Bioelectromagnetics 13:601-604 (1992)
Electromagnetic Fields and Health: Some Thoughts About the Past and Future Arthur W. Guy Center for Bioengineering, University of Washington, Seattle
I was overwhelmed with emotion in the recall of pleasant memories of events and of colleagues with whom I have roamed the fields of bioelectromagnetics. These memories were triggered by the symposium reported in this special issue. I owe a great debt of gratitude and thanks to C.-K. Chou and to the many colleagues and friends who contributed their talents, time, and resources to make my retirement from an academic career one of the most memorable events of my life. The symposium brought together people who not only are close personal friends but also are scientists who have made major contributions in clarifying and quantifying biological effects of electromagnetic (EM) fields, an area in which I have spent the major part of my professional life. In responding to C.-K. Chou’s request to comment on the future of bioelectromagnetics, I must take the opportunity to note the influence that the 15 scientists who contributed to the symposium or this publication have had-and will have-on the development of bioelectromagnetics as a discipline. My colleagues and I are very fortunate to have followed Professor Herman Schwan into the multidisciplinary arena of bioelectromagnetics. Schwan’s contributions in quantifying electrical properties of biological tissues, and the influence of these properties on EM propagation through, scattering from, and interaction with, tissues, are legendary, and they have come to be the foundation of our work in bioelectromagnetics. Don Justesen was singular in the late 1960s in pleading the case for microwave dosimetry in conjunction with dose-controlled experimentation on intact animals. In association with his doctoral student, Nancy King, he championed the use of the whole-body-averaged integral and time rate of energy deposition in behavioral studies of small animals, the data of which, after extensive independent verification, became the hazard-marker of the ANSI 1982 RF standards and most other RF standards here and abroad. The dosimetry quantities, now termed specific absorption ( S A ) and specific absorption rate (SAR), have become very important measures for establishing thresholds of biological effects in experimental animals, and they are prime constructs in the development of safe exposure guidelines. A major player in the provision of resources for and influence on the advancement of RF dosimetry and its role in quantifying the biological response to EM fields has been the US Air Force School of Aerospace Medicine under the direction and leadership of John Mitchell and his staff of able scientists, which include Dave Erwin, 0 1992 Wiley-Liss, Inc.
602
Guy
James Merritt, and Jerome Krupp. In addition to their own work in evaluating effects of EM fields on pacemakers and laboratory animals, they have provided access to high-tech exposure facilities and generous support to the highly productive laboratories of Carl Durney, Om Gandhi, and their colleagues at the University of Utah. This work has led to highly advanced theoretical and numerical quantitation of RF energy absorption by laboratory animals and human subjects exposed to EM fields. A continuing line of spheroidal, ellipsoidal, cylindrical, and man-shaped models has been developed for calculating whole-body-averaged and distributive SARs in a wide range of laboratory animals and human beings. The results of these labors have been published in The Rudiofiequclzcy Dosimetry Handbooks, which have been very useful to investigators of higher frequency RF fields and a host of standardssetting groups. In a parallel effort, the Air Force supported the work in our laboratory at the University of Washington, which enabled C.-K. Chou, James Lin, and me, along with numerous students, to advance the experimental use of thermography and modeling by which to quantify the SAR as a distributive measure. We were enabled also to design and create new exposure systems and techniques by which to measure heating patterns in human tissues; these efforts have facilitated diathermy and hyperthermic therapy. At the same time, through the support of the National Science Foundation and Tom Rozzell’s group at the Office of Naval Research, C.-K. Chou and James Lin and I became interested in the microwave-hearing effect, the thresholds and electrical properties of which we were able to characterize in laboratory animals. Dick Lovely and his student, Robert Johnson, found that rats trained to respond to pulses of sound readily transferred the response to pulsed microwaves. Thermoelastic expansion as the mechanism for the microwave hearing phenomenon was later demonstrated by Kenneth Foster in an elegant experiment on aqueous models. Ken Foster’s work was confirmed and extended by C.-K. Chou’s and Robert Galambos’s recordings of cochlear microphonics from different species exposed to microwave pulses. These experiments and others were convincing demonstrations of a role played by intracranial resonance in the hearing effect. James Lin later wrote a text on the hearing effect, and C.-K. Chou wrote a review and tutorial article on the subject for the Journal ojAcoustic Society uf America. C.-K. Chou, Larry Kunz, and Robert Johnson played major roles in experimental design, animal preparation, and data collection and analysis in the life-time rat-exposure experiment, which was sponsored by the US Air Force, monitored by Jerome Krupp, and performed in my laboratory. The statistical analyses of data in this complicated, important project were performed by John Crowley with the help of his student, Desmond Thomas. Eleanor Adair, whose work has also been sponsored by the Air Force, has been a pioneer in interrelating data on temperature, humidity, and SAR to behavioral and thermoregulatory thresholds of primates exposed to microwaves. Without her rigorously drawn data on the primate’s response to microwaves, we would be far less comfortable in forecasting the response to microwaves of the highest primate, the human being. Her work is complemented and confirmed by that of John de Lorge and colleagues at the Navy’s Aeromedical Research Laboratories in Pensacola, Florida. John did not attend the symposium, but he remains vivid in my recall of the movers and shakers of bioelectromagnetics.
Festschrift
603
With the help of funding from the National Institute of Environmental Health Sciences, Henry Lai is performing important work on laboratory animals in defining dose-response relations and establishing thresholds for combined effects of mindaltering drugs and pulsed microwaves. Ron Peterson has made significant contributions in developing instrumentation and measurement techniques for quantifying radiation from microwave dishes, cellular telephone systems, and video display terminals. Last but not least is the importance of resolving some of the questions regarding human health and power lines raised by a number of epidemiological studies. Of great importance, as is the case of interpreting biological effects of microwaves, is the role of dosimetry in answering the questions raised by concerns for extremely low frequency (ELF) fields. Without question, Bill Kaune has been, and remains, the pioneer whom I consider to be the most productive and influential individual in the quest to define the electromagnetic variables that control the biological response to ELF fields. Unfortunately, Bill was unable to be present at the symposium or provide a paper for this special issue, but the substance and importance of his work mandates mention here. Having acknowledged the past work of 15 colleagues who have contributed to this special issue and the symposium, I can further state that their work provides a firm foundation for the future course of bioelectromagnetics in terms of better quantitation of the harmful effects as well as useful medical applications of EM fields. At present, most consensus-derived exposure guidelines for exposing human beings to fields at the higher R F frequencies are based on a whole-body-averaged SAR limit of 0.4 Wlkg and a peak-SAR limit of 8 Wlkg. There are a few scientists who consider these levels too high because of reports of biological “effects” at comparable or lower SARs. However, the reports of low-level effects, as well as others that might appear in the literature, will have little influence on consensusderived guidelines unless they satisfy four important standard setting criteria: 1) experimental evidence of a weak-field effect must be confirmed in independent investigations in different laboratories to establish reliability and inspire confidence in the results; 2) the observed effect must be demonstrated in different species of animals-preferably in primates-and not be a peculiar characteristic of a particular organism that shares few attributes with human beings; 3) effects must be demonstrably hazardous; and 4)the field conditions required to demonstrate a hazardous effect must be specifiable and reproducible. Once the first two standard-setting criteria are satisfied, which ensures that an observed effect is real and applicable to the human being, research needs to be done to determine whether the observed effect poses a hazard. Ideally, the research would reveal the mechanism of interaction, as was done in the case of the microwave-hearing phenomenon. The standard-setting criteria I have listed would also apply when making a judgment as to the efficacy and safety of medical applications of EM fields, such as current-induced bone and tissue healing, magnetic resonance imaging (MRI), and hyperthermia. Finally, it is obvious that endangerment thresholds or pertinent doseresponse functions in terms of electromagnetic quantities must be established before a truly protective standard is feasible. The application of quantitative dosimetry in all future experimental work, as developed by the authors of this special issue, will be very important in satisfying the above criteria. With the widespread distribution and use of new numerical dosimetry software, coupled with the eventual
604
Guy
proliferation of highly powered desktop computers and work stations with speeds of 100 to 400 millions of instructions per second (MIPS), any bioelectromagnetics laboratory will be able rapidly and accurately to quantify, in three dimensions and time, the required dosimetry for various experiments regardless of the geometry and mass of the organism under exposure. Of great importance for the future of bioelectromagnetics is better communication with the media and the public as to the origin and explanation of biological effects, exposure guidelines, and how the guidelines apply to the electromagnetic devices that are so much a part of our everyday life. The need for public education about such matters is exemplified by the current police-radar controversy. It is ironic that the broadcast industry continuously exposes the North American population to tens of megawatts of electromagnetic radiation at frequencies in the bands of maximal absorption by the human body-and with modulated signals, which often are reported to cause biological effects. It is ironic because TV programs like CBS’s 60 Minutes will fill the ether with its megawatt radiations in questioning the safety of an unmodulated, 50-milliwatt, continuous-wave, police radar that operates at a frequency at which the energy is absorbed mostly in the skin. The public is indeed misinformed when police radars can be banned, as happened in the state of Connecticut, to remove unfounded perceptions of danger to the highway patrolman, while increasing the real risk of injury and death to the motorist and public. Although newly retired from full-time academic life, I look forward to continued contact with the field of bioelectromagnetics and with my many colleagues. I shall enjoy reading about and learning of exciting new developments in the field in perusing Bioelectromagnetics and the BEMS Newsletter, and I shall enjoy attending the annual meetings of the Bioelectromagnetics Society. I hope to continue some involvement with research by assisting my colleague and good friend Dr. Henry Lai at the University of Washington and by serving on various committees and working groups that deal with research priorities, public health, and safety standards as these relate to biological effects of EM fields. Finally, in closing, I would like to make a plea to all bioelectromagnetics researchers to consider that the source of most of their research funding is taxation of the public, which is suffering a great deal of confusion as to the safety of devices and systems that utilize EM energy. In addition to the responsibility to report their work in peer-reviewed scientific journals, I believe researchers have an even greater responsibility to inform and educate the public in lay terms as to the scientific meaning and health implications of their work.
(Photo by C.-K. Chou at Jameson Lake, WA in October 1978)
Happy retirement, Bill!
605
Electromagnetic Fields and Health: Some Thoughts About the Past and Future Arthur W. Guy Center for Bioengineering, University of Washington, Seattle
I was overwhelmed with emotion in the recall of pleasant memories of events and of colleagues with whom I have roamed the fields of bioelectromagnetics. These memories were triggered by the symposium reported in this special issue. I owe a great debt of gratitude and thanks to C.-K. Chou and to the many colleagues and friends who contributed their talents, time, and resources to make my retirement from an academic career one of the most memorable events of my life. The symposium brought together people who not only are close personal friends but also are scientists who have made major contributions in clarifying and quantifying biological effects of electromagnetic (EM) fields, an area in which I have spent the major part of my professional life. In responding to C.-K. Chou’s request to comment on the future of bioelectromagnetics, I must take the opportunity to note the influence that the 15 scientists who contributed to the symposium or this publication have had-and will have-on the development of bioelectromagnetics as a discipline. My colleagues and I are very fortunate to have followed Professor Herman Schwan into the multidisciplinary arena of bioelectromagnetics. Schwan’s contributions in quantifying electrical properties of biological tissues, and the influence of these properties on EM propagation through, scattering from, and interaction with, tissues, are legendary, and they have come to be the foundation of our work in bioelectromagnetics. Don Justesen was singular in the late 1960s in pleading the case for microwave dosimetry in conjunction with dose-controlled experimentation on intact animals. In association with his doctoral student, Nancy King, he championed the use of the whole-body-averaged integral and time rate of energy deposition in behavioral studies of small animals, the data of which, after extensive independent verification, became the hazard-marker of the ANSI 1982 RF standards and most other RF standards here and abroad. The dosimetry quantities, now termed specific absorption ( S A ) and specific absorption rate (SAR), have become very important measures for establishing thresholds of biological effects in experimental animals, and they are prime constructs in the development of safe exposure guidelines. A major player in the provision of resources for and influence on the advancement of RF dosimetry and its role in quantifying the biological response to EM fields has been the US Air Force School of Aerospace Medicine under the direction and leadership of John Mitchell and his staff of able scientists, which include Dave Erwin, 0 1992 Wiley-Liss, Inc.
602
Guy
James Merritt, and Jerome Krupp. In addition to their own work in evaluating effects of EM fields on pacemakers and laboratory animals, they have provided access to high-tech exposure facilities and generous support to the highly productive laboratories of Carl Durney, Om Gandhi, and their colleagues at the University of Utah. This work has led to highly advanced theoretical and numerical quantitation of RF energy absorption by laboratory animals and human subjects exposed to EM fields. A continuing line of spheroidal, ellipsoidal, cylindrical, and man-shaped models has been developed for calculating whole-body-averaged and distributive SARs in a wide range of laboratory animals and human beings. The results of these labors have been published in The Rudiofiequclzcy Dosimetry Handbooks, which have been very useful to investigators of higher frequency RF fields and a host of standardssetting groups. In a parallel effort, the Air Force supported the work in our laboratory at the University of Washington, which enabled C.-K. Chou, James Lin, and me, along with numerous students, to advance the experimental use of thermography and modeling by which to quantify the SAR as a distributive measure. We were enabled also to design and create new exposure systems and techniques by which to measure heating patterns in human tissues; these efforts have facilitated diathermy and hyperthermic therapy. At the same time, through the support of the National Science Foundation and Tom Rozzell’s group at the Office of Naval Research, C.-K. Chou and James Lin and I became interested in the microwave-hearing effect, the thresholds and electrical properties of which we were able to characterize in laboratory animals. Dick Lovely and his student, Robert Johnson, found that rats trained to respond to pulses of sound readily transferred the response to pulsed microwaves. Thermoelastic expansion as the mechanism for the microwave hearing phenomenon was later demonstrated by Kenneth Foster in an elegant experiment on aqueous models. Ken Foster’s work was confirmed and extended by C.-K. Chou’s and Robert Galambos’s recordings of cochlear microphonics from different species exposed to microwave pulses. These experiments and others were convincing demonstrations of a role played by intracranial resonance in the hearing effect. James Lin later wrote a text on the hearing effect, and C.-K. Chou wrote a review and tutorial article on the subject for the Journal ojAcoustic Society uf America. C.-K. Chou, Larry Kunz, and Robert Johnson played major roles in experimental design, animal preparation, and data collection and analysis in the life-time rat-exposure experiment, which was sponsored by the US Air Force, monitored by Jerome Krupp, and performed in my laboratory. The statistical analyses of data in this complicated, important project were performed by John Crowley with the help of his student, Desmond Thomas. Eleanor Adair, whose work has also been sponsored by the Air Force, has been a pioneer in interrelating data on temperature, humidity, and SAR to behavioral and thermoregulatory thresholds of primates exposed to microwaves. Without her rigorously drawn data on the primate’s response to microwaves, we would be far less comfortable in forecasting the response to microwaves of the highest primate, the human being. Her work is complemented and confirmed by that of John de Lorge and colleagues at the Navy’s Aeromedical Research Laboratories in Pensacola, Florida. John did not attend the symposium, but he remains vivid in my recall of the movers and shakers of bioelectromagnetics.
Festschrift
603
With the help of funding from the National Institute of Environmental Health Sciences, Henry Lai is performing important work on laboratory animals in defining dose-response relations and establishing thresholds for combined effects of mindaltering drugs and pulsed microwaves. Ron Peterson has made significant contributions in developing instrumentation and measurement techniques for quantifying radiation from microwave dishes, cellular telephone systems, and video display terminals. Last but not least is the importance of resolving some of the questions regarding human health and power lines raised by a number of epidemiological studies. Of great importance, as is the case of interpreting biological effects of microwaves, is the role of dosimetry in answering the questions raised by concerns for extremely low frequency (ELF) fields. Without question, Bill Kaune has been, and remains, the pioneer whom I consider to be the most productive and influential individual in the quest to define the electromagnetic variables that control the biological response to ELF fields. Unfortunately, Bill was unable to be present at the symposium or provide a paper for this special issue, but the substance and importance of his work mandates mention here. Having acknowledged the past work of 15 colleagues who have contributed to this special issue and the symposium, I can further state that their work provides a firm foundation for the future course of bioelectromagnetics in terms of better quantitation of the harmful effects as well as useful medical applications of EM fields. At present, most consensus-derived exposure guidelines for exposing human beings to fields at the higher R F frequencies are based on a whole-body-averaged SAR limit of 0.4 Wlkg and a peak-SAR limit of 8 Wlkg. There are a few scientists who consider these levels too high because of reports of biological “effects” at comparable or lower SARs. However, the reports of low-level effects, as well as others that might appear in the literature, will have little influence on consensusderived guidelines unless they satisfy four important standard setting criteria: 1) experimental evidence of a weak-field effect must be confirmed in independent investigations in different laboratories to establish reliability and inspire confidence in the results; 2) the observed effect must be demonstrated in different species of animals-preferably in primates-and not be a peculiar characteristic of a particular organism that shares few attributes with human beings; 3) effects must be demonstrably hazardous; and 4)the field conditions required to demonstrate a hazardous effect must be specifiable and reproducible. Once the first two standard-setting criteria are satisfied, which ensures that an observed effect is real and applicable to the human being, research needs to be done to determine whether the observed effect poses a hazard. Ideally, the research would reveal the mechanism of interaction, as was done in the case of the microwave-hearing phenomenon. The standard-setting criteria I have listed would also apply when making a judgment as to the efficacy and safety of medical applications of EM fields, such as current-induced bone and tissue healing, magnetic resonance imaging (MRI), and hyperthermia. Finally, it is obvious that endangerment thresholds or pertinent doseresponse functions in terms of electromagnetic quantities must be established before a truly protective standard is feasible. The application of quantitative dosimetry in all future experimental work, as developed by the authors of this special issue, will be very important in satisfying the above criteria. With the widespread distribution and use of new numerical dosimetry software, coupled with the eventual
604
Guy
proliferation of highly powered desktop computers and work stations with speeds of 100 to 400 millions of instructions per second (MIPS), any bioelectromagnetics laboratory will be able rapidly and accurately to quantify, in three dimensions and time, the required dosimetry for various experiments regardless of the geometry and mass of the organism under exposure. Of great importance for the future of bioelectromagnetics is better communication with the media and the public as to the origin and explanation of biological effects, exposure guidelines, and how the guidelines apply to the electromagnetic devices that are so much a part of our everyday life. The need for public education about such matters is exemplified by the current police-radar controversy. It is ironic that the broadcast industry continuously exposes the North American population to tens of megawatts of electromagnetic radiation at frequencies in the bands of maximal absorption by the human body-and with modulated signals, which often are reported to cause biological effects. It is ironic because TV programs like CBS’s 60 Minutes will fill the ether with its megawatt radiations in questioning the safety of an unmodulated, 50-milliwatt, continuous-wave, police radar that operates at a frequency at which the energy is absorbed mostly in the skin. The public is indeed misinformed when police radars can be banned, as happened in the state of Connecticut, to remove unfounded perceptions of danger to the highway patrolman, while increasing the real risk of injury and death to the motorist and public. Although newly retired from full-time academic life, I look forward to continued contact with the field of bioelectromagnetics and with my many colleagues. I shall enjoy reading about and learning of exciting new developments in the field in perusing Bioelectromagnetics and the BEMS Newsletter, and I shall enjoy attending the annual meetings of the Bioelectromagnetics Society. I hope to continue some involvement with research by assisting my colleague and good friend Dr. Henry Lai at the University of Washington and by serving on various committees and working groups that deal with research priorities, public health, and safety standards as these relate to biological effects of EM fields. Finally, in closing, I would like to make a plea to all bioelectromagnetics researchers to consider that the source of most of their research funding is taxation of the public, which is suffering a great deal of confusion as to the safety of devices and systems that utilize EM energy. In addition to the responsibility to report their work in peer-reviewed scientific journals, I believe researchers have an even greater responsibility to inform and educate the public in lay terms as to the scientific meaning and health implications of their work.
(Photo by C.-K. Chou at Jameson Lake, WA in October 1978)
Happy retirement, Bill!
605
