Study type: Medical/biological study (experimental study)

Chronic electromagnetic field exposure decreases HSP70 levels and lowers cytoprotection. med./bio.

Published in: J Cell Biochem 2002; 84 (3): 447-454

Aim of study (acc. to author)

Chick embryos were either continuously or repeatedly exposed to extremely low frequency or radiofrequency electromagnetic fields to assay for HSP70 induction or survival following hypoxia/re-oxygenation insult.

Background/further details

It was hypothesized that de-protection against hypoxia should occur following long-term, continuous, or daily, repeated exposures to electromagnetic fields.
Experiments are based on a study in which long-term (4 days), continuous exposure to extremely low frequency electromagnetic fields decreased protection against ultraviolet radiation.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 60 Hz
Exposure duration: continuous for 30 min or 4 days, or repeated daily exposure for 20, 30 or 60 min, once or twice daily, for 4 days
Exposure 2: 915 MHz
Exposure duration: continuous for 30 min, or repeated daily exposure, 30 or 60 min/day, for 4 days

General information

Positive control embryos were heated by placing eggs into plastic bags and submerging them in a 43°C water bath for 60 min. Other samples were heated at 39 or 41°C for 30 min to mimic the heating which might occur during an RF-EMF exposure.

Exposure 1

Main characteristics
Frequency 60 Hz
Type
Waveform
  • unspecified
Exposure duration continuous for 30 min or 4 days, or repeated daily exposure for 20, 30 or 60 min, once or twice daily, for 4 days
Exposure setup
Exposure source
Chamber Fields were produced by paired Helmholtz coils, wound and connected as described previously with slight modification [Berman et al., 1990]. A coil diameter of 15 inches provided a region of nearly uniform magnetic field (±5%). Six paired Helmholtz coils were housed in water-jacketed incubators maintained at 37.8°C. Up to 24 embryos (in shells) could be exposed at a time.
Setup Helmholtz coils were wired such that one coil could produce a cancelled field while the other coil produced a 60 Hz field. Thus, control (sham-exposed) embryos received no field exposure, but did experience all other environmental conditions (e.g., generation of heat or vibration) that might be produced by an activated coil.
Additional info In some experiments, random ELF-EMF noise (band width 30-90 Hz, 8 µT) produced by a random noise generator, incorporated into an audio amplifier, was superimposed using the Helmholtz coils as described above.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 8 µT - measured - -

Exposure 2

Main characteristics
Frequency 915 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 30 min, or repeated daily exposure, 30 or 60 min/day, for 4 days
Modulation
Modulation type unspecified
Exposure setup
Exposure source
Chamber The Crawford cell having two sample chambers located on either side of the center conductor, and a double stub tuner was mounted vertically on a rotary table installed inside an incubator chamber maintained at 37.5°C.
Setup Up to eight embryos (in shells) could be exposed simultaneously. Control embryos were placed outside the Crawford cell.
Additional info Thermocouple readings indicated that the temperature increase of the embryo was less than 0.6 or 1.2°C during the 30 or 60 min exposures, respectively (to below 39.0°C final temperature). In some experiments, random ELF-EMF noise (band width 30-90 Hz, 8 µT) produced by a random noise generator, incorporated into an audio amplifier, was superimposed using the Helmholtz coils as described above.
Parameters
Measurand Value Type Method Mass Remarks
power 3.5 W - - - -
SAR 1.7 W/kg - calculated - -

Reference articles

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

Several of the exposure protocols yielded embryos that had statistically significant decreases in protection against hypoxic stress (continuous exposure and 30 or 60 min extremely low frequency (twice daily); or 30 or 60 min once daily radiofrequency). This is consistent with the result that following 4 days of extremely low frequency electromagnetic field exposure, HSP70 levels declined by 27% as compared to controls. In addition, the superposition of extremely low frequency electromagnetic field noise inhibited hypoxia de-protection caused by long-term, continuous extremely low frequency or daily, repeated radiofrequency exposures.
This electromagnetic field-induced decrease in HSP70 levels and resulting decline in cytoprotection suggests a mechanism by which daily exposure (such as might be experienced by mobile phone users) could enhance the probability of cancer and other diseases.

Study character:

Study funded by

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