EMF Dose Defined by Biology

Martin Blank, Ph.D.
Columbia University
New York City, NY

The scientific roots of bioelectromagnetics go back to the origins of modern science, but our 30 year old Society for the study of electromagnetic field (EMF) interactions with biological systems still has not properly defined a biological dose of EMF. This problem has impeded progress in understanding basic mechanisms, and it adds to the controversy about safety standards. We probably should have paid more attention to biology all along, instead of being guided almost entirely by electromagnetics. By tying our scientific discussions so closely to the divisions of the EM spectrum, we separated biology in the power (extremely low frequency, ELF) range from the same biology in the radio frequency (RF) range. As a result, we have two inconsistent measures of EMF dose in the ELF and RF ranges, and neither is related to biology.

In the ELF range, the EMF stimulus and implied dose is the flux density, measured in gauss and proportional to a force. In the RF range, it is the energy, or more precisely the rate of energy output/input (i.e., power) that is considered the dose. The rate of energy output/input is generally referred to as a thermal standard since the magnitudes are determined by the change in temperature. To complicate matters, the output is measured in W/cm2 and the input in W/kg, so the input rate varies with the mass, an additional source of ambiguity.

The thermal standard is clearly untenable as a measure of dose when EMF stimuli that differ by many orders of magnitude in energy can stimulate the same biological response. In the ELF range, the same biological changes occur as in the RF, and no change in temperature can even be detected. Despite overwhelming scientific evidence, there are those who oppose any attempt to correct the thermal standard.

The underemphasis on biology has also led to an undefined role of frequency in the biological response. We know that the divisions of the EM spectrum based on frequency are arbitrary and unrelated to biology, except for the special case of the visual range. There are optimal frequencies associated with the kinetics of the few electron transfer reactions studied, but in most biological studies, frequency does not appear to matter. With DNA interactions, the same biological responses are stimulated in ELF and RF ranges even though the frequencies of the stimuli differ by many orders of magnitude. The biology stimulated by the non-ionizing EMF can also be stimulated by higher frequencies in the ionizing range. The thermal mechanisms that are activated as EMF energy increases appear to be in addition to the low energy mechanisms. Analysis of the DNA in the promoter of a stress protein showed that different DNA sequences respond to EMF and thermal stimuli.

The effects of EMF on DNA to initiate the stress response or to cause molecular damage reflect the same biology in the different frequency ranges. For this reason, it should be possible to develop a scale based on DNA biology, and use it to define EMF dose in different parts of the EM spectrum. The stress response, EMF stimulation of DNA to initiate synthesis of stress proteins, is activated in both ELF and RF divisions of the EM spectrum, as well as in the ionizing range. We also see a continuous scale in DNA experiments that focus on molecular damage, where single and double strand breaks have long been known to occur in the ionizing range, and recent studies have shown similar effects in both ELF and RF ranges.

One can assess quantitatively the stress response or molecular damage as a measure of EMF dose over a large part of the EM spectrum, but DNA damage also makes possible a quantitative relation between EMF dose and disease. This can be done by utilizing the data banks that have been kept for A-bomb exposure and victims of nuclear accidents that link one time exposure to ionizing radiation and subsequent development of cancer. There are also data from experimental studies of DNA breaks with ionizing radiation that can be used to extend the scale relating cancer incidence to weaker EMF exposures. Many studies of DNA damage at different exposure intensities and durations for both non-ionizing and ionizing frequencies would be needed. Estimates of DNA repair rates would also be needed, especially to compare one time exposure with continuous and multiple exposures.

In practice, we should be able to determine the number of single and double strand breaks or micronuclei produced in a standard preparation of DNA of a given size, caused by exposure to EMF for a specified duration, under comparable conditions. Short durations would minimize the effect of intrinsic DNA repair mechanisms, but it would be better if the repair enzymes were inhibited. The assays are not easy; biological systems change in reaction to external stimuli. Nevertheless, it would be worth the effort if it leads to a quantitative relation between DNA damage and EMF exposure parameters (e.g., intensity, duration, frequency), in other words, a reliable measure of biological dose. Since the same DNA biology is activated in different parts of the EM spectrum, it should be possible to develop an unambiguous definition of EMF dose and a single scale for its measurement based on the biology.