Subcellular Responses to Narrowband
and Wideband Radio Frequency Radiation

Radiofrequency (RF) radiation is an important part of electromagnetic human exposure. This is due to fact that in this frequency range the electromagnetic skin depth is such that the entire body is affected, not just the surface layers. Secondly, it is the frequency range where the outer membranes of mammalian cells are no longer barriers to electric fields, allowing access of the RF to subcellular structures. In spite of a host of publication, there are few coherent approaches exploring RF effects on cells. None of them considers both the effect of narrow band, quasi-continuous radiation (duration of exposure long compared to cell time constants) and wideband radiation, radiation with a pulse duration comparable to or less than characteristic cell time constants (i.e., charging time of outer and subcellular membranes and dipolar relaxation time of proteins). Although the impulse radiation is much higher in power, the energy delivered to cells by either of the two radiative modes can be comparable. However, whereas narrow band radiation is only expected to affect biomolecular functions, such as expressions of proteins, wideband radiation has been shown to modify both membrane structures, and, either as primary or secondary effect, biomolecular functions.

To be successful in exploring this exciting field of science, a very close and highly interacting collaboration among biologists and physicists, biochemists and engineers is essential. Our team has eminent scientists in their respective fields of research from six academic institutions: Harvard/MIT Division of Health Sciences and Technology, Eastern Virginia Medical School, Old Dominion University, University of Texas Health Science Center at San Antonio, University of Wisconsin, and Washington University. The research facilities are designed for this kind of project, and are equipped with state-of-the-art research systems.

In a coherent, synergistic effort we will study the subcellular responses to narrowband and wideband radiofrequency radiation with frequency (distribution), power and exposure time as variable parameters, but such that the product of power and pulse duration, the energy, never exceeds values which let us expect nonthermal processes. We will use appropriate RF sources, ranging from cw to pulsed generators with one nanosecond exposure time, and we will thoroughly characterize the electric field and magnetic field distribution at the location of the irradiated samples. A lack of precision in design and characterization of the radiation source is assumed to be one of the major causes of non-reprodueable results reported in the literature. We will focus on one type of mammalian cell, which easily be grown and reproduced at any of the participating institutions, and which will serve as standard. In addition other cell types of interest, such as neural cells will be used for special studies.

Fluorescence microscopy methods will be used to determine the local value of electric field and temperature in the cells with a temporal resolution in the nanosecond range. Other imaging techniques include confocal microcopy and flow cytometry. The biomolecular analyses will include microarray analysis for changes in gene expression (mRNA studies), proteomics for changes in protein synthesis and protein modulation, signal transduction studies, studies on the effect of RF on binding of single-ligand receptors, cell proliferation studies, and studies on apoptosis induction. In both imaging and biomolecular analyses the focus will be on the nucleus and the mitochondrion. An important part of the research is modeling of RF interactions with cells. It provides guidance to the experimentalists, and in turn uses the experimental results to test and improve the model. New approaches to modeling and simulation will allow us to carry out progressively more realistic prediction of physical and chemical changes due to RF fields, for both wideband and narrowband radiation.

Communication between the researchers will be through monthly teleconferences, an annual workshop, possibly in connection with a conference, special sessions at relevant conferences, and "rotation" of graduate students and postdoctoral research associates. At three institutions short courses on topics, relevant for this project will be offered during the summer break to graduate students and other interested scientists. This "cross-training" of students and young, postgraduate researchers is not just important for this project, but for providing future experimentalists and theoreticians in this exciting field of bioelectromagnetics.

The results of these studies will be more than just a contribution to the knowledge base on bioelectromagnetic effects. They may lead to the development of novel sensitive detectors based on RF-induced changes in gene expression, and/or proteins. The search for nonthermal effects will lead to new and more sensitive diagnostic techniques, and might even lead to new therapeutic methods. The results of these studies will contribute to the verification or change of safety standards for occupational and military personnel, and for the general public. And, although these studies focus on effects in mammalian cells, any knowledge obtained on lethal effects of wideband RF irradiation might be applicable to bacterial decontamination.