In this paper, William H. Bailey, Ph.D. provides an overview describing how radiofrequency communication works, the role of small cells in transmitting radiofrequency energy, how radiofrequency exposure standards have been developed, and a summary of the state of health research on radiofrequency energy.
Key Excerpts:
On FCC standard: “The earliest studies of RF identified the effects of exposure arising from the heating of water molecules as the result of friction by the movement of atoms or molecules. It was then determined that RF heating did not change the structure of molecules by ionization. Research over many decades confirmed these observations and informed the basis for health and safety standards. The FCC standard, like many other national and international RF standards, was set to ensure that exposure does not reach a level that would raise whole body temperature. An increase in body temperature by a small amount—much like what we experience when we exercise, or go through any number of daily occurrences—is actually not an adverse outcome, and one to which the body is used to routinely adapting, but the FCC exposure limit is set to avoid any such increase, and is set below the level at which minor behavioral changes in animals occur with body heating (IEEE/ANSI, 1992; FCC/OET, 1999; IEEE, 2019).
This means that for a member of the general public, the whole-body exposure limit to RF at frequencies above 2 GHz is 50 times lower than this threshold. The FCC standard is designed to protect everyone, including populations such as children and the elderly, from the effects known to occur with sufficiently high exposure to RF energy (i.e., raising the temperature of exposed body tissues).”
On common characteristics of RF energy below 300 GHz: “As new 5G communication systems are proposed and deployed, some have raised questions as to whether enough health and safety research has been performed on the new frequency bands above those used by existing 2G, 3G, and 4G systems. Although additional research is always useful in making evaluations, the commonality of RF exposure characteristics up to 300 GHz has enabled health agencies and standard-setting committees to assess the potential effects across this spectrum based on all the evidence, not just at a single frequency.
The simple reason for considering research on all RF frequencies in assessments is that although RF signals are distinguished by different frequencies, it does not mean their fundamental properties are vastly different. In this regard, it is useful to compare frequencies of RF (e.g., between 100 kHz and 300 GHz) to the tones created by striking different keys on a piano (Figure 4). At one end of the keyboard, the keys create sound waves with lower frequencies (left side) than at the upper end of the keyboard (right side). But a melody played on the keys at the lower end is no different than a melody played on keys at the upper end and the sound intensity is similar. Neither does a higher frequency 5G RF signal have a different mode of action than at a lower frequency RF communication signal; both involve tissue heating at sufficient field strengths. In addition, a higher frequency RF signal does not necessarily have a greater intensity than a lower frequency RF signal, especially since extensive signal processing and RF signal reception techniques allow receivers to recover signals that are thousands of times below background exposure. This is analogous to a human’s ability to recognize a very quiet voice in a loud crowded room. To date, the only confirmed biological difference between exposures to RF at frequencies less than 6 GHz and RF frequencies above 6 GHz is that at the higher frequencies the body’s electrical properties better limit energy deposition to a shallow depth, largely confined to the skin. Thus, at frequencies above 6 GHz the hazard to be avoided is painful heating of the skin.”
About the author:
William H. Bailey, Ph.D., is a health scientist and researcher in the Center for Occupational and Environmental Health Risk Assessment at Exponent, Inc., an international scientific and engineering firm. His work over the past 35+ years relates to the exposures and potential biological, environmental, and health effects associated with electromagnetic fields and RF signals produced by a wide variety of electrical facilities and devices, including wireless communication systems, electric utility facilities, electrified railroad lines, industrial equipment, appliances, and medical devices. Dr. Bailey also is an Associate Editor of the journal Health Physics, with primary responsibility for the peer review of manuscripts describing the results of research on electromagnetic fields including both RF and other frequencies, a role he also served in as a grant reviewer for the U.S. National Institutes of Health. He participated in setting standards for RF and extremely low-frequency fields for the IEEE’s International Committee on Electromagnetic Safety, and he also served as an elected member of the Committee on Man and Radiation of the IEEE Engineering in Medicine and Biology Society from 1998–2001. In addition, he has served as an advisor on health risk assessments and public policy to various international scientific and health agencies, including the WHO, on topics relating to electromagnetic fields. Dr. Bailey has published or presented more than 90 scientific papers on this and related subjects.