Role of modulation on the effect of microwaves on ornithine decarboxylase activity in L929 cells

Bioelectromagnetics. 1997;18(2):132-41. doi: 10.1002/(sici)1521-186x(1997)18:2<132::aid-bem6>;2-3.


The effect of 835 MHz microwaves on the activity of ornithine decarboxylase (ODC) in L929 murine cell was investigated at an SAR of approximately 2.5 W/kg. The results depended upon the type of modulation employed. AM frequencies of 16 Hz and 60 Hz produced a transient increase in ODC activity that reached a peak at 8 h of exposure and returned to control levels after 24 h of exposure. In this case, ODC was increased by a maximum of 90% relative to control levels. A 40% increase in ODC activity was also observed after 8 h of exposure with a typical signal from a TDMA digital cellular telephone operating in the middle of its transmission frequency range (approximately 840 MHz). This signal was burst modulated at 50 Hz, with approximately 30% duty cycle. By contrast, 8 h exposure with 835 MHz microwaves amplitude modulated with speech produced no significant change in ODC activity. Further investigations, with 8 h of exposure to AM microwaves, as a function of modulation frequency, revealed that the response is frequency dependent, decreasing sharply at 6 Hz an 600 Hz. Exposure with 835 MHz microwaves, frequency modulated with a 60 Hz sinusoid, yielded no significant enhancement in ODC activity for exposure times ranging between 2 and 24 h. Similarly, exposure with a typical signal from an AMPS analog cellular telephone, which uses a form of frequency modulation, produced no significant enhancement in ODC activity. Exposure with 835 MHz continuous wave microwaves produced no effects for exposure times between 2 and 24 h, except for a small but statistically significant enhancement in ODC activity after 6 h of exposure. Comparison of these results suggests that effects are much more robust when the modulation causes low-frequency periodic changes in the amplitude of the microwave carrier.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Cell Line
  • Diffusion Chambers, Culture
  • Electromagnetic Fields / adverse effects
  • Environmental Exposure / adverse effects
  • Enzyme Activation / radiation effects
  • Fibroblasts / enzymology
  • Fibroblasts / metabolism
  • Fibroblasts / radiation effects
  • Mice
  • Microwaves / adverse effects*
  • Ornithine Decarboxylase / chemistry
  • Ornithine Decarboxylase / metabolism*
  • Ornithine Decarboxylase / radiation effects*
  • Radio Waves / adverse effects
  • Signal Transduction / radiation effects
  • Telephone


  • Ornithine Decarboxylase