In a recent ANS Nuclear Cafe post, I mentioned the radiation hormeis theory proposed more than three decades ago by Dr. Don Luckey, a biochemist and nutritionist who wrote a book in 1980 titled Hormesis With Ionizing Radiation. According to Dr. Luckey and a number of other researchers in the field, a small dose of radiation can provide beneficial effects.
As a former nuclear power plant operator, it was once a little difficult for me to accept that notion. After all, I had been taught – repeatedly – to keep radiation doses As Low As Reasonably Achievable. Early in my nuclear career, I was involved in planning work that resulted in a great deal of additional expenditures and manpower in order to reduce doses by a fraction of the amount that Dr. Luckey has said will not cause harm and may actually do some good.
About 15 years ago, I had the pleasure of meeting people like Jim Muckerheide, Jerry Cuttler and Ted Rockwell who introduced me to the study of the health effects of low level radiation and opened my eyes to the massive amount of peer reviewed and published information that is not widely shared or promoted. They have also helped me to find many unpublished studies – like the famous nuclear shipyard workers study that was completed but never released by the Department of Energy.
A few days ago, I asked Dr. Cuttler to help me explain just how the beneficial effects of radiation work. Here is his boiled down explanation – which I will follow with some links to far more detailed studies.
As Myron Pollycove and Ludwig Feinendegen have been explaining in their papers over the past ten years (also in my article Nuclear Energy and Health), there is a tremendous rate of endogenous DNA damage occurring in all organisms due to normal energy production, i.e., oxydation of glucose. Reactive oxygen species (ROS) attack the DNA continuously as we breathe, but each organism has powerful defences that prevent (via antioxidant production), repair and remove DNA damage. The net result is an average of one permanent mutation per cell per day.
The contribution of normal background ionizing radiation to this DNA damage rate is about ten million times less than the endogenous DNA damage rate. The effect of a small increase in the background radiation level is to produce a small increase in the DNA damage rate. This produces a low level of stress on the activity of the defences (damage-control biosystem), which stimulates this system to work harder, i.e., perform much better (producing a reduction in the DNA mutation rate). A large increase in radiation level inhibits this system (resulting in an increase in the DNA mutation rate). Harmful effects begin to surpass beneficial effects for an acute dose above 50 rad (0.5 Gy).
To summarize, the major effect of radiation on organisms (i.e., humans) is its effect on the damage-control biosystem, not its direct damage to the DNA molecules. This increase in the amount of DNA damage is relatively trivial—orders of magnitude less than the decrease in the amount of DNA damage due to the stimulation of defences (radiation hormesis).
Based upon human data, a single whole-body dose of 150 mSv (15 rem) is safe. The high natural radiation level of 700 mSv per year (70 rem/year), corresponding to a 70-year lifetime dose of 49 Sv in Ramsar, Iran, is also safe. Both these single and continuous doses are also beneficial (Cuttler and Pollycove 2009). This conclusion is applicable to humans of all ages and to sensitive, cancer-prone individuals.
Observations on the Chernobyl Disaster and LNT, Zbigniew Jaworowski, Dose-Response. 2010
NCRP Report No. 136 – How to ignore data that contradict the LNT hypothesis, Dr. John Cameron, Radiation Science and Health, June 14, 2006