High Levels of RF Radiation

Thermal vs. Athermal

The difference between thermal and athermal effects is if the body temperature is measured to be below an arbitrary, finite temperature change (usually 1°C), then the effect is assumed to be athermal. An effect could also be considered athermal i f the same effect is not found when the ambient temperature is used to increase the body temperature the same amount {1}.

There is difficulty in determining whether an observed biological effect is due to thermal, athermal, or a combination of both effects. In particular, biological/behavioral responses do not indicate a method of interaction. As an example, imagine the following, in which the scientist would like to determine the cause of the behavioral response: a man touches a hot frying pan and immediately jumps back and runs to run his hand under cold water. The behavioral re sponse is fairly dramatic, but what caused it? If we were to measure the temperature of the body, we would notice no increase. Thermal effects are by name those which cause an increase in body temperature. With no knowledge of the nature of the stimulus, we would conclude that the man's response was due to an athermal effect. This simple example only serves to show the great uncertainties and possibilities for error involved in studies of RF radiation. For this reason, division of biological effects of RF/EM fields into thermal and athermal categories should not be based on whether a temperature increase can be measured. The increase may be too slight to measure, and living bodies have thermoregulation systems that will compensate for increases so it won't necessarily be apparent that they're there. For these reasons a clear distinction needs to be made between whether the biological response is because of heating or direct interaction.

There are many problems with much of the literature on biological effects of radiofrequency radiation. Many of the experiments have not been reproduced, and some of those that have been reproduced showed contradictory results (but there is always the question of how similar the experiments are). There is even a question of the laboratory having a "culture of vigorous science." This all leads to frustrations in those conducting risk analyses {1}.

Humans have not been used in many experiments, because of the obvious risks. Instead, most studies have used animals, which then requires interspecies scaling to determine effects on humans. Even if an animals absorption patterns are similar to huma ns, there is the issue of physical and physiological dissimilarities. It is difficult to extrapolate from effects on animals to those on humans, especially because of differences in body geometry, internal vascal anatomy, and mechanisms of heat dissipati on (especially between fur-bearing mammals and humans). An effort must be made to make conditions as relevant as possible. There needs to be a standardization of conditions, but they are not always obtained {1}.

Is there evidence that the radio frequency radiation from cellular or PCS phone systems causes biological effects?

Does radiofrequency radiation affect human reproduction?

There is no evidence that at the exposure levels produced by cellular and PCS phone systems that there is any effects on human reproductive processes. Even though most studies have been done at frequencies greater than 2.45 GHz, well above the frequen cy of PCS or cellular, there is general agreement that only high power densities (greater than 50 mW/cm^2) can affect testes and ovaries. But this is still much greater than exposure levels allowed by FCC regulations. Some chronic "low-level" exposures (5 mW/cm^2, which is much greater than that PCS or cellular phone systems) at 27 MHz and 2.45 GHz have been shown to impair formation of sperm and reproductive functions, such as significant reduction in the ability of the irradiated sperm to fertilize (o r penetrate) the ova, without measurable temperature differences in the testes. This was shown to be a direct, not thermal, effect [1].

Does radiofrequency radiation affect the growth and development of a fetus?

Indirectly, radiofrequency radiation can cause birth defects and miscarriages, but only at exposure levels high enough to heat the whole body of the mother, but this will not occur at levels the general public is exposed to from PCS and cellular phone s or antennas [2]. It is only with high level, acute exposures, that cause a 2.5 to 5 degree body temperature increase, that birth defects can result from through hyperthermia. A temperature rise in the fetus, however, no matter what the heat source, wi ll cause this damage. No serious effects have been found from radiofrequency radiation at less than 10 mW/cm^2, which is not experienced by the public [1]. There seems to be a threshold in maternal body temperature, only above which is there any damage done [7]. Power levels from cellular phone and PCS antennas are too low to cause this heating and there is no evidence, laboratory or epidemiological, that these low power levels contribute to birth defects or miscarriages [2].

Several reports have shown that particular combinations of frequency, duration and intensity of exposure can have effects on embryonic development and postnatal growth in insects, chick embryos, and rodents. Mammalian studies have mostly dealt with a cute exposure on embryos or fetuses at power densities that increase the body temperature. Only a few studies looked at the effects of protracted exposure with insignificant change in body temperature. Teratogenic studies (relating to malformations of e mbryo or fetus) tend to be "more diverse than decisive" in respect to their basic design, procedure and variables assessed. There is great variation in exposure parameters, and many reports do not include information on critical variables (e.g. how day o f gestation was timed). Often the treatment of control animals is not discussed in reports making comparisons with other studies difficult. Multiple controls are not always used, and many studies do not use enough subjects [1]. Aside from this, trends in results show that fetal exposure to radiofrequency radiation radiation at power levels high enough to increase the body temperature significantly results in the nonspecific, general response of reduced/retarded gain in body mass, there is no other spec ific abnormality in a specific organ system [8]. It is not evident if this continues after birth or if a stunted fetus ever catches up. This loss of body mass in fetuses is the only effect that was consistently found through the literature, but these ar e similar to heat stress effects caused by other sources [1].

Does radiofrequency radiation cause DNA damage?

No, DNA damage has not been demonstrated as a result of exposure levels within the FCC standards. Many studies have been conducted on the genotoxicity of radiofrequency radiation and it has been found that the biological effects from exposure are ver y frequency dependent. There has been evidence of some chromosomal changes in various plants and animal cells in tissue culture, but this is at exposures between 7 mW/cm^2 and 200 mW/cm^2, which are much higher exposure levels than the general public wil l come into contact with. These experiments were poorly documented and have not been replicated, however, so there is little confidence in their validity [1]. A few studies have found mutations in mammals after exposure to radiofrequency radiation, but t hey are critically doubted. The lowest exposure level of these possible cytogenetic effects was 20 mW/cm^2 (but even this was questioned in a later report) [1]. The most relevant study of the effects of radiofrequency radiation from cellular or PCS ante nnas is from Meltz et al (1987,1990). Using a variety of frequencies, 350, 850, 1200, and 2450 MHz, at up to 40 W/kg SAR, there was no evidence of genotoxicity or interference with the natural repair of DNA when damaged by chemical and physical mutagens [9].

Do radiofrequency radiation have effects on the nervous system?

There is no evidence that radiofrequency radiation at the exposure levels produced by PCS and cellular phone or antennas has effects on the nervous system. Radiofrequency radiation can cause transient effects in the central nervous system, but it is not clear from the literature whether or not they are thermal. Cellular changes in the central nervous system have been witnessed in small animals from exposures to radiofrequency radiation at 10 mW/cm^2. Even so, many reports have differing results, par tially due to differences in the geometry of animal heads, exposure methods, daily exposure duration, variations in gestation periods and species differences [1].

There have been some reports of radiofrequency radiation causing alterations in electroencephalographic (EEG), but there are deficiencies in methodology and interpretation in the literature. The EEG is difficult to quantitate, because it is a time-va rying wave form. Also, metal electrodes, whether implanted in the brain or attached to the scalp to measure the effects of radiofrequency radiation can lead to questionable reports. They greatly disturb the field, enhancing the absorption of energy near the electrode [1]. There is no credible evidence that at low exposures to radiofrequency radiation have an effect on the EEG [7].

The Blood Brain Barrier (BBB) normally provides resistance to movements of large-molecular-weight, fat-insoluble substances (such as proteins and polypeptides) from blood vessels into cerebral extracellular fluid. This protects the brain from blood-b orne pathogens and toxic substances. Some early research showed that radiofrequency radiation can make the BBB more permeable, leaving the brain more susceptible, but others have been unable to confirm these findings. It is possible that the methodology used in the early experiments was to blame or that results were interpreted differently, both of which are common issues in research of this region. Another problem is that different substances are subject to different mechanisms of transport, including simple diffusion, facilitated diffusion, active transport, and vesicular transport, so comparisons become difficult. Changes in temperature also have large effects on some processes. The intrinsic permeability is often indiscernible from these other fac tors [1]. At low level exposures, recent, conclusive research has not found any effects on the BBB [7].

Researchers who follow a pharmacodynamic approach have noticed that exposure to radiofrequency radiation before neurotropic drug doses can alter the sensitivity of the drug, but only at exposure levels that significantly increase the body temperature. This can lead to an increase or decrease in sensitivity, depending on the drug. Warming animals with radiofrequency radiation during anesthesia, for example, attenuates the effects of Phenobarbital. In some cases, the drugs and radiation have parallel effects, so there may be a common mechanism. The role of local absorption patterns are important [1]. It is not likely that the effects of prescribed psychoactive drugs or from recreational use of alcohol can be affected by low exposures to radiofreque ncy radiation [7].

Does radiofrequency radiation have effects on behavior?

No negative effects on behavior have been found after exposure to radiofrequency radiation at levels within the FCC regulations for PCS and cellular phones and antennas. There is a power density/dose threshold, which depends on the duration of exposur e and other parameters. This threshold has been found to be no lower than 4 W/kg (causing approximately a 1'C increase in body temperature) which is well above exposure levels produced by cellular and PCS phone systems [8]. The effects of radiofrequency radiation on the performance of trained tasks or operant behavior of rats, rheirs, and squirrel monkeys have been studied. In all of the studies, exposures resulted in the suppressed performance of a trained task. The most relevant studies are those th at involve primates, because the trained skills they learn are more complex, and their physiology and intelligence is closer to our own. It is the thresholds found in these studies that are the basis for the ANSI/IEEE standards [7]. Heating, in general, not only from radiofrequency radiation, also has a general debilitating effect, causing a decreased motivation for food in rats [1]. Although the mechanisms of how the radiofrequency radiation affect behavior are unclear, alterations in behavior were fo und to be reversible, and behavior went back to normal after exposure [4].

Behavior, in general, reflects adaptive brain-behavior patterns. It becomes important in the research of effects of radiofrequency radiation, especially in reference to behavioral thermoregulation[link to Tina's info on thermoregulation], the conscio us attempt to maintain a constant body temperature [1].

neuro

Are there any neuroendocrine effects from radiofrequency radiation?

The only affects on the neuroendocrine system were found at exposure levels higher than those produced by cellular or PCS phone systems. The function of the neuroendocrine system is to maintain homeostasis in the body. Most studies of rat endocrine systems include whole body radiofrequency exposures in search of the level of organization of the system at which the effect is exerted and the nature of that effect. The effects of radiofrequency radiation on the endocrine system are consistent with the immediate and long term responses to thermal and nonspecific stress. There are some reports of biochemical and physiological changes from radiofrequency radiation exposure, which suggests an adrenal effect. The evidence is consistent with the hypothesis that stimulation of the adrenal axis in rats exposed to radiofrequency radiation is a systemic, integrative process due to general hyperthermia [1].

Some of the effects of radiofrequency radiation on the endocrine system appear to be relatively straightforward physiologically, but there are other effects that are more subtle, and will require more study (especially interactions among pituitary, ad renal, thyroid, hypothalamus, and or their secretions). It is often difficult to interpret the results of research because of the uncertainty of stressors that may be inadvertently introduced. This is especially the case when an animal is placed in a ne w environment, leaving it prone to stress responses [1].

Do radiofrequency radiation affect the cardiovascular system?

There is no conclusive evidence of effects from radiofrequency radiation in the frequency of PCS and cellular at the exposure levels allowed by the FCC on the cardiovascular system. In the former Soviet Union, "microwave radiation" caused by chronic occupational exposure to low levels of radiofrequency radiation was studied, but this research was not well documented or well-defined [1]. Some other effects, such as bradycardia or tachycardia, have been found in different studies with different animal s, but there are inconsistent results on the same animals. Those effects found were reversible [5]. Some of these results may be from natural biologic variability among animals or numerous other sources. Distinctions between thermal and athermal effects are unclear, because a change in body temperature of less than 1'C, if at the right body part, could affect the dynamics of blood [1]. One decisive study found no significant changes in heart rate or blood pressure of humans after an MRI (Magnetic Reson ance Imaging, which in addition to radiofrequency radiation, includes static and time-varying magnetic fields) at whole body SAR up to 1.2 W/kg. Researchers calculated that at an SAR of 2 W/kg would elevate the heart rate by 3%, compared to a 30% increas e by simply eating. Toler et al exposed rats to 435 MHz at SARs between 0.04 and 0.4 W/kg for 22 hours a day, seven days a week for six months. After this low level, long term exposure, found no significant difference in heart rate and blood pressure be tween those exposed and control animals [10]. No conclusive cardiovascular hazards have been found after exposure to low level radiofrequency radiation such as would be the case with cellular or PCS phones [5].

Do radiofrequency radiation have effects on immune response?

There have been no conclusive negative effects on the immune system found due to the exposure to radiofrequency radiation from PCS and cellular phones or antennas. Actually, this radiofrequency radiation can help to enhance the response of the immune system. The immune system plays an important role in homeostasis in the body by detecting and responding to foreign molecules and neoplastic cells through complex molecular and cellular interactions [3]. In the early 1980s, research on the effects of r adiation on the immune system focused on enhancing immune response with radiofrequency radiation exposure for therapeutic applications. This was until studies shifted with the ELF (extremely low frequency) controversy [1].

Most, if not all, of the responses of the immune system to radiofrequency radiation was in response to heat. When power densities are low enough that the body can regulate the temperature, there were no consistent responses [3].

Lymphocytes are immunologically distinct populations that can grow in size quickly when stimulated in a process called lymphoblastoid transformation. It is difficult to compare reports and analyze literature due to extrapolations between in vitro and in vivo effects that are necessary [1].

Physiological adaptations or decreased reactions as a result of repeated exposures to radiofrequency radiation have been reported. Animals adapted to the presence of radiofrequency radiation after a period of reactions to it. It appears that radiofr equency radiation initially causes a general stimulation of the immune system, but after continued exposure this stimulating effect disappears. The initial period of stimulation seems to be a phase of adaptation. If radiofrequency radiation do increase the proportion of lymphocytes undergoing transformation, this would not be harmful, but beneficial [1].

Do radiofrequency radiation cause cataracts and is there a cumulative effect on the eye after multiple or long-term exposures?

No cataracts have only been shown to result from radiofrequency radiation at exposures ordered of magnitude higher than are produced by cellular or PCS phone systems. Studies have been done on the development of cataracts and the effects of radiofreq uency radiation on the process, and have found that any effects produced are grossly thermal. There is an apparent time-power threshold, where a higher exposure level would have a lower time threshold. The lowest threshold, according to Guy et al, was f ound to be an average power density of 15 mW/cm^2 over 100 minutes [11]. There are reports of decreased enzyme activity due to the thermal inactivity with resultant changes in metabolism. The first biochemical sign of opacity formation is the decrease i n ascorbic acid concentration on the lens. All of the effects are reparable until the altered metabolism leads to permanent opacity of the lens. The latent period and time-power threshold are consistent with this mechanism [1].

There is a theory that after repeated "sub-threshold" exposures to radiofrequency radiation radiation, there is a cumulative effect of damage (i.e. adding up clinically inapparent damage). This has not been shown in research. The thresholds are well above safety standards and in animal studies, radiofrequency cataractogenesis is a gross thermal effect with a threshold exposure level. During the past thirty years, most of this research has been done on rabbits, and trends have been found. If the t emperature in the eye is raised to 43'C, acute thermal damage results and there is no apparent cumulative effect unless each exposure causes irreparable damage. It is extremely difficult to extrapolate to humans due to differences in conditions, duration , and intensity of exposure. Reports for humans are uncontrolled and exposure conditions are impossible to determine or reconstruct [1].

Can radiofrequency radiation from your PCS or cellular phone interact with a pacemaker?

Within the FCC standards of uncontrolled exposure, the cellular and PCS antenna radiation will not interfere with pacemakers. A PCS phone itself may interfere with a pacemaker if located directly above the heart (within 8 inches), but this will only occur with certain models of phones and pacemakers [2].

Are there certain age groups that are more sensitive to radiofrequency radiation effects?

It is possible that some groups within a population (such as elderly or infants) could be more sensitive to the effects of radiofrequency radiation, but no such groups have been identified. The possibility of this sensitivity is one reason why there is a five-fold margin of safety added to the federal exposure standards [2].

References
[1] Polk, Charles and Elliot Postow, ed. Handbook of Biological Effects of Electromagnetic Fields. New York: CRC Press, 1996.

[2] Moulder, Dr. John. "Cellular Phone Antennas and Human Health - FAQ" (Professor of Radiation Oncology, Radiology and Pharmacology/Toxicology at the Medical College of Wisconsin), developed under a contract with the City of Brookfield, Wisconsin. Febr uary 6, 1997

[3] Carlo, George L.; Sund, Kelly G.; Embrey, Martha. "What can Human and Animal Studies Tell us About Potential Health Risks from Wireless Communication Technology?" Wireless Technology Research, L.L.C., Washington, DC, 1994.

[4] D'Andrea, John A. "Effects of Microwave Radiation Exposure on Behavioral Performance in Nonhuman Primates," Radiofrequency Standards. New York: Plenum Press, 1994.

[5] Jauchem, James R. "Cardiovascular Responses to Radiofrequency Radiation," Radiofrequency Standards. New York: Plenum Press, 1994.

[6] Stuchly, Maria A. "Evaluation of Electromagnetic Fields in Biology and Medicine," Radiofrequency Standards. New York: Plenum Press, 1994.

[7] Polson, Peter and Louis N. Heynick. "Overview of the Radiofrequency Radiation (RFR) Bioeffects Database," Radiofrequency Standards. New York: Plenum Press, 1994.

[8] Gandhi, Om P. Biological Effects and Medical Applications of Electromagnetic Energy. Englewood Cliffs, New Jersey: Prentice Hall, 1990.

[9] Meltz M, Holahan PK, Smith ST, Kerbacher JJ, Ciaravino V. "Interaction of ionizing radiation, genetically active chemicals, and radiofrequency radiation in human and rodent cells." 1990. USA School of Aerospace Medicine, Human Systems Division (AFSC) , Brooks Air Force Base, TX.

[10] Toler, J., V. Popovic, S. Bonasera, P. Popovic, C. Honeycutt, and D. Sgoutas. "Long-term study of 435 MHz radio-frequency radiation on blood-borne end points in cannulated rats. Part II." J. Microwave Power Electromagnetic Energy. 23:105-136, (1988).

[11] Guy, A.W., J.C. Lin, P.O. Kramer, and A.F. Emery, "Effect of 2450-MHz radiation on the rabbit eye," IEEE Trans. Microwave Theory Tech. Vol. 23, No. 6, pp. 492-498 (1975).