Medical/biological study (experimental study)

Influence of 400, 900, and 1900 MHz electromagnetic fields on Lemna minor growth and peroxidase activity med./bio.

By: Tkalec M, Malaric K, Pevalek-Kozlina B

Published in: Bioelectromagnetics 2005; 26 (3): 185-193

Aim of study (acc. to author)

Duckweed Lemna minor was used as a model plant for investigating the effects of electromagnetic fields on growth and changes in peroxidase activity.

Background/further details

Peroxidases are widely distributed enzymes in plants where they play many important roles in growth, differentiation and development processes. Different environmental factors can change peroxidase activity so it is often used as a biomarker for plants exposed to stress.

Endpoint

plant growth and peroxidase activity

Exposure

- microwaves

Exposure	Parameters
Exposure 1: 400 MHz Modulation type: CW Exposure duration: continuous for 2, 4, and 14 h	electric field strength: 10 V/m unspecified (for 14 h) electric field strength: 23 V/m unspecified (for 2 h and 4 h) electric field strength: 41 V/m unspecified (for 2 h) electric field strength: 390 V/m unspecified (for 2 h)
Exposure 2: 400 MHz Modulation type: AM Exposure duration: continuous for 2 h	electric field strength: 23 V/m unspecified
Exposure 3: 900 MHz Modulation type: CW Exposure duration: continuous for 2, 4, and 14 h	electric field strength: 10 V/m unspecified (for 14 h) electric field strength: 23 V/m unspecified (for 2 h and 4 h) electric field strength: 41 V/m unspecified (for 2 h) electric field strength: 390 V/m unspecified (for 2 h)
Exposure 4: 900 MHz Modulation type: AM Exposure duration: continuous for 2 h	electric field strength: 23 V/m unspecified
Exposure 5: 1,900 MHz Modulation type: CW Exposure duration: continuous for 14 h	electric field strength: 10 V/m unspecified

General information

Plants were exposed to 400 and 900 MHz at different field strengths (23, 41, and 390 V/m) for 2 h and to 400, 900, and 1900 MHz at 10 V/m for 14 h. At a field strength of 23 V/m, the effect of longer exposure (4 h) and field modulation (80% AM 1 kHz sinusoidal) was also tested.

Exposure 1

Main characteristics

Frequency	400 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 2, 4, and 14 h
Additional info	Reference article: Malaric K, Sarolic A, Roje V, Bartolic J, Modlic B. 2001. Measured distribution of electric field in GTEM-cell. In: Proc. IEEE International Symposium on Electromagnetic Compatibility, Vol. 1., Montreal, Canada, August, 2001, pp 139-141.

Modulation

Modulation type	CW

Exposure setup

Exposure source	GTEM cell
Chamber	The GTEM cell was 0.6 m wide and 0.4 m high at the end, and 1.15 m long. The inner conductor was at 3/4 height with an angle septum/bottom plate of 15°, and septum/top plate of 5°.
Setup	Plants were kept in plastic Petri dishes (d = 9 cm, h = 1.5 cm) on the surface of a solid nutrient medium layer that was 0.2 cm thick. Five Petri dishes were arranged like the Olympic rings, in the same plane and on a dielectric support, perpendicular to the electric field, and placed below the septum for the three lower field strengths but on the septum for the highest field strength. In both cases, the area where plants were placed had the most uniform field distribution (± 0.1 dB).
Sham exposure	A sham exposure was conducted.
Additional info	For each experiment, control plants in field free environment were handled in the same way and kept in the same growth conditions as treated ones. In preliminary experiments, no significant differences between plants sham exposed in the GTEM cell and plants outside the GTEM cell were found. The temperature at the beginning and at the end of the measurements as well as between control and exposed plants varied no more than ± 0.1 °C.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
electric field strength	10 V/m	unspecified	measured and calculated	-	for 14 h
electric field strength	23 V/m	unspecified	measured and calculated	-	for 2 h and 4 h
electric field strength	41 V/m	unspecified	measured and calculated	-	for 2 h
electric field strength	390 V/m	unspecified	measured and calculated	-	for 2 h

Measurement and calculation details

Field levels were measured with an electric field probe, and results were verified with numerical methods (finite element method) [Malaric et al., 2001].

Exposure 2

Main characteristics

Frequency	400 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 2 h

Modulation

Modulation type	AM
Modulation frequency	1 kHz
Modulation depth	80 %
Additional info	sinusoidal

Exposure setup

Exposure source	same setup as exposure 1

Parameters

Measurand	Value	Type	Method	Mass	Remarks
electric field strength	23 V/m	unspecified	measured and calculated	-	-

Exposure 3

Main characteristics

Frequency	900 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 2, 4, and 14 h

Modulation

Modulation type	CW

Exposure setup

Exposure source	same setup as exposure 1

Parameters

Measurand	Value	Type	Method	Mass	Remarks
electric field strength	10 V/m	unspecified	measured and calculated	-	for 14 h
electric field strength	23 V/m	unspecified	measured and calculated	-	for 2 h and 4 h
electric field strength	41 V/m	unspecified	measured and calculated	-	for 2 h
electric field strength	390 V/m	unspecified	measured and calculated	-	for 2 h

Exposure 4

Main characteristics

Frequency	900 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 2 h

Modulation

Modulation type	AM
Modulation frequency	1 kHz
Modulation depth	80 %
Additional info	sinusoidal

Exposure setup

Exposure source	same setup as exposure 1

Parameters

Measurand	Value	Type	Method	Mass	Remarks
electric field strength	23 V/m	unspecified	measured and calculated	-	-

Exposure 5

Main characteristics

Frequency	1,900 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 14 h

Modulation

Modulation type	CW

Exposure setup

Exposure source	same setup as exposure 1

Parameters

Measurand	Value	Type	Method	Mass	Remarks
electric field strength	10 V/m	unspecified	measured and calculated	-	-

Exposed system:

plant
Lemna minor L. (duckweed)
whole body

Methods Endpoint/measurement parameters/methodology

plant growth; peroxidase activity (spectrophotometry)

Investigated system:

plant extracts
investigation on living organism

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The growth of plants exposed to the 23 V/m electric field of 900 MHz for 2 h significantly decreased in comparison with the control. An electric field of the same electric field strength but at 400 MHz did not have such effect. A modulated field at 900 MHz inhibited the growth, while at 400 MHz modulation did not influence the growth significantly. At both frequencies a longer irradiation mostly decreased the growth and the highest electric field (390 V/m) strongly inhibited the growth. Irradiation of plants to lower field strength (10 V/m) for 14 h caused significant decrease at 400 and 1900 MHz, while 900 MHz did not influence the growth.
Peroxidase activity in irradiated plants varied, depending on the exposure characteristics. Revealed alterations were mostly small, except in plants exposed for 2 h to 41 V/m at 900 MHz where a significant increase was found.
The data suggest that investigated electromagnetic fields might influence plant growth and, to some extent, peroxidase activity. However, the effects strongly depended on the field characteristics.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Ministry of Science and Technology (later on "Ministry of Science, Education and Sport"), Croatia

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Influence of 400, 900, and 1900 MHz electromagnetic fields on Lemna minor growth and peroxidase activity 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

Exposure 4

Main characteristics

Modulation

Exposure setup

Parameters

Exposure 5

Main characteristics

Modulation

Exposure setup

Parameters

Methods Endpoint/measurement parameters/methodology

Main outcome of study (acc. to author)

Study funded by

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