Medical/biological study (experimental study)

Ornithine decarboxylase activity of L929 cells after exposure to continuous wave or 50 Hz modulated radiofrequency radiation--a replication study med./bio.

By: Höytö A, Juutilainen J, Naarala J

Published in: Bioelectromagnetics 2007; 28 (7): 501-508

Aim of study (acc. to author)

A replication study with some extensions was made to confirm enhancement of ornithine decarboxylase enzyme activity in murine L929 fibroblasts after radiofrequency electromagnetic field exposure reported in earlier studies (publication 1718 and publication 3382).

Background/further details

L929 cells purchased from two cell banks were exposed for 2, 8, or 24 h to continuous wave or D-AMPS signal. In positive control experiments, medium change was used to induce and serum deprivation to suppress ornithine decarboxylase activity.

Endpoint

cell function: enzyme activity (ornithine decarboxylase)

Exposure

- TDMA
- mobile communications
- digital mobile phone
- D-AMPS

Exposure	Parameters
Exposure 1: 835 MHz Modulation type: CW Exposure duration: continuous for 2, 8, or 24 h	SAR: 2.5 W/kg SAR: 6 W/kg
Exposure 2: 835 MHz Modulation type: pulsed Exposure duration: continuous for 2, 8, or 24 h	SAR: 2.5 W/kg SAR: 6 W/kg
Exposure 3: 872 MHz Modulation type: pulsed Exposure duration: continuous for 8 h	SAR: 6 W/kg

General information

RF and sham exposures were carried out in Crawford chambers and in waveguide exposure chambers. In sham-sham experiments, cell flasks or dishes were placed in both exposure chambers, and no RF field was applied.

Exposure 1

Main characteristics

Frequency	835 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 2, 8, or 24 h

Modulation

Modulation type	CW

Exposure setup

Exposure source	TEM cell
Chamber	The Crawford chambers were housed in a water jacketed CO₂ incubator. Compared to the design used by Penafiel et al. [1997], a few modifications were made to improve the setup: The doors were enlarged, shelves were added inside, power sensors were fitted, and ventilators were introduced. These improvements increased the accuracy and reproducibility of exposures.
Setup	Cells seeded into two sealed 25 cm² plastic flasks were placed in each of the two chambers, one for RF and one for sham exposure.
Sham exposure	A sham exposure was conducted.
Additional info	The air flow was on to cool the exposed cells, except for a series of experiments performed without air cooling at 6.0 W/kg. The computerised setup enabled performing experiments in a blinded manner.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	2.5 W/kg	-	-	-	-
SAR	6 W/kg	-	-	-	-

Measurement and calculation details

The description of dosimetry was published elsewhere [Nikoloski et al., 2005].

Exposure 2

Main characteristics

Frequency	835 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 2, 8, or 24 h

Modulation

Modulation type	pulsed
Duty cycle	33.3 %
Repetition frequency	50 Hz
Additional info	D-AMPS modulated signal

Exposure setup

Exposure source	same setup as exposure 1
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	2.5 W/kg	-	-	-	-
SAR	6 W/kg	-	-	-	-

Exposure 3

Main characteristics

Frequency	872 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 8 h

Modulation

Modulation type	pulsed
Duty cycle	33.3 %
Repetition frequency	50 Hz
Additional info	modulation similar to that used in the D-AMPS system

Exposure setup

Exposure source	waveguide
Chamber	The waveguide exposure system described previously [Hoyto et al., 2006] provided a uniform SAR distribution (±35%) in cell cultures, and a water cooling system enabled exposure in controlled temperature (±0.3°C).
Setup	Cells plated in two 55-mm glass Petri dishes were placed in each of the two chambers, one for RF and one for sham exposure.
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	6 W/kg	-	-	-	-

Reference articles

Höytö A et al. (2006): Modest increase in temperature affects ODC activity in L929 cells: Low-level radiofrequency radiation does not
Nikoloski N et al. (2005): Reevaluation and improved design of the TEM cell in vitro exposure unit for replication studies
Penafiel LM et al. (1997): Role of modulation on the effect of microwaves on ornithine decarboxylase activity in L929 cells

Exposed system:

intact cell/cell culture
murine L929 fibroblast cells

Methods Endpoint/measurement parameters/methodology

cell function: enzyme activity of ornithine decarboxylase (measurement of ¹⁴CO₂ release; scintillation counting)

Investigated system:

cell lysates

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The study did not confirm previous data reporting increased ornithine decarboxylase enzyme activity. When an exposure system was used similar to that of previous studies (Crawford cell), ornithine decarboxylase activity was either not affected (8 or 24 h exposures) or decreased (after a 2 h exposure at 6 W/kg). The decrease was statistically significant only for L929 cells purchased from ATCC cell bank and most pronounced when cooling with air flow was not used.
Different results were found in experiments with another exposure system with more efficient temperature control: ornithine decarboxylase activity was increased after 8 h of exposure at 6 W/kg when the temperatures of exposed cultures and control groups were kept identical (statistically significant for D-AMPS signal). Further studies are warranted to explore whether this finding reflect a true non-thermal effect.
The present study did not provide evidence for modulation-specific effects (no difference between CW- and D-AMPS signals in any of the experiments).

Study character:

Study funded by

Finnish Cultural Foundation of Northern Savo
GSM Association, UK/Ireland
Mobile Manufacturers Forum (MMF), Belgium
Tekes (National Technology Agency), Finland

Replicated studies

Litovitz TA et al. (1997): Bioeffects induced by exposure to microwaves are mitigated by superposition of ELF noise
Penafiel LM et al. (1997): Role of modulation on the effect of microwaves on ornithine decarboxylase activity in L929 cells

Ravera S et al. (2010): Sinusoidal ELF magnetic fields affect acetylcholinesterase activity in cerebellum synaptosomal membranes
Fortune JA et al. (2010): Radio frequency radiation causes no nonthermal damage in enzymes and living cells
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
Hoyto A et al. (2008): Radiofrequency radiation does not significantly affect ornithine decarboxylase activity, proliferation, or caspase-3 activity of fibroblasts in different physiological conditions
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. (2006): Modest increase in temperature affects ODC activity in L929 cells: Low-level radiofrequency radiation does not
Desta AB et al. (2003): Non-thermal exposure to radiofrequency energy from digital wireless phones does not affect ornithine decarboxylase activity in L929 cells
Litovitz TA et al. (1997): Bioeffects induced by exposure to microwaves are mitigated by superposition of ELF noise
Penafiel LM et al. (1997): Role of modulation on the effect of microwaves on ornithine decarboxylase activity in L929 cells
Litovitz TA et al. (1993): The role of coherence time in the effect of microwaves 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

Ornithine decarboxylase activity of L929 cells after exposure to continuous wave or 50 Hz modulated radiofrequency radiation--a replication study med./bio.

Aim of study (acc. to author)

Background/further details

Endpoint

Exposure

General information

Exposure 1

Main characteristics

Modulation

Exposure setup

Parameters

Measurement and calculation details

Exposure 2

Main characteristics

Modulation

Exposure setup

Parameters

Exposure 3

Main characteristics

Modulation

Exposure setup

Parameters

Reference articles

Methods Endpoint/measurement parameters/methodology

Main outcome of study (acc. to author)

Study funded by

Replicated studies

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