Medical/biological Study (experimental study)

Induction of an adaptive response in human blood lymphocytes exposed to radiofrequency fields: Influence of the universal mobile telecommunication system (UMTS) signal and the specific absorption rate. med./biol.

PubMed Entry

Journal web site

Aim of study (according to author)
To examine the influence of different specific absorption rates on the adaptive response induced by the exposure of human blood lymphocytes to radiofrequency fields.
Background/further details:
Former studies have shown that different cell types exposed to an extremely small adaptation dose of a genotoxic agent are less susceptible to the induction of a genetic damage when given a higher challenge dose of the same or a similar genotoxic agent. The induction of an adaptive response was shown to be influenced by several factors (e.g. the dose used for adaptation, the dose rate, the time between the adaptation and challenge doses).
Blood lymphocytes of nine male healthy donors were stimulated for 24 h with phytohaemagglutinin and then exposed for 20 hours to an adaptive dose of 1950 MHz radiofrequency field at different specific absorption rates (1.25, 0.6,0.3 and 0.15 W/kg). This was followed by a challenge dose of 100 ng/ml mitomycin C. Cells were collected after 72 h total culture period and the frequency of micronuclei was recorded.
The lymphocytes from donors 1-3 were exposed at 1.25 and 0.3 W/kg while the lymphocytes from donors 4-6 were exposed at 0.6 and 0.15 W/kg. Whole blood samples from donors 7-9 were employed to set up cultures exposed at 1.25 and 0.3 W/kg on day 1, and at 0.6 and 0.15 W/kg on day 2.

Endpoint

• genotoxicity/mutation: micronucleus formation

Exposure
General category: mobile communication system, digital mobile phone, UMTS, W-CDMA

Field characteristics	Parameters
1950 MHz exposure duration: continuous for 20 h	SAR: 0.3 W/kg (in the outer dishes in experiment 1) SAR: 1.25 W/kg (in the inner dishes in experiment 1) SAR: 0.15 W/kg (in the outer dishes in experiment 2) SAR: 0.6 W/kg (in the inner dishes in experiment 2)

Exposed system:
intact cell/cell culture (in vitro)

Methods
Endpoint/Measurement parameters/Methodology

• genotoxicity/mutation: micronucleus formation (cytokinesis block micronucleus assay; Giemsa stain; light microscopy)
• cell viability/cell division/proliferation: cytotoxicity (proliferation index (M1+2M2+3(M3+M4)/total number of cells; M1 to M4: number of cells with 1 to 4 nuclei); binucleate cell index (percentage of binucleated cells))

Main outcome of study (according to author)
In cell cultures of all nine donors, the frequencies of micronuclei in the lymphocytes exposed or sham exposed alone were not significantly different from those in untreated controls, while treatment of the cells with mitomycin C alone resulted in a significant increase compared with the untreated controls.
The results were different in different donors. According to the results between "radiofrequency field + mitomycin treatment" and the corresponding "sham exposure + mitomycin treatment", there were significant differences (decreases) at both 0.3 W/kg and 0.6 W/kg specific absorption rates. The data indicated that a radiofrequency field at 0.3 W/kg was a more reliable specific absorption rate to induce an adaptive response than a radiofrequency field at 0.6 W/kg.
Two donors did not show an adaptive response to mitomycin C nor to the radiofrequency field exposure.
The proliferation index in all cell cultures was not significantly different between untreated control lymphocytes, those exposed to "radiofrequency + mitomycin C", and those treated with mitomycin C alone.

(Study character: medical/biological study, experimental study, full/main study)

Study funded by

• not stated/none

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