Sannino, A.; Sarti, M.; Reddy, S. B.; Prihoda, T. J.; Vijayalaxmi, and Scarfi, M. R. Induction of adaptive response in human blood lymphocytes exposed to radiofrequency radiation. Radiat Res. 2009 Jun; 171(6):735-42.
The n phenomenon of an adaptive response, when cells exposed to a very small adaptation dose of a genotoxic agent become less susceptible to genetic damage from a higher (challenge) dose of the same or similar agent, has been observed in vitro and in vivo. This phenomenon has been extensively studied using ionizing radiation.
The aim of this study was to investigate whether an adaptation dose of non-ionizing RF radiation (a non-genotoxic agent) makes cells less susceptible to genetic damage caused by a subsequent challenge dose of a known genotoxic agent mitomycin C.
Peripheral blood lymphocytes from five healthy human volunteers were used in this experiment. The cells were exposed to an adaptation dose of 900 MHz RF radiation for 20 hours at an average SAR of 1.25 W/kg corresponding to 10 W/kg peak value. The challenge dose 100 ng/ml of mitomycin C was added to RF-radiation and sham-exposed cells at 48 hours after the cell culture initiation. The induction of an adaptive response was assessed by using the cytokinesis-block micronucleus (MN) assay.
Cells from four donors exhibited an adaptive response: pre-exposure to RF radiation resulted in a significant decrease in the frequency of MN induced by the challenge dose of mitomycin C compared to the sham-exposed cells challenged with mitomycin C. No adaptive response was observed in one donor.
Interpretation and conclusion
The study has shown that exposure to a non-genotoxic agent, RF radiation at a frequency used for wireless communications, can induce an adaptive response in human blood lymphocytes. The findings (presence of an adaptive response in four individuals and its absence in one) also indicate the existence of inter-individual variability in this respect. Further studies are required to find out whether an adaptive response can be induced in other in vitro and in vivo experimental conditions, such as different cell types, radiation frequencies, SARs, timing of adaptive and challenge dose.