ABSTRACT

CONTENTS 3.1 Introduction ......................................................................................................................... 54

3.1.1 Thermal versus Athermal or Nonthermal Effects ............................................ 55 3.1.2 Vagaries and Pitfalls in the Literature ................................................................ 56 3.1.3 Physical and Physiologic Scaling......................................................................... 56 3.1.4 Specific Absorption Rate ....................................................................................... 59

3.2 Response to Local Radio Frequency Exposure.............................................................. 60 3.3 Biochemical Changes ......................................................................................................... 60 3.4 Cellular and Molecular Biology ....................................................................................... 62

3.4.1 Chromosome and Genetic Effects........................................................................ 63 3.4.2 Kinetic or Functional Changes and Membrane Effects.................................... 66

3.5 Reproduction, Growth, and Development ..................................................................... 68 3.5.1 Reproduction........................................................................................................... 68 3.5.2 Embryonic Development and Teratology .......................................................... 70 3.5.3 Postnatal Development and Behavior................................................................. 77

3.6 Effects on the Nervous System......................................................................................... 77 3.6.1 Electroencephalographic Changes....................................................................... 79 3.6.2 Calcium Efflux ........................................................................................................ 81 3.6.3 Histopathology........................................................................................................ 81 3.6.4 Effects on the Blood-Brain Barrier ...................................................................... 83 3.6.5 Combined Effect of Radio Frequency and Drugs, and Radio

Frequency Effects on Neurotransmitters............................................................ 87 3.6.6 Neurophysiologic Effects In Vitro........................................................................ 89

3.7 Behavioral Effects ............................................................................................................... 90 3.7.1 Experimental Behavioral Studies......................................................................... 90 3.7.2 Behavioral Thermoregulation............................................................................... 94

3.8 Neuroendocrine Effects ..................................................................................................... 96 3.8.1 Mechanisms of Interaction.................................................................................... 96 3.8.2 Hypothalamic-Hypophysial-Adrenal Response .............................................. 97 3.8.3 Hypothalamic-Hypophysial-Thyroid Response .............................................. 98 3.8.4 Melatonin Response ............................................................................................... 99

3.9 Cardiovascular Effects ..................................................................................................... 99 3.10 Effects on Hematopoiesis and Hematology ............................................................... 101 3.11 Effects on the Immune Response................................................................................. 103

3.11.1 Lymphocyte Kinetics........................................................................................ 103 3.11.2 Adaptation ......................................................................................................... 106 3.11.3 Influence of Hyperthermia.............................................................................. 106

3.12 Carcinogenesis................................................................................................................. 107 3.12.1 Long-Term Animal Studies............................................................................. 107 3.12.2 Radiation or Chemically Initiated and Transgenic

Animal Bioassays .............................................................................................. 108 3.12.3 Tumor Cell Injection Bioassays ...................................................................... 109 3.12.4 Summary of Animal Cancer Bioassays......................................................... 109

3.13 Other Specialized Organ Response ............................................................................. 109 3.13.1 Auditory Response........................................................................................... 109 3.13.2 Ocular Effects .................................................................................................... 110

3.13.2.1 Threshold for Opacity in Rabbits.................................................. 110 3.13.2.2 Biochemical Changes ...................................................................... 111 3.13.2.3 Thermal Aspect of Microwave Cataractogenesis ....................... 111 3.13.2.4 Pulse Wave Exposures.................................................................... 111 3.13.2.5 Cumulative Effect ............................................................................ 111 3.13.2.6 Extrapolation to the Human .......................................................... 112

3.13.3 Hypersensitivity................................................................................................ 113 3.14 Critique............................................................................................................................. 113 Acknowledgment....................................................................................................................... 115 References ................................................................................................................................... 115

Over the past several decades, research on electromagnetic fields (EMF) has been motivated primarily by public health considerations. Through the 1980s and early 1990s, investigations of extremely low-frequency (ELF) were preeminent in EMF research due to increased societal concerns in the area of power frequency. Thiswork focused on biological effects of power transmission lines and appliances. Since the mid-1990s, however, as human-made sources of radio frequency (RF) energy continued to increase in the environment, so also did environmental and health concerns. Due to elevated levels of RF exposure, specifically the exponential increase in exposure from cellular telephony, the output from RF effects research has increased significantly since the publication of the last edition of the handbook, as judged from a survey of leading research journals from 1994 to 2004. Other factors have also influenced the enthusiasm with which new investigators have

ventured into EMF research and have affected the motivation of research administrators who influence public policy on resource allocation. Concerns over nonreproducibility of results and nonrobustness of effects have produced a voluble exchange of views on direction and magnitude of support for EMF research (Pickard and Foster 1987). Such problems are brought into focus by the fact that the database of this research typically enters directly into the public health policy forum and is used to establish permissible exposure limits, directly affecting diverse economic interests (IEEE 1991). EMF research is therefore subjected to a second, critical review, following scholarly peer review but in a more pragmatic context. The veracity of the work is again analyzed and, in addition, its

relevance for formulating safe limits for human exposure is scrutinized. This exercise requires extrapolation from conditions of experiments, often with animals, to human exposure. Inevitably the process requires the imposition of interpretations and judgments as to whether an effect might or might not constitute a hazard to humans and the database is seldom clear on that point. Utilization of the database in standards setting has been described by Petersen (1991). The role of culture and philosophy in the divergence of Eastern European and Western safety standards has been the subject of commentary by Sliney et al. (1985). The fundamental interaction of RF radiation (3 kHz to 300 GHz (IEEE 1991)) with

biological systems is set forth in detail in other chapters of this book. At sufficiently high RF intensities bulk thermal energy is imparted to the system, causing an increase in random kinetic energy and temperature. The thermal gradients differ from those of ambient heating, a fact that is marshaled occasionally to explain differences in effects between RF and ambient heating. Above certain intensities RF energy can quickly produce morbidity, and, after thermoregulatory mechanisms are overwhelmed, mortality. In recent years, work has focused on possible effects at nonthermal levels or under conditions in which physiologic temperature can be maintained in the presence of normally thermalizing specific absorption rates (SAR). Studies of human perception indicate that the greatest cutaneous sensitivity to micro-

wave (MW) heating is at frequencies with wavelengths comparable to or smaller than the thickness of skin, the millimeter wave range (EPA 1984). In this range, most of the energy is absorbed in the superficial dermis containing thermal sensors. At lower frequencies, 1 to 10 GHz, with wavelengths equal to or longer than the human body, much of the energy is absorbed below the superficial dermis. In this range, the threshold temperature for cellular injury about 428C is below the threshold for pain (about 458C). Consequently cutaneous perception of RF energy may not be a reliable response, which protects against potentially harmful levels of RF radiation at the lower microwave frequencies (Hardy, 1978).