INTRINSIC MUTATIONS

"The Health Effects of Low-Level Radiation'' by Myron Polly-cove, Health & Environment Digest 10, No. 7, pp 52 -54, November (1996), available from the Freshwater Foundation, 2500 Shadywood Road, Excelsior, MN 55331, is an excellent summary of some of the best experiments showing that ionizing radiation, in low to moderate doses, increases human health. These have been described in previous issues of Access to Energy except for "Mortality from Breast Cancer after Irradiation during Fluoroscopic Examination in Patients Being Treated for Tuberculosis, A. B. Miller, et al, New England Journal of Medicine 321, pp 1285-1289 (1989). In this study, breast cancer deaths decreased by 40% in women who received about 0.15 Gy of radiation. At about 0.35 Gy, the death rate was the same as for women who were not irradiated. Above 0.35 Gy, the death rate gradually increased to a level of about twice the nonirradiated group at 1.75 Gy.

Pollycove summarizes the molecular biological discoveries (appropriate literature references are in his article) that permit us to understand why radiation improves health as follows:

1. "The very high background of intrinsic potential mutations (240,000/cell/day) produced by reactive oxygen metabolytes (ROM: free radicals and H 2O2) and thermal instability compared to 20 potential mutations produced predominately by the free radicals generated by 1 r of low linear energy transfer (LET) radiation. By comparison, the average background radiation in the U.S., including radon, is approximately one-third r. In addition, by fundamental limitations on the accuracy of DNA replication and repair, every single gene is likely to undergo 400,000 unrepaired mutations per day in each person.''

2. "The presence of an active DNA damage control biosystem that, until declining with age, effectively prevents, repairs and removes intrinsic and environmental mutations.''

3. "The activity of the DNA damage control biosystem is decreased by high dose (e.g., at or above 100r), high-dose-rate (at or above 20r per m) radiation, but adaptively responds with increased activity to low dose (e.g., at or below 20r), low-dose-rate (e.g., at or below 1r per m) radiation as well as low-dose toxic chemical agents.''

In other words, the ordinary chemical deterioration and rebuilding of cellular genetic material in living things is so great in magnitude that deterioration from low doses of radiation does not contribute significantly to the destruction and replacement that is an essential function of life. Low doses of radiation and toxic chemicals do, however, stimulate the ordinary repair mechanisms to work harder. The net result is that these repair systems do a better job of correcting ordinary natural biochemical deterioration, so health is better rather than poorer as a result of low exposures to radiation and toxic chemicals.