A study on biological effects of low-intensity millimeter waves

Resonance-like biological effects of millimeter-wave radiation at frequencies of approximately 42 GHz on the growth rate of E. coli and on DNA have been reported in several scientific publications. In order to explore these nonthermal effects, we have measured the growth rate and the absorption spectrum of E. coli, irradiated by millimeter waves in the frequency range from 41 to 43 GHz. In addition, the effect of this radiation on DNA was studied by measuring plasmid transformation efficiency. Both the growth rate variations with varying frequency and the variations in the result of the plasmid transformation efficiency experiments were found to be statistically insignificant. Resonance-like absorption features observed in the absorption spectrum of E. coli were identified as modes generated in the millimeter-wave system, when the sample was inserted. The experimental results indicate that resonance effects are unlikely in this particular frequency range.