Medical/biological study (experimental study)

Bioeffects induced by exposure to microwaves are mitigated by superposition of ELF noise med./bio.

By: Litovitz TA, Penafiel LM, Farrel JM, Krause D, Meister R, Mullins JM

Published in: Bioelectromagnetics 1997; 18 (6): 422-430

Aim of study (acc. to author)

The authors speculated that the superimposition of electromagnetic noise fields, which have been shown to inhibit biological responses due to extremely low frequency exposure (see publication 344 and publication 2809), may also inhibit the effects of modulated microwaves.
The aim of the study was to investigate this possibility by conducting experiments in which biological samples were exposed concurrently to amplitude modulation and extremely low frequency noise fields.

Exposure	Parameters
Exposure 1: 835 MHz Modulation type: AM Exposure duration: continuous for 8 h	power: 1 W mean electric field strength: 1 V/cm mean SAR: 2.5 W/kg mean
Exposure 2: 840 MHz Modulation type: pulsed Exposure duration: continuous for 8 h	power: 1 W mean (peak power of 3.8 W) electric field strength: 1 V/cm mean SAR: 2.5 W/kg mean
Exposure 3: 30–100 Hz Exposure duration: continuous for 8 h	magnetic flux density: 4 µT effective value (0.25, 0.5, 1, 2 and 4 µT concurrent with E1) magnetic flux density: 10 µT effective value (1, 2, 5 and 10 µT concurrent with E2)

General information

The ELF/MW exposure system was designed for concurrent exposure to ELF and MW fields. Controls were performed concurrently inside a separate incubator at 37°C. The four flasks were stacked one on top of another and covered with a 12.7 cm x 7.6 cm x 8.9 cm mil-annealed mu-metal enclosure which was, however, not fully sealed against its base.

Exposure 1

Main characteristics

Frequency	835 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 8 h

Modulation

Modulation type	AM
Modulation frequency	60 Hz
Modulation depth	23 %
Additional info	sinusoidal

Exposure setup

Exposure source	Helmholtz coils TEM cell signal generator
Chamber	The Crawford cell having two chambers and a double stub tuner was mounted vertically on a rotary table positioned within a pair of Helmholtz coils installed inside a water-jacketed incubator maintained at 37°C. The detailed arrangement of this exposure system has been described in the reference article.
Setup	Four 25 cm² tissue culture flasks, each containing 5 ml of culture medium, were placed as pairs, end to end, on either side of the center conductor, flat on non-conducting shelves located at approx. 7 cm from the junction between the center rectangular section and the lower tapered end. The MW EF was perpendicular to the direction of propagation which was parallel to the long axis of the exposure chamber.
Additional info	There was no measurable temperature increase in the samples over the exposure period.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power	1 W	mean	measured	-	-
electric field strength	1 V/cm	mean	calculated	-	-
SAR	2.5 W/kg	mean	measured	-	-

Additional parameter details

Background 60 Hz MF was below 0.16 µT for exposed samples and below 0.04 µT for control samples.

Measurement and calculation details

The SAR distribution for this exposure arrangement has been reported in the reference article. The average SAR was calculated from point measurements taken on a pair of flasks on one side of the center conductor because the configuration was symmetric.

Exposure 2

Main characteristics

Frequency	840 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 8 h

Modulation

Modulation type	pulsed
Pulse width	7 ms
Duty cycle	33 %
Repetition frequency	50 Hz
Additional info	D-AMPS, pseudo-random test sequence in TDMA mode

Exposure setup

Exposure source	cellular phone Helmholtz coils TEM cell

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power	1 W	mean	measured	-	peak power of 3.8 W
electric field strength	1 V/cm	mean	calculated	-	-
SAR	2.5 W/kg	mean	measured	-	-

Exposure 3

Main characteristics

Frequency	30–100 Hz
Type	magnetic field
Exposure duration	continuous for 8 h
Additional info	ELF noise MF superimposed on E1 and E2

Modulation

Modulation type	cf. additional info
Additional info	AC field with random amplitude variations in time

Exposure setup

Exposure source	Helmholtz coils TEM cell noise generator
Chamber	In order to ensure a uniform MF, the coils were positioned so that the sample flasks placed in the Crawford cell were contained within a 12.7-cm cylinder with its axis parallel to the axis of the coils. The calculated attenuation of the ELF MF due to eddy currents was 0.08 dB which means that the Crawford cell should be nearly transparent to the ELF MF.
Setup	The coils consisting of 10 turns of 26-gauge magnet wire wound on a support ring made of hard plastic tubing had a diameter of 46 cm and a separation of 23 cm and were assembled on a Plexiglas frame positioned around the Crawford cell. The ELF MF was parallel to the base of the flasks so that the ELF EF induced in the cells was parallel to the MW EF. The ELF noise MF was generated using a custom made band limited noise generator connected to the coils via an audio amplifier.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	4 µT	effective value	measured	-	0.25, 0.5, 1, 2 and 4 µT concurrent with E1
magnetic flux density	10 µT	effective value	measured	-	1, 2, 5 and 10 µT concurrent with E2

Measurement and calculation details

The applied ELF MF was measured at a fixed location using a 10.2 cm, 200-turn pick-up coil. The rms value of the noise field was determined using an integration time of approx. 60 s. The ELF MF measured in the sample area using a 1.27 cm, 400-turn pick-up coil was found to vary by less than ±2%.

Reference articles

Litovitz TA et al. (1993): The role of coherence time in the effect of microwaves on ornithine decarboxylase activity

Exposed system:

intact cell/cell culture
murine L929 fibroblast cells

Methods Endpoint/measurement parameters/methodology

cell function: enzyme activity (ornithine decarboxylase activity; measurement of the release of ¹⁴CO₂ from ¹⁴C-labelled l-ornithine)

Investigated system:

isolated bio./chem. substance

Time of investigation:

after exposure

Main outcome of study (acc. to author)

In both cases, the ornithine decarboxylase activity enhancement was found to decrease exponentially as a function of the noise root mean square amplitude: With 60 Hz amplitude modulated microwaves, complete inhibition (of ornithine decarboxylase enhancement effect) was obtained with noise levels at or above 2 µT. With the DAMPS digital cellular phone signal, complete inhibition occurred with noise levels at or above 5 µT.
These findings suggest a possible practical means to inhibit biological effects from exposure to both extremely low frequency and microwave fields.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

EMX Corporation, USA
The Catholic University of American Research Fund

Replication studies

Billaudel B et al. (2009): Effects of exposure to DAMPS and GSM signals on ornithine decarboxylase (ODC) activity: I. L-929 mouse fibroblasts
Höytö A et al. (2007): Ornithine decarboxylase activity of L929 cells after exposure to continuous wave or 50 Hz modulated radiofrequency radiation--a replication study

Sun W et al. (2010): Superimposition of an Incoherent Magnetic Field Eliminated the Inhibition of Hormone Secretion Induced by a 50-Hz Magnetic Field in Human Villous Trophoblasts in vitro
Billaudel B et al. (2009): Effects of exposure to DAMPS and GSM signals on ornithine decarboxylase (ODC) activity: I. L-929 mouse fibroblasts
Billaudel B et al. (2009): Effects of exposure to DAMPS and GSM signals on ornithine decarboxylase (ODC) activity: II. SH-SY5Y human neuroblastoma cells
Yao K et al. (2008): Electromagnetic noise inhibits radiofrequency radiation-induced DNA damage and reactive oxygen species increase in human lens epithelial cells
Höytö A et al. (2007): Ornithine decarboxylase activity is affected in primary astrocytes but not in secondary cell lines exposed to 872 MHz RF radiation
Höytö A et al. (2007): Ornithine decarboxylase activity of L929 cells after exposure to continuous wave or 50 Hz modulated radiofrequency radiation--a replication study
Höytö A et al. (2006): Modest increase in temperature affects ODC activity in L929 cells: Low-level radiofrequency radiation does not
Penafiel LM et al. (1997): Role of modulation on the effect of microwaves on ornithine decarboxylase activity in L929 cells
Litovitz TA et al. (1994): Temporally incoherent magnetic fields mitigate the response of biological systems to temporally coherent magnetic fields
Litovitz TA et al. (1994): Superimposing spatially coherent electromagnetic noise inhibits field-induced abnormalities in developing chick embryos
Litovitz TA et al. (1991): Effect of coherence time of the applied magnetic field on ornithine decarboxylase activity
Byus CV et al. (1988): Increased ornithine decarboxylase activity in cultured cells exposed to low energy modulated microwave fields and phorbol ester tumor promoters
Byus CV et al. (1987): The effects of low-energy 60-Hz environmental electromagnetic fields upon the growth-related enzyme ornithine decarboxylase

Bioeffects induced by exposure to microwaves are mitigated by superposition of ELF noise med./bio.

Aim of study (acc. to author)

Background/further details

Endpoint

Exposure

General information

Exposure 1

Main characteristics

Modulation

Exposure setup

Parameters

Additional parameter details

Measurement and calculation details

Exposure 2

Main characteristics

Modulation

Exposure setup

Parameters

Exposure 3

Main characteristics

Modulation

Exposure setup

Parameters

Measurement and calculation details

Reference articles

Methods Endpoint/measurement parameters/methodology

Main outcome of study (acc. to author)

Study funded by

Replication studies

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