Paper for the Scientific Workshop “EMF-Scientific and legal Issues, Theory and Evidence of EMF Biological and Health Effects” in Catania, Sicily, Italy, September 13-14, 2002, organized by the Italian National Institute for Prevention and Work Safety.

BIOLOGICAL EFFECTS OF RADIOFREQUENCY RADIATION

Henry Lai
Department of Bioengineering
University of Washington
Seattle, WA
USA

There is no question that radiofrequency radiation (RFR) affects functions in cells and living organisms. One important determinant of effects is the amount of energy deposited in or absorbed by the exposed object. In addition, there are some indications that biological effects may also depend on how the energy is deposited. Different propagation characteristics such as ‘modulation,’ or different waveforms and shapes may have different effects on a living system. Different biological effects may result depending on the intensity, waveform, and duration of the exposure.

Biological effects can occur after exposure to high intensity of RFR that can cause general or local heating. However, effects have also been reported in cells and animals after exposures to very low-intensity RFR that apparently cannot cause a significant change in temperature. The following is a list of these studies. (Some studies only give the power density, in mW/cm2, of the radiation, whereas others give the specific absorption rate (SAR), in W/kg, in the exposed objects).

(1) Balode (1996)- blood cells from cows from a farm close and in front of a radar showed significantly higher level of severe genetic damage.
(2) Boscol et al. (2001)- RFR from radio transmission stations (0.005 mW/cm2) affects immunological system in women.
(3) Chiang et al. (1989)- people lived and worked near radio antennae and radar installations showed deficits in psychological and short-term memory tests.
(4) De Pomerai et al. (2000, 2002) reported an increase in a molecular stress response in cells after exposure to a RFR at a SAR of 0.001 W/kg. This stress response is a basic biological process that is present in almost all animals - including humans.
(5) D'Inzeo et al. (1988)- very low intensity RFR (0.0020.004 mW/cm2) affects the operation of acetylcholine-related ion-channels in cells. These channels play important roles in physiological and behavioral functions.
(6) Dolk et al. (1997)- a significant increase in adult leukemias was found in residence who lived near the Sutton Coldfield television and frequency-modulation (FM) radio transmitter in England.
(7) Dutta et al. (1989) reported an increase in calcium efflux in cells after exposure to RFR at 0.005 W/kg. Calcium is an important component of normal cellular functions.
(8) Fesenko et al. (1999) reported a change in immunological functions in mice after exposure to RFR at a power density of 0.001 mW/cm2.
(9) Hjollund et al. (1997)- sperm counts of Danish military personnel, who operated mobile ground-to-air missile units that use several RFR emitting radar systems (maximal mean exposure 0.01 mW/cm2), were significantly low compared to references.
(10) Hocking et al. (1996)- an association was found between increased childhood leukemia incidence and mortality and proximity to TV towers.
(11) Ivaschuk et al. (1999)- short-term exposure to cellular phone RFR of very low SAR (26 mW/kg) affected a gene related to cancer.
(12) Kolodynski and Kolodynska (1996)- school Children lived in front of a radio station had less developed memory and attention, their reaction time was slower, and their neuromuscular apparatus endurance was decreased.
(13) Kwee et al. (2001)- 20 minutes of cell phone RFR exposure at 0.0021 W/kg increased stress protein in human cells.
(14) Lebedeva et al. (2000)- brain wave activation was observed in human subjects exposed to cellular phone RFR at 0.06 mW/cm2.
(15) Magras and Xenos (1999) reported a decrease in reproductive function in mice exposed to RFR at power densities of 0.000168 - 0.001053 mW/cm2.
(16) Mann et al. (1998)- a transient increase in blood cortisol was observed in human subjects exposed to cellular phone RFR at 0.02 mW/cm2. Cortisol is a hormone involved in stress reaction.
(17) Michelozzi et al. (1998)- leukemia mortality within 3.5 km (5,863 inhabitants) near a high power radio-transmitter in a peripheral area of Rome was higher than expected.
(18) Michelozzi et al. (2002)- childhood leukemia higher at a distance up to 6 km from a radio station.
(19) Navakatikian and Tomashevskaya (1994)- RFR at low intensities (0.01 - 0.1 mW/cm2; 0.0027- 0.027 W/kg) induced behavioral and endocrine changes in rats. Decreases in blood concentrations of testosterone and insulin were reported.
(20) Novoselova et al. (1999)-low intensity RFR (0.001 mW/cm2) affects functions of the immune system.
(21) Persson et al. (1997) reported an increase in the permeability of the blood-brain barrier in mice exposed to RFR at 0.0004 - 0.008 W/kg. The blood-brain barrier envelops the brain and protects it from toxic substances.
(22) Phillips et al. (1998) reported DNA damage in cells exposed to RFR at SAR of 0.0024 - 0.024 W/kg.
(23) Santini et al. (2002)- increase in complaint frequencies for tiredness, headache, sleep disturbance, discomfort, irritability, depression, loss of memory, dizziness, libido decrease, in people who lived within 300 m of mobile phone base stations.
(24) Schwartz et al. (1990)- calcium movement in the heart affected by RFR at SAR of 0.00015 W/kg. Calcium is important in muscle contraction. Changes in calcium can affect heart functions.
(25) Somosy et al. (1991)- RFR at 0.024 W/kg caused molecular and structural changes in cells of mouse embryos.
(26) Stagg et al. (1997)- glioma cells exposed to cellular phone RFR at 0.0059 W/kg showed significant increases in thymidine incorporation, which may be an indication f an increase in cell division.
(27) Stark et al. (1997)- a two- to seven-fold increase of salivary melatonin concentration was observed in dairy cattle exposed to RFR from a radio transmitter antenna.
(28) Tattersall et al. (2001)- low-intensity RFR (0.0016 - 0.0044 W/kg) can modulate the function of a part of the brain called the hippocampus, in the absence of gross thermal effects. The changes in excitability may be consistent with reported behavioral effects of RFR, since the hippocampus is involved in learning and memory.
(29) Vangelova et al. (2002)- operators of satellite station exposed to low dose (0.1127 J/kg) of RFR over a 24-hr shift showed an increased excretion of stress hormones.
(30) Velizarov et al. (1999) showed a decrease in cell proliferation (division) after exposure to RFR of 0. 000021 - 0.0021 W/kg. (31) Veyret et al. (1991)- low intensity RFR at SAR of 0.015 W/kg affects functions of the immune system.
(32) Wolke et al. (1996)- RFR at 0.001W/kg affects calcium concentration in heart muscle cells of guinea pigs.

Some of these effects occurred at surprisingly low intensities or SARs. It is apparent that low-intensity RFR is not biologically inert. When using a cell phone, because of the closeness of the antenna, a large amount of energy can be deposited in the head of a user. Relatively high SARs have been reported in various studies: Dimbylow and Mann (1994)- 2.3 and 4.8 W/kg/gm tissue per W output at 900 MHz and 1.8 GHz; Anderson and Joyner (1995)- 0.12-0.83 W/kg; Gandhi et al. (1999)- 0.13-5.41 W/kg/gm tissue at 0.6 W output (835 and 1900 MHz); and Van de Kamer and Lagendijk (2002)- 1.72-2.55 W/kg /gm tissue at 0.25 W output (915 MHz).

The majority of the biological studies on RFR have been conducted with short-term exposures, i.e. a few minutes to several hours. Little is known about the effects of long-term exposure. What are the effects of long-term exposure? Does long-term exposure produce different effects from short-term exposure? Do effects accumulate over time?

Various biological outcomes have been reported after long-term/repeated exposure to RFR: (1) Effects were observed after prolonged, repeated exposure but not after short-term exposure [e.g., Baranski, 1972; Takashima et al., 1979].
(2) Effects that were observed after short-term exposure, disappeared after prolonged, repeated exposure (habituation) [e.g., Johnson et al., 1983; Lai et al., 1987, 1992].
(3) Different effects were observed after different durations of exposure [e.g., Di Carlo et al., 2002; Dumanski and Shandala, 1974; Lai et al., 1989].
(4) There is also indication that an animal becomes more sensitive to the radiation after long-term exposure [e.g., see de Lorge and Ezell, 1980; de Lorge 1984, D’Andrea et al. 1986a,b; DeWitt et al., 1987]. The conclusion from a series of experiments on ‘disruption of behavior’ in animals after one-time exposure to RFR is that ‘disruption of behavior occurred when an animal was exposed at a SAR of approximately 4 W/kg, and disruption occurred after 30-60 minutes of exposure’. However after long-term exposure (7 hr/day, 7 days/week for 90 days14 weeks), the threshold for behavioral and physiological effects of RFR was found to occur between 0.14 W/kg and 0.7 W/kg. Thus, RFR can produce an effect at much lower intensities after an animal is chronically exposed. This can have very significant implications for people exposed to RFR in the environment. The conclusion from this body of work is that effects of long-term exposure can be quite different from those of short-term exposure.

There is also some evidence that effects of RFR accumulate over time. Here are some examples: Phillips et al. (1998) reported DNA damage in cells after 24 hours of exposure to low intensity RFR. DNA damage can lead to gene mutation, which accumulates over time. Magras and Xenos (1999) reported that mice exposed to low-intensity RFR became less reproductive. After five generations of exposure, the mice were not able to produce offspring. This shows that the effect of RFR can pass from one generation to another. Persson et al. (1997) reported an increase in permeability of the blood-brain barrier in mice when the energy deposited in the body exceeded 1.5 J/kg (joule per kilogram) -- a measurement of the total amount of energy deposited. This suggests that a short-term/high intensity exposure can produce the same effect as a long-term/low intensity exposure. This is another indication that RFR effects can accumulate over time.

In many RFR exposure guidelines, a limit of 0.4 W/kg is used based on the experimental results that ‘disruption of behavior’ in animals occurs at 4 W/kg. However, there are many studies that show biological effects at SARs less than 4 W/kg after short-term exposure to RFR. For example, behavioral effects have been observed at SARs less than 4 W/kg: D’Andrea et al (1986a,b)- 0.14 to 0.7 W/kg; DeWitt et al. (1987)- 0.14 W/kg; Gage (1979)- 3 W/kg; King et al. (1971)- 2.4 W/kg; Lai et al. (1989)- 0.6 W/kg; Mitchell et al. (1977)- 2.3 W/kg; Navakatikian and Tomashevskaya (1994)- 0.027 W/kg; Schrot et al. (1980)- 0.7 W/kg; Thomas et al. (1975)- 1.5 to 2.7 W/kg; Wang and Lai (2000)- 1.2 W/kg . There are also many reports of other biological functions affected by RFR at a SAR less than 4 W/kg. Therefore, the rationale of 4 W/kg should be reconsidered.

For decades, there have been questions about whether an effect of RFR is thermal (i.e., a significant change in temperature) or non-thermal (i.e., no significant change in temperature). However, we actually don’t need to know whether RFR effects are thermal or non-thermal to set exposure guidelines for RFR exposure. Most of the studies on biological effects of RFR carried out since the 1980’s were under ‘non-thermal’ conditions. In studies using isolated cells, the ambient temperature during exposure was generally well controlled. In most animal studies, the RFR intensity used usually did not cause a significant increase in body temperature of the animals exposed. There are several arguments for the existence of non-thermal effects: (1) There are reports that RFRs of the same frequency and intensity but with different modulations and waveforms produce different effects [Arber and Lin, 1985; Baranski, 1972; Frey et al., 1975; Oscar and Hawkins, 1977; Sanders et al., 1985]. (2) RFR triggers effects different from an increase in temperature [de Pomerai et al., 2002; D'Inzeo et al., 1988; Seaman and Wachtel, 1978; Wachtel et al., 1975]. (3) Effects are observed with RFR of very low intensities, when temperature increase is unlikely [e.g., de Pomerai et al., 2000].

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