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Medical/biological study (experimental study)

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

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

Exposure

Exposure Parameters
Exposure 1: 400 MHz
Modulation type: CW
Exposure duration: continuous for 2, 4, and 14 h
Exposure 2: 400 MHz
Modulation type: AM
Exposure duration: continuous for 2 h
Exposure 3: 900 MHz
Modulation type: CW
Exposure duration: continuous for 2, 4, and 14 h
Exposure 4: 900 MHz
Modulation type: AM
Exposure duration: continuous for 2 h
Exposure 5: 1,900 MHz
Modulation type: CW
Exposure duration: continuous for 14 h
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
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
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
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
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
Charakteristic
  • guided field
Exposure duration continuous for 2, 4, and 14 h
Modulation
Modulation type CW
Exposure setup
Exposure source
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
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
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
Charakteristic
  • guided field
Exposure duration continuous for 14 h
Modulation
Modulation type CW
Exposure setup
Exposure source
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

Investigated material:
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:

Study funded by

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

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