Effect of electromagnetic interference by neonatal transport equipment on aircraft operation.

The number of civilian air ambulance services operating in the United States has been steadily increasing. The quantity and sophistication of electronic equipment used during neonatal transport have also increased. All medical equipment generates some electromagnetic interference (EMI). Excessive EMI can interfere with any of an aircraft's electrical systems, including navigation and communications. The United States military has strict standards for maximum EMI in transport equipment. Over the past 15 years, approximately 70% of neonatal transport monitors, ventilators, and incubators have failed testing due to excessive EMI. As neonatal transport equipment becomes more sophisticated, EMI is increased, and there is greater potential for aircraft malfunction. The Federal Aviation Administration should develop civilian standards for acceptable EMI, civilian aircraft operators must be aware of the possible dangers of excessive EMI, and equipment which does not meet future FAA standards should not be purchased.

An evaluation of the existing evidence on the carcinogenic potential of extremely low frequency magnetic fields.

The existing evidence suggesting a link between exposure to Extremely Low Frequency (ELF) magnetic fields and an increased incidence of cancer is reviewed and evaluated.

Effects of noise and electromagnetic fields on reproductive outcomes.

Much public health research has been directed to studies of cancer risks due to chemical agents. Recently, increasing attention has been given to adverse reproductive outcomes as another, shorter-term biologic indicator of public health impact. Further, several low-level ubiquitous physical agents have been implicated recently as possibly affecting human health. These physical factors (noise and electromagnetic fields) represent difficult topics for research with epidemiologic study methods. This paper provides a brief review of the published data related to the risk of adverse reproductive outcomes and exposure to noise or electromagnetic fields. The discussion includes ideas for possible biologic mechanisms, considerations for exposure assessment, and suggestions for epidemiologic research.

DNA repair after gamma irradiation in lymphocytes exposed to low-frequency pulsed electromagnetic fields.

The effect of exposure to extremely low-frequency pulsed electromagnetic fields (EMFs) on DNA repair capability and on cell survival in human lymphocytes damaged in vitro with gamma rays was studied by two different micromethods. In the first assay, which measures DNA repair synthesis (unscheduled DNA synthesis, UDS), lymphocyte cultures were stimulated with phytohemagglutinin (PHA) for 66 h and then treated with hydroxyurea (which blocks DNA replication), irradiated with 100 Gy of 60Co, pulsed with [3H]thymidine ([3H]TdR), and then exposed to pulsed EMFs for 6 h (the period in which cells repaired DNA damage). In the second assay, which measures cell survival after radiation or chemical damage, lymphocytes were first irradiated with graded doses of gamma rays or treated with diverse antiproliferative agents, and then stimulated with PHA, cultured for 72 h, and pulsed with [3H]TdR for the last 6 h of culture. In this case, immediately after the damage induced by either the radiation or chemicals, cultures were exposed to pulsed EMFs for 72 h, during which cell proliferation took place. Exposure to pulsed EMFs did not affect either UDS or cell survival, suggesting that this type of nonionizing radiation--to which humans may be exposed in the environment, and which is used for both diagnostic and therapeutic purposes--does not affect DNA repair mechanisms.

[The effect of a high-frequency electromagnetic field (2.45 GHz) on perceptual processes, psychological performance and well-being]. / Die Wirkung eines höchstfrequenten elektromagnetischen Feldes (2,45 GHz) auf Wahrnehmungsprozesse, psychische Leistung und Befinden.

In a sample of 8 male subjects the effect of an ultra-highfrequency electromagnetic field (f = 2.45 GHz) with power densities of 1,000, 500 and 100 microW/cm2 was investigated. As parameters were used the perceptional threshold in a tachistoscopic perceptional test, the total time from the numbersearch-test and the sum of acute symptoms and complaints measured by a special questionnaire. At the highest field intensity on the one side increases of the total times and of the sum of complaints occurred. The differential threshold increased distinctly under 500 microW/cm2 exposure, whereas the total times and the sum of symptoms were not affected. At the lowest power density no differences between exposure and nonexposure conditions have been found. The intraindividual variability was considerable.

Pacemaker function during helicopter transport.

A 71-year-old man had an increased pacemaker firing rate during helicopter transport. The increased rate, which resolved as soon as the engines were shut down, was thought to be due to the vibrations of the helicopter. We discuss the effect of vibration and electromagnetic force generated during helicopter transport on pacemakers. As the number of patients transported by air ambulances increases, the potential sequela must be recognized.

[Magnetic field on the deranged accommodation of visual detector terminal operators].

The effects of magnetic fields on the accommodation of operators engaged in visual display terminals (VDT) who complained of asthenopia and proved to have some abnormalities in the semistastic properties of accommodation were examined. Before and after loading a magnetic field of 400 Gauss or 2,000 Gauss on the eye, the quasistatic properties of accommodation were measured and compared. The quasistastic properties analyzed in this experiment were the maximum amplitude of accommodation and the gradient of accommodation that means a ratio of accommodative response to accommodative stimulus. Both factors were statistically improved in a dose dependent manner after loading the magnetic field, i.e. 2,000 Gauss was more effective than 400 Gauss concerning the improvement of accommodation. To exclude a psychogenic effects, simulated loading by a placebo which was an imitation magnet which did not produce a magnetic field was also applied to the patients, but no improvement was detected. Normal persons who were examined as controls showed no statistical change in the semistastic properties of accommodation after loading of the magnetic field. After examination of the semistatic properties of accommodation, refraction was also estimated by an autorefractometer, but no change was detected in either patients or controls. The magnetic field seemed definitely to have effects on the functionally involved accommodative system.

Proportionality of 60-Hz electric field bioeffect severity to average induced transmembrane potential magnitude in a root model system.

The postulate that electric field-induced bioeffects in the root model system are related to the induction of 60-Hz transmembrane potentials (Vim) was quantitatively tested. Root segment growth rate data and the calculated mean 60-Hz Vim which would arise in the cortical cells of a segment under specified exposure conditions were subjected to regression analysis. Statistically significant correlations between segmental growth rate and segmental-average Vim were obtained using data analyzed (1) within species at a constant applied field strength, (2) within species and pooled across field exposures, and (3) pooled across both species and exposures. In C. sativus roots, segmental growth is inhibited when segmental-average Vim attain a value of 3.4-3.6 mV. In C. maxima roots, growth inhibition occurs when Vim attain or exceed 2.3-2.7 mV. Segmental growth cessation is predicted to occur when segmental-average Vim exceed 7-9 mV.

Chronic exposure of primates to 60-Hz electric and magnetic fields: II. Neurochemical effects.

We exposed Macaca nemestrina (pig-tailed macaques) to electric (E) and magnetic (B) fields ranging in intensity from 3 kV/m and 0.1 G to 30 kV/m and 0.9 G for three 21-day (d) periods. Experimental animals were exposed to sham E and B fields for two 21-d periods, one prior to and one following actual exposure to E and B fields, resulting in a total of five 21-d periods. Control animals were exposed to sham E and B fields for the entire 105-d interval. At the end of each 21-d period cerebrospinal fluid (CSF) was obtained by lumbar puncture and analyzed for concentrations of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA), metabolites of dopamine and serotonin neurotransmitters, respectively, by high-performance liquid chromatography with electrochemical detection (HPLC-ECD). Results are based on an examination of six experimental and four control animals. Exposure to E and B fields at all strengths was associated with a significant decline in CSF concentrations of both HVA and 5-HIAA when statistical comparisons were made against values obtained at the end of the preexposure interval. However, HVA returned to preexposure levels during the postexposure period, while 5-HIAA did not. No significant change in the concentrations of HVA or 5-HIAA was noted in the control animals. These results strongly suggest that exposure of the nonhuman primate to E and B fields can significantly affect specific biochemical estimates of nervous system function. These effects may involve alterations either in neuronal activity or in the activity of enzymes that catabolize the neurotransmitters.

Intensity threshold for 60-Hz magnetically induced behavioral changes in rats.

Experiments were conducted to further investigate the effect of 60-Hz cyclotron-resonance exposures on rats performing on a multiple FR-DRL schedule. The previously reported temporary loss of DRL baseline response, when measured as a function of A.C. magnetic intensity, was found to have a threshold. Utilizing the component of A.C. magnetic intensity parallel to the D.C. field, we report this threshold as (0.27 +/- 0.10) x 10(-4) Trms.

Ambient 60-Hz magnetic flux density in an urban neighborhood.

A residential neighborhood in Buffalo, NY, was surveyed with a magnetic field meter to evaluate whether or not spot measurements are reliable predictors of the 60-Hz fields at street corners and residences. The results of repeated measurements over 7 days at 33 street corners in this neighborhood indicate that day-to-day variation in power line magnetic fields is negligible (intraclass correlation coefficient = 0.94). Multivariate linear regression analysis of the data indicates that transmission lines and thick, three-phase primary wires near the field measurement site are strong predictors and account for the majority of the ambient magnetic field variance between locations (multiple correlation coefficient squared = 0.60; F ratio = 22.2, P less than .001). Magnetic fields measured at the front sidewalk were highly correlated with fields at the front doorsteps of 45 homes in this neighborhood (gamma = 0.81). These results suggest that ambient power line magnetic field levels at urban residences can be reliably characterized on a one-time site inspection using a hand-held magnetic field meter and a simple wiring classification system.

Chronic exposure of primates to 60-Hz electric and magnetic fields: I. Exposure system and measurements of general health and performance.

We exposed pigtailed macaques (Macaca nemestrina) to electric (E) and magnetic (B) fields at strengths of 3 kV/m and 0.1 G, 10 kV/m and 0.3 G, and 30 kV/m and 0.9 G for three 21 day segments. These three exposure segments were preceded and followed by 21 day sham exposure segments. Additional animals received only sham exposure for five 21 day segments. Detailed description of the exposure chamber and field generation apparatus is given. We evaluated measures of animal well-being, including weight, blood chemistry, blood cell counts, and performance on a simple motor task, and performed postmortem examinations. Reliable and consistent results were obtained throughout data collection. None of the measures evaluated was significantly affected by E- and B-field exposures. Data obtained during actual exposure segments were not distinguishable from those obtained during the initial and final sham exposure segments, nor were they different from data obtained from the sham-exposed animals. Thus, field exposure had no apparent effects on general health or performance.

Chronic exposure of primates to 60-Hz electric and magnetic fields: III. Neurophysiologic effects.

The neurophysiologic effects of combined 60-Hz electric (E) and magnetic (B) fields, of magnitudes comparable to those produced by high-voltage powerlines, were investigated in 10 monkeys (Macaca nemestrina). Six animals (experimental group) were each exposed to three different levels of E and B fields: 3 kV/m and 0.1 G, 10 kV/m and 0.3 G, and 30 kV/m and 0.9 G. Field exposures were preceded and followed by sham exposures, during which factors of field generation were present (e.g., heat, vibration, noise, etc.) without E and B fields. Each of the five segments (i.e., the three exposure segments and the initial and final sham exposure segments) lasted 3 weeks. Animals were exposed for 18 h/day (fields on at 1600 h, off at 1000 h). Four other animals (external control group) were given sham exposure for the entire 15-week period. Auditory, visual, and somatosensory evoked potentials were recorded twice a week, during the daily 6-h field-off period. E- and B-field exposure had no effect on the early or mid-latency evoked potential components, suggesting that exposure at these levels has no effect on peripheral or central sensory afferent pathways. However, there was a statistically significant decrease in the amplitudes of late components of the somatosensory evoked potential during the 10kV/m and 0.3 G, and 30 kV/m and 0.9 G exposure levels. This result is possibly related to the opiate antagonist effect of electromagnetic field exposure reported by others.

Fetal loss associated with two seasonal sources of electromagnetic field exposure.

We have studied two sources of electromagnetic fields where exposure is highly seasonal (ceiling cable electric heat and electrically heated beds). Because many potential confounders could not be addressed, we can make no valid statement about overall differences in abortion rates between those exposed and those not exposed to these seasonal sources. However, by analyzing seasonal trends, we have minimized the problem of unaddressed confounders because we did not look at a difference between the user and nonuser groups, but rather at a difference within the user group during months of higher exposure compared with months of lower exposure. Thus, each user group provides its own control. The function of the nonuser control group is simply to assure that any seasonal trend found in the user group is not just a general seasonal variation in reported fetal loss that can be found equally well in the nonuser population. Using this technique, we found that each user group reported fetal loss disproportionately often during the season when electromagnetic field exposure was increasing.

Geophysical variables and behavior: LIII. Epidemiological considerations for incidence of cancer and depression in areas of frequent UFO reports.

Luminous phenomena and anomalous physical forces have been hypothesized to be generated by focal tectonic strain fields that precede earthquakes. If these geophysical processes exist, then their spatial and temporal density should be greatest during periods of protracted, localized UFO reports; they might be used as dosimetric indicators. Contemporary epidemiological data concerning the health risks of power frequency electromagnetic fields and radon gas levels (expected correlates of certain tectonic strain fields), suggest that increased incidence (odds ratios greater 1:3) of brain tumors and leukemia should be evident within "flap" areas. In addition the frequency of variants of temporal lobe lability, psychological depression and posttraumatic stress should be significantly elevated. UFO field investigators, because they have repeated, intermittent close proximity to these fields, are considered to be a particularly high risk population for these disorders.