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Medical/biological study (experimental study)

Exposure to radiofrequency radiation induces oxidative stress in duckweed Lemna minor L.

Published in: Sci Total Environ 2007; 388 (1-3): 78-89

Aim of study (acc. to author)

To study the physiological responses of the duckweed after exposure to radiofrequency electromagnetic fields, and in particular, to clarify the possible role of oxidative stress.
Background/further details: Cadmium and heat (42°C, 2h) were used for positive controls.

Endpoint

Exposure

    • RF field
Exposure Parameters
Exposure 1: 400–900 MHz
Modulation type: CW
Exposure duration: continuous for 2 h
Exposure 2: 400–900 MHz
Modulation type: CW
Exposure duration: continuous for 2 hr or 4 hr
Exposure 1
Main characteristics
Frequency 400–900 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2 h
Additional info 400 and 900 MHz were used
Modulation
Modulation type CW
Exposure setup
Exposure source
  • GTEM cell
  • [Tkalec et al., 2005 and Malaric et al., 2005]
Setup Five plastic Petri dishes were placed in the GTEM cell in the same plane but perpendicular to the field. The area where plants were placed had the most uniform field distribution (±0.1 dB) as tested with an electric probe.
Sham exposure A sham exposure was conducted.
Additional info The temperature inside the GTEM cell and on the plant surface did not vary by more than ±0.1 °C.
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 10 V/m - measured - -
power density density 0.3 W/m² - - - -
electric field strength 23 V/m - measured - -
power density density 1.4 W/m² - - - -
electric field strength 41 V/m - measured - -
power density density 4.2 W/m² - - - -
electric field strength 120 V/m - measured - -
power density density 38.2 W/m² - - - -
Exposure 2
Main characteristics
Frequency 400–900 MHz
Type
Charakteristic
  • guided field
Exposure duration continuous for 2 hr or 4 hr
Additional info 400 and 900 MHz were used
Modulation
Modulation type CW
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 23 V/m - measured - -
power density density 1.4 W/m² - - - -
Reference articles
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)

At 400 MHz, lipid peroxidation and hydrogen peroxide content were significantly enhanced in duckweed exposed to electromagnetic fields of 23 and 120 V/m, while other exposures did not have an effect.
Compared to the controls, catalase enzyme activity increased after most exposure treatments while pyrogallol and ascorbate peroxidase enzyme activities were not changed. Exceptions were reduced pyrogallol and ascorbate peroxidase enzyme activity after longer exposure at 23 V/m and increased pyrogallol enzyme activity after exposures at 10 and 120 V/m.
By contrast, at 900 MHz almost all exposure treatments significantly increased lipid peroxidation and hydrogen peroxide content but mostly decreased pyrogallol enzyme activity and did not affect catalase enzyme activity. Exceptions were exposures to a modulated electromagnetic field and to the electromagnetic field of 120 V/m which increased pyrogallol and catalase enzyme activity. At this frequency ascorbate peroxidase activity was significantly decreased after exposure at 10 V/m and longer exposure at 23 V/m but it increased after a shorter exposure at 23 V/m.
At both frequencies no differences in isoenzyme patterns of antioxidative enzymes or HSP70 level were found between control and exposed plants.
The data showed that non-thermal exposure under these experimental conditions induced oxidative stress in duckweed as well as unspecific stress responses, especially of antioxidative enzymes. However, the effects markedly depended on the electromagnetic field frequencies applied as well as on other exposure parameters (field strength, modulation and exposure time).
Study character:

Study funded by

  • Ministry of Science, Education and Sports, Republic of Croatia

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