One of the privileges of being a long time pronuclear activist on the Internet – an activity that I have been enjoying since “atomicrod” started posting in USENET discussion groups in the early 1990s – is that I often see communications between talented, highly qualified professionals that include information that is not well distributed in public.
The information is not secret, but sometimes people who really understand a technical topic are not predisposed to promote their knowledge outside of a small circle of colleagues. When they choose to publish, it is often in densely worded papers that show up in journals that are only available in good university libraries.
Recently, two of my internet colleagues shared some thoughts on the health effects of radiation. With permission, I decided to share them with you.
In the conversation below, Dr. George Stanford is a sodium cooled fast reactor specialist who earned his PhD in experimental nuclear physics from Yale University and then spent his career at Argonne National Laboratory. Dr. Jerry Cuttler earned his DSc in Nuclear Sciences in 1971 from the Technion, Israel Institute of Technology. He has spent the past 15+ years studying the health effects of low and moderate level radiation.
Dr. Stanford: You’re right, of course, about the benefits of low-level radiation. However, point (2) was in the context of a massive, near-lethal dose. Am I not correct in thinking that there is a small chance that a survivor might develop cancer later as a result? I have a male friend now in his 80s who as a teenager was given a truly outrageous, very extensive series of radiation doses to treat acne, and he developed breast cancer 5 or 10 years ago. I know that one case proves nothing, but perhaps one can legitimately wonder.
(On the other hand, I have another acquaintance who received a one-time dose of ~190 rem [1.9 Sv] in the late 1950s, and when I saw him a year or two ago, he was a very healthy 90-year-old.)
Dr. Cuttler: Hi George
Almost all DNA alterations are spontaneous/endogenous. Potential ones are mostly prevented by anti-oxidants and other defences. DNA alterations are mostly repaired by defences. Nearly all cells with DNA alterations that were not repaired commit suicide or are killed by various defences. Mutated cells that eventually develop into cancer cells are mostly killed by the immune system.
Radiation’s principal effect is on the defences. Low radiation doses/levels stimulate all the defences reducing the incidence of cancer. High doses/levels have the opposite effect.
While radiation alters DNA, this effect is usually small compared to the spontaneous rate of DNA alterations. Let’s consider whether “there is a small chance” that a cancer may develop due to DNA altered by a near-lethal dose of radiation.
Wade Allison points out that radiation treatments of tumours and post-surgical follow-up radiation treatments irradiate large amounts of healthy tissue (organs too) at 200 rad each day for 4 weeks. That amounts to 200 x 5 x 4 = 4000 rad in a month. There are many cells in this healthy tissue (10^9 per gram), and Allison says that these tissues recover. These irradiated areas do not become cancer ridden.
(Note: Dr. Cuttler is Canadian. His version of the English language includes slightly different ways to spell words like defenses and tumors.)
Dr. Stanford: Thanks, Jerry.
But this is the first time I have seen the assertion that there is never a long-term consequence from a near-lethal dose — if that’s what you’re saying. I would think it would be hard to substantiate, since people who need radiation treatments tend to be on in years, and probably die of something else before any induced cancer would have a chance to develop.
In any event, I suspect that, in trying to inform people about the (lack of) consequences of Fukushima, a claim that there is no such thing as a harmful, survivable dose would cause the message to be tuned out completely.
Dr. Cuttler: Hi George,
I tried to be clear, but perhaps I wasn’t. So I’ll try again. I did not say that “there is never a long-term consequence from a near lethal dose.”
The remark, “However, point (2) was in the context of a massive, near-lethal dose. Am I not correct in thinking that there is a small chance that a survivor might develop cancer later as a result?” links ionizing radiation to an increased risk of cancer. This is what Hermann Muller tried to do with his fruit fly studies and what he said in his Nobel Prize speech. This is what all the anti-nuclear folks do. They associate nuclear radiation with cancer, and then campaign to shut down nuclear energy plants and block construction of new plants.
I tried to point out that radiation has an indirect effect on cancer incidence. The cancer starts with the very high rate of DNA alteration, which is almost totally spontaneous/endogenous (see attached paper). Average, healthy people have very powerful defences that: 1) prevent DNA damage, 2) repair DNA damage and 3) remove damaged or mutated cells, including cancer cells. Cancer disease develops when our defences fail to prevent it. The figure below shows that the effectiveness of our defences weakens with increasing age.
Whole-body radiation’s principal effect is on our defences; radiation modulates the activities of our defences. Low radiation doses/levels stimulate all the defences reducing the incidence of cancer. High doses/levels have the opposite effect.
Wade Allison is an expert on medical radiation physics. His 2009 book “Radiation and Reason” has very important factual information on “A Single Dose of Radiation” (Chapter 6) and “Multiple Doses of Radiation” (Chapter 7). In the discussion on cancer radiation therapy, he points out that the standard treatment also irradiates healthy tissue that surrounds cancerous tumours. This tissue receives many near-lethal acute dose fractions, e.g., breast cancer: 16 fractions of 2.7 Gy (42.5 Gy); prostate cancer: 39 fractions of 2 Gy (78 Gy). Each fraction is delivered 5 times per week. The gap of one day allows repair and healing of healthy tissue to occur between each dose fraction.
The irradiated healthy tissue recovers its function, but there is some permanent damaged in the form of scarring. In a study of 20,871 breast cancer patients, there was a significant increase in the incidence of death from cardiac disease, after 15 or more years, in women who received radiotherapy to the left breast, compared with those who received it to the right breast.
“Radiation doses used in radiotherapy are high, and it is to be expected that, in addition to treating the cancer concerned, the radiation itself should occasionally initiate new disease. In principle, sufficient data are available to measure this, because the number of treated patients is very large. However, confounding effects make such studies difficult.” While it could be argued that this radiation damage could lead eventually to cancer, there is no solid evidence that this actually happens. This is why I stated below that these irradiated areas do not become cancer ridden.
So I come back to what Myron Pollycove explained to me: “Radiation acts on our defences,” which prevent cancer.
If a massive, near-lethal dose is delivered to the whole body, we are discussing acute radiation syndrome, not cancer. If you consider the 134 Chernobyl firefighters who were hospitalized for ARS, 28 died within months and 106 recovered. During the subsequent ~20 years, approximately 20 of these 106 people died. Jaworowski pointed out that this is in line with the normal incidence of mortality of these workers, about 1% per year. The causes of death were due mostly to lifestyle illnesses. There were one or two cancer cases, but it is possible they could have been caused by factors other than the radiation exposure 20 years ago.
To summarize, there is an enormous amount of data from cancer patients who received radiotherapy. There are long-term consequences—scarring. Where is the data for new cancers?
Update: The above post was updated on January 20, 2012 by providing the full name for the second scientist involved in the discussion after receiving his permission.