What follows is the continuation, in serial form, of a central chapter from my book A Primer in the Art of Deception: The Cult of Nuclearists, Uranium Weapons and Fraudulent Science.
SCAM NUMBER TWENTY-SIX: Underestimate the risk of damage to cells from low-level radiation by making the false comparison between normal free radical damage and damage caused by ionizing radiation.
Routinely, an enormous number of free radicals are produced in cells, and these induce molecular damage to DNA and other important cellular structures. Exposure to ionizing radiation creates a much smaller number of additional free radicals. Based on these facts, those who deny the hazard of low-dose radiation make the argument that since cellular mechanisms routinely repair naturally occurring free radical damage, they obviously have the capacity to repair damage induced by ionizing radiation. This is a seductive and seemingly convincing argument. However, as John Gofman points out, it is based on two false assumptions: “(1) that the nature of damage done by ionizing radiation is the same as the nature of damage done by routine metabolic free radicals, and (2) that damage therefore can be compared by comparing the relative numbers of free radicals” .
Gofman demolishes these two assumptions in his article, “The Free-Radical Fallacy about Ionizing Radiation: Demonstration that a Popular Claim is Senseless”. His argument runs as follows: By some estimates, the DNA of each cell in the body is exposed to between 120,000 and 240,000 damage events per day from intrinsic metabolic processes. In response, cellular mechanisms are rapidly activated that repair this damage. If the damage caused by radiation is not qualitatively different from normal free radical damage, which is the basic assumption of the Free-Radical Fallacy, then repair mechanisms should have the capacity of undoing an equivalent amount of damage produced by ionizing radiation. Can this be the case? Gofman’s response is as follows. Understanding exists as to the repair capacity of the human organism. Estimates exist for the number of damaging events produced in each cell by each rad of absorbed dose. Further, experiments have confirmed that, in response to whole-body radiation of 100 rads delivered all at once, human cells mobilize a sufficient amount of repair enzymes to repair all genetic damage. In fact, repair capacity is not overwhelmed by the number of damaging events induced by 500 rads. Thus, the body has the capacity for perfect repair. However, a dose of many hundreds of rads is a lethal dose. Thus, perfect repair is not the central issue in the body’s ability to withstand radiation injury. From this simple thought experiment, Gofman arrives at the conclusion that either the nature of the damage caused by ionizing radiation or the nature of the repair process cannot possibly be the same for the oxidative damage of normal cellular processes and that caused by ionizing radiation. Gofman continues with the argument that repair capacity is not the issue, but that radiation damages cellular structures in complex ways that resist perfect repair. [Double-strand breaks to DNA are an example of complex damage compared to the more usual single-strand breaks caused by normal free radical damage.] Gofman states:
"The difference between free-radical damage from routine metabolism and from ionizing radiation almost surely lies in repairability. If DNA damage is perfectly repaired by a cell, such damage has no health consequences. It is inconsequential. The consequences arise only from injuries which are non-repairable or mis-repaired.
The power of ionizing radiation to induce particularly complex and unrepairable genetic injuries is surely related to a unique property of this agent. Ionizing radiation instantly unloads biologically abnormal amounts of energy at random in an irradiated cell. Biochemical reactions in a cell generally involve net energy-transfers in the ballpark of 10 electron-volts and below. By contrast, Ward reports that the average energy-deposit from low-LET ionizing radiation is thought to be about 60 electron-volts, all within an area having a diameter of only 4 nanometers. (The diameter of the DNA double-helix is 2 nanometers). In other words, ionizing radiation produces violent energy-transfers of a type simply absent in a cell's natural biochemistry.
Because of its unique property, ionizing radiation is a unique menace to our DNA and chromosomes. This fact needs wide recognition, as mankind learns that far more health problems are mutation-based than anyone could prove 15 years ago."
 Gofman J.W. The Free-Radical Fallacy about Ionizing Radiation: Demonstration that a Popular Claim is Senseless. September 1997. http://www.ratical.com/radiation/CNR/FreeRadFallacy.html