implications of effects observed for whole-body average SAR below 1 W/kg. However, in light of the SAR values for humans exposed to RFR from GWEN (less than 0.0000001 W/kg for LF and 0.0001 W/kg for UHF), nonthermal effects are extremely unlikely. A degree of uncertainty exists in extrapolating findings on animals to humans because of differences in species, exposure frequencies, and internal distribution of absorbed energy (Heynick and Polson 1983; Heynick 1986). There is very little information on RF effects in humans and limited data on responses of animals at frequencies above 10 GHz and below 10 MHz. However, the use of SAR as an index of exposure has allowed excellent extrapolation of effects across frequencies, and it is reasonable to assume that would also be applicable for GWEN frequencies. The health effects related to exposure to RFR have been the subject of continuing research for about 30 years, and an estimated 8,000 papers on RFR bioeffects have been published. Over the past decade great advances have been made in correlating the observation of effects (or lack thereof) with the SAR. Although SAR is associated with energy deposition, and frequently only with thermalization of the RFR energy in tissue, it also defines the fields existing within the tissues, and is a useful measure when discussing both thermal and nonthermal effects. Research papers cover a wide range of general topics in the biological sciences. These include epidemiologic studies of humans; the possibility of RFR exposure causing cancer or birth defects, effects on the eye, the nervous system, behavior, hormone-secreting systems in mammals, and the immune system; and general biochemical and physiological effects (Heynick and Polson 1986; Heynick 1986; Polk and Postow 1986). The interested reader is referred to these publications for more specific details of representative papers under each biological topic. The following discussions summarize those reviews. The discussion of effects due to absorbed energy is in reference to RFR in general. Most of the studies were at UHF and, therefore, would be applicable to GWEN UHF exposure. The SAR for GWEN exposure would be several orders of magnitude below the SARs associated with any reported effects. Therefore, it would be very unlikely that these effects would result from GWEN UHF exposure. Although none of the studies were conducted at LF, assessment of GWEN LF exposure can be made by comparing the GWEN SAR with the SARs reported in the studies. Since GWEN LF exposure would be many orders of magnitude below SARs associated with reported effects, the possibility that there would be any effects would be very remote. _Epidemiologic_Studies_. Although there are relatively few epidemiologic studies, those that have been performed have included several hundreds of thousands of individuals. None of the studies offers clear evidence of detrimental effects associated with exposure of the general population to RFR. However, findings of studies performed in the Soviet Union suggest that occupational exposure to UHF RFR at average power densities of less than 1 mw/cm2 does result in various symptoms (which they lump together as "microwave syndrome") but this is generally not recognized in western medical practice. The SARs associated with GWEN LF exposure, at frequencies 1,000 to 10,000 times lower than UHF, would be many orders of magnitude lower. Thus, even if one accepted the Soviet findings for UHF frequencies, the likelihood of such effects at GWEN frequencies and power intensities is remote. Collectively, the results of the epidemiologic studies do not provide evidence of the likelihood of any hazard to the general population from exposure to RFR from GWEN. Exposure to GWEN UHF would be at power densities of 0.001 mW/cm2 or less (see section 4.11.1.2) which would be two to three orders of magnitude below the power densities of the observations in the Soviet studies. _Cancer_. One frequently expressed concern about RFR is that it may cause mutations or cancer. Several studies regarding the possible mutagenic effects of RFR have been done on bacteria, yeast, and fruit flies. These studies failed to demonstrate mutagenic effects that could be attributed to RFR exposure. Other studies using mice and rats also have failed to provide evidence of mutagenic effects. Studies on the general health or the occurrence of cancer in exposed animals have generally yielded negative results. Extrapolation of these animal studies to humans indicates that the SAR associated with human exposure to GWEN RFR is most unlikely to cause mutagenic effects or to cause cancer. _Birth_Defects_. Birth defects (technically, teratogenesis) and developmental abnormalities after birth are always of public concern, especially because, in a few cases, specific (non-RFR) agents have been shown to cause such effects. Birth defects and developmental abnormalities also occur naturally at a low rate in most animal species. Teratogenuc studies associated with RFR have used a variety of animal models. The results indicate that a threshold of heat induction or temperature increase must be exceeded before teratogenic effects are produced. For the SARs associated with human exposure to GWEN RFR, there would be no detectable heating, so birth defects would be extremely unlikely. _Cataracts_. It has been asserted in newspapers and other popular media that microwaves potentially cause cataracts. Scientific studies have indicated that microwaves can cause cataracts in experimental animals, but only if incident continuous-wave power densities are high, approximately 150 mw/cm2 or greater. Under such conditions of frequency and power density, local SARs in the eye can be so great that significant temperature rises occur. Such effects also appear to have a threshold; if a critical temperature is not exceeded within the eye for a certain duration, no cataracts are formed. Recent studies also indicate effects on corneal endothelium in the eyes of monkeys exposed to microwaves, but there is no evidence that such effects could occur at SARs associated with exposure to GWEN RFR. _Nervous_System_Effects_. Several types of studies have been conducted regarding the effects of RFR on the nervous system of animals. U.S. scientists consider most effects of RFR on the nervous system to be indirect results of other physiological interactions, with the possible exception of alterations of calcium-ion binding in brain tissue. This phenomenon occurs with amplitude-modulated waveforms for a wide range of carrier frequencies from extremely low frequency to UHF. However, there is no evidence that it occurs at power densities below 0.1 mw/cm2, and even if it did, there is no indication that it is in any way associated with adverse health effects. Other observed nervous-system effects have included: alteration of the permeability of the blood-brain barrier, but consistent data exist only for local SARs that are sufficient to cause heating; alterations in and damage to some regions of the brains of hamsters and rats (but not of squirrel monkeys), but, again, resulting from thermal processes; and alterations of electroencephalograms (electrical activity of the brain) in animals, but only when in-dwelling electrodes were used. The last effect is the only one that could perhaps apply to the GWEN system. With modern advances in medical technology, it is becoming more common (though still rare in terms of absolute numbers) for patients with certain neurological problems to have metal electrodes implanted in their brains. Such persons could be affected by fields within the immediate vicinity of the GWEN transmitters. However, there are no known reports of anyone having been affected by RFR as a result of any surgical implantation to correct neurological problems. All other effects on the nervous system are unlikely to occur at the SARs associated with human exposure to GWEN RFR. _Behavioral_Effects_. Many experimental studies have been conducted on the effects of RFR on animal behavior. The results of such studies are considered particularly important in the Soviet Union, where they are often held to be evidence of direct effects of RFR on the central nervous system (CNS). U.S. scientists do not always agree that behavioral effects necessarily imply direct effects on the CNS. However, as behavioral effects are very sensitive indicators of biological function, they receive appropriate attention in both eastern European and western countries. Representative behavioral studies (Heynick and Polson 1986; Heynick 1986) include studies of effects on reflex activity, RFR perception, effects of RFR on learning and on performance of trained tasks, interactive effects of RFR and drugs on behavior, and behavioral thermoregulation. Studies have been conducted on mice, rats, rabbits, squirrel monkeys, rhesus monkeys, and humans. Soviet claims of effects at low-power densities (equal to or less than 0.5 mw/cm2) for long-term exposures have not been duplicated in similar studies by U.S. researchers. The validity of the Soviet claims is difficult to assess because of lack of detail in the reports of the experiments. It is very likely that behavioral effects could have been seen if in-dwelling electrodes were used for the animals involved in the Soviet studies, but it is unknown whether they were. RFR is capable of producing alterations in a wide variety of behaviors of various animals. Except for pulsed RFR, average power densities required to modify behavior are almost all at levels of approximately 5 mw/cm2 and above, with corresponding SARs of approximately 1 W/kg and above. Perception of pulsed RFR (i.e., microwave hearing) is a peak-power phenomenon, not an average-power one, and can thereby modify behavior. It is difficult to relate most of the behavioral studies in animals to humans. All behavioral studies are directly relevant to the nature of the species being studied, and the conclusions of a given study do not readily transfer to other species. Because the SARs needed to cause reported effects are so high, these studies provide no evidence that exposure to RFR at the levels that would be emitted outside the fence at GWEN RNs would likely have adverse effects on human behavior. _Endocrine_System_Effects_. Exposure of animals to RFR has produced somewhat inconsistent effects on the hormone-secreting (endocrine) system of mammals. In general, the effects appear to be related to either the heat load associated with the RFR or the stress induced in the animals by the RFR or, possibly, other experimental circumstances. Some effects also appear to be related to alteration of the circadian rhythm by RFR. There do not appear to be any effects clearly demonstrated to be associated with nonthermogenic stimulation of the endocrine system or the associated parts of the CNS. Because the reported effects of RFR on the endocrine systems of animals are largely ascribable to increased thermal burdens and stresses engendered by the experimental situation, there is no evidence that such effects would occur in humans exposed to the RFR from the GWEN transmitter outside the fence because of the extremely low SARs involved. _Immune_System_Effects_. The accumulation of reports to date indicates that RFR has definite effects on the immune system of mammals. Most of the reported effects were detected after exposure at SARs about 4 W/kg and higher; a few have been detected following exposure at SARs as low as 0.2 W/kg. In some cases, the effects that were observed at higher power densities were not found at lower power densities, indicating the possibility of a threshold power density. In most studies, the mechanisms for the effects seen were not investigated, and the various reports are somewhat inconsistent. The situation is complicated by the complexity of the immune system and the variety of test procedures used. The existing evidence indicates that some of the immune-system effects are probably related to the effect of RFR on the endocrine system resulting from adaptation to stress. The mechanisms and significance of such effects are not yet understood, and individual findings have not been independently verified. There is currently no evidence that relates RFR effects on animals' immune systems to effects on the immune system of humans chronically exposed to the levels of RFR that would be experienced outside thc fenced area of a GWEN RN. In addition, because of the extremely small SARs involved, there is no evidence to suggest that such effects would be hazardous to human health. _Biochemical_and_Physiological_Effects_. The literature on biochemical and physiological effects associated with RFR is extensive. Many of the reported effects are associated with other events (e.g., changes in hormonal levels or stress adaptation), and some do not have clear medical significance. The thermal basis for most of the reported physiological and biochemical effects of exposure of intact animals to RFR is evident. The investigations with nonhuman primates are most significant with respect to possible hazards of human exposure to RFR because the anatomies and physiological characteristics of primates are closest to those of humans. The results with rhesus monkeys showed that exposure to RFR at frequencies in the range of 3 to 30 MHz at average-power densities of about 100 mw/cm2 were well within the thermoregulatory capabilities of this species. Also noteworthy were the negative findings of blood-chemistry assays performed on rhesus monkeys one to two years after exposures to such high-power densities. The thermoregulatory system of squirrel monkeys were also observed to effectively compensate for RFR exposure. The investigations involving exposure of intact, smaller species of mammals to RFR have yielded both positive and negative results. Some of the positive findings are also clearly due to the additional thermal burden posed by the RFR. Other results, showing decreased food intake and lower blood glucose levels in rats, indicate the existence of a SAR threshold of about 1 W/kg or higher for such effects. One physiological concern is whether exposure of humans to RFR can affect their heart function. In early work on this subject with excised turtle, frog, and rat hearts, various investigators reported RFR-induced decreases and/or increases in heart rate, depending on average power densities. Decreases in heart rate were reported for the lower range of power densities used. The lowest SAR at which heart rate decreases were observed in the isolated turtle heart was 1.5 W/kg. Some recent work showed no RFR-induced changes in beat rate or contractile force in isolated atria of rat hearts exposed to 2.45 GHz RFR at 2 or 10 W/kg. SAR-dependent changes in heart-beat rate in intact animals were also reported. The results indicate the existence of a threshold between 4.5 and 6.5 W/kg, many orders of magnitude higher than could occur outside the fence of a GWEN RN. Thus, in general, it is very improbable that physiological or biochemical effects would occur from exposure to RFR from GWEN transmitters at the levels that would be experienced outside the fenced area of an RN. _Conclusion_. Most U.S. experiments with animals that yielded recognizable and repeatable effects of exposure to RFR were performed at whole-body average SARs of more than about 1 watt per kilogram (W/kg). Such effects are thermal, in the sense that the RFR energy is absorbed by the organism as widely distributed heat that increases the whole-body temperature, or as internally localized heat that is biologically significant even when natural heat-exchange and thermoregulatory mechanisms are functioning. The existence of threshold incident average power densities has been experimentally demonstrated for some effects and postulated for others. Exposure to RFR at average power densities exceeding the threshold for a specific effect for a few minutes to a few hours (depending on the value) can cause irreversible tissue alterations. The heat produced by indefinitely long or chronic exposures at power densities well below the threshold is not accumulated because its rate of production is readily compensated for by either heat-exchange processes, thermoregulation, or both. Most investigations involving chronic exposures of mammals yielded either no effects or reversible, noncumulative behavioral or physiological effects for average power densities exceeding whole-body SARs of 1 W/kg. In the few cases in which irreversible adverse effects of exposure were found, these effects were absent for whole-body SARs below 1 W/kg. Whole-body SARs resulting from exposure to RFR at a GWEN RN would be below 0.0000001 W/kg outside of the 4-foot circular fence.