The controversy continues regarding the interpretation and significance of biological changes that occur when a system is exposed to a multitude of combinations of static and oscillating electric and magnetic fields. Even when biological changes do occur, the implications regarding whether or not these changes also cause adverse health effects are not clear. Cellular and genetic studies continue to examine potential pathways and mechanisms to explain observed bioeffects, attempting to separate real effects from those due to chance. Observed bioeffects from application of EMF include: modulation of ion flows; interference with or enhancement of DNA synthesis and RNA transcription; modification of normal cell interaction with various biochemical agents; and interaction with the biochemical kinetics of cancer cells.
What has been lacking up to this point has been consistent replication of existing work. With the onset of the Department of Energy's (DOE) Research and Public Information Dissemination, or RAPID program, however, replication studies are now considered worthy of funding. In fact, Imre Gyuk of the DOE took the opportunity at one of the paper presentations to announce a new initiative undertaken by both DOE and the National Institute for Environmental Health Sciences (NIEHS). A new series of laboratory facilities will be available for researchers to use as a means to promote not only replication in laboratory studies, but also to promote the use of uniform experimental conditions.
Probably the most significant preliminary data to emerge from the conference were identification of two new endpoints: Alzheimer's disease and lung cancer - both as possible outcomes related to occupational exposure to electric and magnetic fields. Alzheimer's disease is a slow degenerative mental disorder affecting millions of predominantly older Americans and costing approximately $82 billion per year. Eugene Sobel, an epidemiologist with the University of Southern California, Los Angeles, and other researchers did not expect to find a high association between incidence of the disease and the occupations of seamstress and tailor. However, the odds ratios reported for three different data sets were elevated, when reported separately, and significantly so when reported as a combined data set. For women, the combined odds ratio of developing Alzheimer's disease working as a seamstress or tailor is 3.8, with 95% confidence interval (CI) of 1.7 to 8.6. For both sexes combined the odds ratio was 3.0 (1.6, 5.4). For men the odds ratio was 2.1, but with 95% CI (0.8, 5.2), it was not statistically significant. After-the-fact magnetic field measurements revealed average levels of 65 milliGauss (mG) for industrial sewing machines (19.5 mG for home sewing machines) as compared to the average magnetic fields experienced by a utility lineworker of around 23 mG. His work presented in November is currently in press for Science.
With the primary focus on leukemia and brain cancer, lung cancer has only sporadically been evaluated as a possible endpoint with exposures to EMF. However, results presented by Gilles Theriault et al (McGill University) reveal that there is a 3-fold risk of developing lung cancer in Canadian utility workers, with a 6.67-fold increase in risk for those in the highest exposure group. The association was not explained by smoking or other occupational exposures. Characterization of the high frequency transient channel of the dosimeters used in this study revealed that a pulsed electromagnetic field (PEMF) was measured at frequencies between 10 Megahertz(MHz) - 400 MHz, frequencies associated with the use of walkie-talkie radios commonly used by utility workers. [Note: This study was published in the November 1, 1994 edition of the American Journal of Epidemiology.] Although this study is not pertinent to the 60-hertz low frequency EMF associated with transmission lines, it is expected that this will add to the concerns of the public pertaining to various parts of the electromagnetic energy spectrum.
Another preliminary study of note was undertaken by Dr. Susan Preston-Martin (University of Southern California). She and colleagues addressed the question: Are brain tumors in children related to residential exposure to magnetic fields? With a preliminary evaluation of the data, the investigators found no increased risk of brain tumors in children whose homes were identified as having high current wiring configuration.
The next EMF research conference is scheduled for June 1995 with the annual Bioelectromagnetics Society meeting in Boston.