Induced current measurements in whole body exposure condition to radio frequency electric fields.

The current induced in a human exposed to radio frequency electric fields has been studied by the use of a stripline, in which whole body exposure to vertical electric fields (3-27 MHz) can be produced. We have examined two different techniques to measure the induced current; parallel plate meters and current probes. When the subject has good connection to the ground, the choice of measurement technique is not crucial, since there are only minor differences in readings between the instruments. But when the subject is wearing shoes and/or standing on a wooden plate, the difference between the instruments increases considerably. The difference can mainly be explained by the capacitive coupling between the parallel plate meters and the ground; therefore, the current probes are preferred when the subject does not have perfect contact with the ground. Since the International Commission on Non-Ionizing Radiation Protection guidelines demand measurements of induced current in humans exposed to radio frequency fields in the range of 10-110 MHz, the importance of finding an appropriate measurement procedure becomes apparent.

A 50-Hz electromagnetic field impairs sleep.

In view of reports of health problems induced by low frequency (50-60 Hz) electromagnetic fields (EMF), we carried out a study in 18 healthy subjects, comparing sleep with and without exposure to a 50 Hz/1 mu Tesla electrical field. We found that the EMF condition was associated with reduced: total sleep time (TST), sleep efficiency, stages 3 + 4 slow wave sleep (SWS), and slow wave activity (SWA). Circulating melatonin, growth hormone, prolactin, testosterone or cortisol were not affected. The results suggest that commonly occurring low frequency electromagnetic fields may interfere with sleep.

DNA damage, cell kinetics and ODC activities studied in CBA mice exposed to electromagnetic fields generated by transmission lines.

CBA mice were exposed outdoors to 50 Hz electromagnetic fields (EMF), with a flux density of about 8 microT rms (root mean square), generated by a 220 kV transmission line. Assays were performed in order to investigate, the possible genotoxic effects after 11, 20 and 32 days of exposure, as well as the effects on body weight, leukocytes, erythrocytes, and the level of ornithine decarboxylase (ODC) activity in spleen and testis. DNA migration was studied on brain cells by single cell electrophoresis (comet assay). After 32 days of exposure a highly significant change of the tail/head ratio of the comets was observed (p < 0.001), showing DNA-damage. Further, a decreased number of mononuclear leukocytes (0.02 < p < 0.05) was observed in mice EMF-exposed for 20 days. In summary, our data indicate that transmission lines of this type may induce genotoxic effects in mice, seen as changes in the DNA migration. These results might have an important implication for health effects.

Exposure to extremely low frequency electromagnetic fields and the risk of malignant diseases--an evaluation of epidemiological and experimental findings.

Epidemiological and experimental studies concerning extremely low frequency electromagnetic field exposure and malignant diseases published up to 1 July 1994 were evaluated to assess the possible carcinogenicity of electromagnetic fields and the scientific basis for environmental and occupational standard setting. We concluded that there are possible associations between (i) an increased risk of leukaemia in children and the existence of, or distance to, power lines in the vicinity of their residence, (ii) an increased risk of chronic lymphatic leukaemia and occupational exposure to low frequency electromagnetic fields and (iii) an increased risk of breast cancer, malignant melanoma of the skin, nervous system tumours, non-Hodgkin lymphoma, acute lymphatic leukaemia or acute myeloid leukaemia and certain occupations. There is no scientific basis for occupational or environmental standard setting for low frequency electric or magnetic fields.

Intraocular light scattering in vision, artistic painting, and photography.

Light scattering in the eye is reviewed, and its influence on vision is discussed in some detail. Isotropic scattering and formation of halos around point sources are described with reference to theory and experiments. Artists usually take intraocularly scattered light into account when painting natural scenes. A method to achieve similar effects in photography by the use of diffraction filters in front of the camera lens is demonstrated. A number of photos that illustrate the effects of such filters are shown.

Effects of pulsed magnetic fields on the developing mouse embryo.

The influence of a pulsed magnetic field (PMF; sawtooth with 45-microseconds linear rise time and 5-microseconds decay time, peak strength of 15 microT, and frequency 20000 pps) [corrected] on the embryogenesis of CBA/S mice was investigated in five experiments based on a total of 707 exposed and 543 unexposed primigravidas. Sham and PMF exposures began on day 1 of gestation (experiments 1 and 2), on day 2 (experiment 3), on day 5 (experiment 4), and on day 7 (experiment 5); all exposures continued until day 19 post conception (p.c.), when they were terminated, at which time the following variables were measured: number of implants; number of placental resorptions; number of living fetuses; number of dead fetuses; number of malformations in living and dead fetuses; and length and body mass of living fetuses. Control dams were sham-exposed concurrently with corresponding, PMF-exposed dams. With the exception of experiment 5, in which exposure to PMF started on day 7 p.c., all groups of exposed mice had significantly more placental resorptions when compared with concurrent controls. The increased resorption rate was not reflected in a reduction in litter size or in the number of litters. A significant increase in malformed fetuses was not seen in any of the exposed groups, or when groups were pooled. Only in experiment 1 was the number of dead fetuses affected by exposure to PMF. The effect of PMF on the implantation rate was not significant. Body mass and length of exposed fetuses were significantly reduced only when the PMF treatment began on day 7 p.c.(ABSTRACT TRUNCATED AT 250 WORDS)

Contrast sensitivity in the presence of a glare light. Theoretical concepts and preliminary clinical studies.

A method is presented for quantitative measurements of the glare effect of light scattered in the ocular media. The contrast sensitivity function is measured with a television display system. A bright light source is introduced into the field of vision, and the resultant decrease in contrast sensitivity is mea-ured. It is further used to calculate a scattering factor which is a direct measure of the intraocular light scattering. The scattering factor shows a marked increase in patients with early cataracts even if their visual acuity is not affected.

Retinal damage experimentally induced by microwave radiation at 55 mW/cm2.

The action of 550 W/m2 (mean) 3100 MHz pulsed radiation on the rabbit retina in vivo was investigated by fundus photography, blood-retinal barrier tracers, light and electron microscopy, either after a single 1--1.5 h exposure or after a series of repeated 1 h exposures for up to 53 h during about 100 days. The electron microscopic investigation of the repeatedly exposed retinas revealed degenerative changes in the retinal neurons. The neurons appeared depleted of their cytoplasmic constituents and often contained phago-lysosomal structures with myelin bodies. There were many degenerating synaptic boutons. The glial cells displayed reactive changes. These ultrastructural changes could not be demonstrated by the other methods used. A single microwave exposure, followed by an induced 70--100% blood-pressure increase, did not enhance blood-retina barrier permeability to tracers. There was no evidence of blood brain barrier leakage. These studies show that the rabbit eye can be affected by microwave radiation at intensities lower than previously reported.