Study type: Medical/biological study (experimental study)

Low-intensity microwave irradiation does not substantially alter gene expression in late larval and adult Caenorhabditis elegans. med./bio.

Published in: Bioelectromagnetics 2009; 30 (8): 602-612

Aim of study (acc. to author)

To study the effects of low-intensity microwave irradiation on gene expression in the nematode Caenorhabditis elegans using a microwave exposure system that minimises temperature differences between sham exposed and exposed conditions (< / = 0.1°C).

Background/further details

In a previous study (de Pomerai et al. 2000), the authors suggested that low-intensity microwave fields could induce a non-thermal heat-shock response in the nematode Caenorhabditis elegans. This effect has been reinterpreted as a subtle thermal artefact caused by small temperature disparities (<0.2 °C) between exposed and sham exposed conditions (Dawe et al. 2006).
Larval stage L4 and adult worms were exposed. Positive controls were performed with mild heat shock (30°C). Five microarrays of pooled triplicate RNA populations from sham exposed and exposed worms, respectively, were compared.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1 GHz
Modulation type: CW
Exposure duration: continuous for 1.5 h ,2.5 h or 6 h
  • power: 0.5 W
  • SAR: 0.9 mW/kg minimum
  • SAR: 3 mW/kg maximum

Exposure 1

Main characteristics
Frequency 1 GHz
Type
Exposure duration continuous for 1.5 h ,2.5 h or 6 h
Modulation
Modulation type CW
Exposure setup
Exposure source
Setup silver-plated TEM cell for exposure; copper TEM cell for sham exposure
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power 0.5 W - - - -
SAR 0.9 mW/kg minimum measured and calculated - -
SAR 3 mW/kg maximum measured and calculated - -

Reference articles

  • Dawe AS et al. (2006): A small temperature rise may contribute towards the apparent induction by microwaves of heat-shock gene expression in the nematode Caenorhabditis Elegans.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

No genes showed consistent expression changes across all five microarray comparisons, and all expression changes appeared modest after normalisation (< / = 40% up-regulated or down-regulated). The number of statistically significant differences in gene expression (846) was less than the false-positive rate expected by chance (1131).
The authors conclude that the pattern of gene expression in L4/adult Caenorhabditis elegans is unaffected by low-intensity microwave exposure; the minor changes found could well be false positives.

Study character:

Study funded by

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