Authors

Zhijian C, Xiaoxue L, Yezhen L, Shijie C, Lifen J, Jianlin L, Deqiang L, Jiliang H. Impact of 1.8-GHz radiofrequency radiation (RFR) on DNA damage and repair induced by doxorubicin in human B-cell lymphoblastoid cells. Mutat Res.  Ahead of print. Oct 12, 2009.

Background
Evidence from numerous studies suggests that radiofrequency radiation (RFR) at non-thermal power densities does not directly induce DNA damage. Controversy still exists about the possibility of synergic effects between non-thermal radiofrequency radiation and chemical or physical mutagens. Doxorubicin (DOX) is an anthracycline antibiotic used for cancer treatment. Radiofrequency radiation from mobile phone may pose risk to individuals exposed to Doxorubicin.

Objective
The objective of this in vitro study was to investigate whether there are synergic effects of radiofrequency radiation and Doxorubicin.

Methods
The impact of 1.8 GHz radiofrequency radiation (SAR=2 W/kg, the ICNIRP safety limit)) on DNA damage and repair induced by Doxorubicin in human B-lymphoblastoid cells was examined using the alkaline comet assay. The temperature was kept at 37±0.1ºC and the difference between the radiofrequency radiation and sham-exposed cultures was not more than 0.1ºC. The cells were exposed or sham-exposed intermittently (field on for 5 minutes, field off for 10 minutes). Doxorubicin doses were 0, 0.05, 0.075, 0.10, 0.15, and 0.20 µg/ml; the exposure duration was 2 hours. Five types of combinations of the two exposures were tested. A comet assay was performed 0, 6, 12, 18, and 24 hours after Doxorubicin treatment. The percent of DNA in the tail (% tail DNA) served as an indicator of DNA damage.

Results
There was no significant difference in DNA damage between radiofrequency radiation exposed and sham-exposed cells (p>0.05). Exposure to Doxorubicin resulted in a significant increase in DNA damage at all the combinations of RFR/sham and Doxorubicin exposure, and a dose-response was observed for Doxorubicin exposure. A significant increase in DNA damage at 6 and 12 hours of repair time for Doxorubicin doses 0.075, 0.10, 0.15 and 0.20 µg/ml was observed only in the E-E-E exposure group (RFR pre-exposure for 2 hours, then simultaneous RFR-DOX exposure and then exposure to RFR for 6, 12, 18, and 24 hours after Doxorubicin exposure). Similar effects were observed only at individual time points and doses (0.075 µg/ml at 12 hours and 0.10 µg/ml at 6 hours) in E-S-S type of RFR exposure (pre-exposure to RFR for 2 hours and no RFR exposure during or after Doxorubicin exposure). No effect was observed in RFR exposure groups S-S-E or S-E-S.

Interpretation and Conclusion
No evidence was observed that 1.8 GHz RFR exposure at SAR of 2.0 W/kg induced DNA damage directly. Exposure to 1.8 GHz RFR at 2.0 W/kg may have some impact on repair of DNA damage induced by Doxorubicin.

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