FREE RADICALS AS A POSSIBLE CAUSE OF 

 MUTATIONS AND CANCER* 



Walter Gordy 



Department of Physics, Duke University, 

 Durham, North Carolina 



Abstract — The hypothesis set forth in this note is that free radicals produced outside the body 

 may find their way into the body and produce mutations and/or cancer. The evidence for 

 support of this hypothesis is the presence of radicals as detected by microwave paramagnetic 

 resonance in several carcinogenic agents, and the fact that free radicals are now recognized 

 by radiobiologists as being responsible for a large portion of mutagenic and carcinogenic 

 effects of ionizing radiations. 



Free radicals may be loosely defined as molecular fragments which are charac- 

 terized by a free valence or an unpaired electron. Because of their highly 

 reactive nature they are not thought to exist in any significant quantity within 

 the organic matter about us, although they are often postulated as important, 

 transient intermediaries in organic and biochemical reactions. Within the 

 past few years, however, microwave spectroscopists (I) have shown that free 

 radicals can be readily detected in organic matter which has been subjected 

 to some form of pre-treatment that can break chemical bonds. Such free 

 radicals are produced in the combustion of organic matter — wood, paper, 

 tobacco, coal, oil. They are produced in excessively cooked foods such as 

 charred steak or scorched toast. They are produced in various forms of matter 

 by ultraviolet light, by x-rays, or by atomic radiation. 



The radicals are detected through their resonant absorption of microwave 

 or radio-wave energy when they are placed in a magnetic field of the proper 

 strength. This type of absorption spectrum is known as paramagnetic resonance 

 or as electron spin resonance (2). Electrons in normal chemical bonds are 

 paired in such a manner that their spins and magnetic moments cancel, and 

 hence they exhibit no paramagnetic absorption. Paramagnetic resonance 

 occurs only for the unpaired electrons of the disrupted chemical bond. It 

 therefore provides a specific and powerful means of detecting and studying 

 reactive free radicals within organic matter without interfering absorption or 

 confusing signals from the normal stable molecules of the matter. 



The surprising new evidence from paramagnetic resonance is not that free 

 radicals can be easily produced but that they become trapped and stabiUzed 

 and can be transported from place to place, even through the air within tiny 

 particles of soUd matter such as those in smoke. The nature of neither the 

 radicals nor their cages is yet known definitely, although some radicals produced 



* This research was supported by the United States Air Force through the Air Force Office 

 of Scientific Research of the Air Research and Development Command under contract 

 No. AF18(600)-497. Reproduction in whole or in part is permitted for any purpose of the 

 United States Government. 



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