When scientists speak of radiation, they speak not only of single doses but also of cumulative doses.
See for example, this research from the University of Iowa showing that “cumulative radon exposure is a significant risk factor for lung cancer in women".
And see these studies on the health effects cumulative doses of radioactive cesium. (As I noted on March 29th, the radioactive cesium fallout from Japan already rivals Chernobyl. And the amount of radioactive fuel at Fukushima dwarfs Chernobyl).
Admittedly, the damage from huge single doses may be greater than the same cumulative dose from many small exposures. But the smaller doses can still add up.
Remember, the radiation from CT scans and x-rays are external emitters - the radiation emanates from outside the body. In contract, internal emitters keep emitting their radiation inside the body. Therefore, the cumulative effect of multiple small doses of radiation from internal emitters could be even more dramatic, depending on the half life, metabolic pathways and other properties of the particular radioactive particle.
As the European Committee on Radiation Risk notes:
Cumulative impacts of chronic irradiation in low doses are ... important for the comprehension, assessment and prognosis of the late effects of irradiation on human beings ...
And see this.
A military briefing written by the U.S. Army for commanders in Iraq states:
Hazards from low level radiation are long-term, not acute effects... Every exposure increases risk of cancer.
briefings for commanders often contain less propaganda than literature
aimed at civilians, as the commanders have to know the basic facts to
be able to assess risk to their soldiers.)
The briefing states that doses are cumulative, citing the following military studies and reports:
- ACE Directive 80-63, ACE Policy for Defensive Measures against Low Level Radiological Hazards during Military Operations, 2 AUG 96
- AR 11-9, The Army Radiation Program, 28 MAY 99
- FM 4-02.283, Treatment of Nuclear and Radiological Casualties, 20 DEC 01
- JP 3-11, Joint Doctrine for Operations in NBC Environments, 11 JUL 00
- NATO STANAG 2473, Command Guidance on Low Level Radiation Exposure in Military Operations, 3 MAY 00
- USACHPPM TG 244, The NBC Battle Book, AUG 02
One of the Giant's of Radiation Exposure Science Warned of Cumulative Low-Dose Exposures
American reporter Dahr Jamail reports today for Al Jazeera:
“The U.S. Department of Energy has testified that there is no level of radiation that is so low that it is without health risks,” Jacqueline Cabasso, the Executive Director of the Western States Legal Foundation, told Al Jazeera.
Her foundation monitors and analyzes U.S. nuclear weapons programs and policies and related high technology energy, with a focus on the national nuclear weapons laboratories.
Cabasso explained that natural background radiation exists, “But more than 2,000 nuclear tests have enhanced this background radiation level, so we are already living in an artificially radiated environment due to all the nuclear tests.”
“Karl Morgan, who worked on the Manhattan project, later came out against the nuclear industry when he understood the danger of low levels of ionizing radiation-and he said there is no safe dose of radiation exposure,” Cabasso continued, “That means all this talk about what a worker or the public can withstand on a yearly basis is bogus. There is no safe level of radiation exposure. These so-called safe levels are coming from within the nuclear establishment.”
Karl Morgan was an American physicist who was a founder of the field of radiation health physics. After a long career in the Manhattan Project and at the Oak Ridge National Laboratory, he became a critic of nuclear power and weapons. Morgan, who died in 1999, began to offer court testimony for people who said they had been harmed by the nuclear power industry.
“Nobody is talking about the fact that there is no safe dose of radiation,” Cabasso added, “One of the reasons Morgan said this is because doses are cumulative in the body.”
As the Guardian wrote in Morgan's obituary in 1999:
Karl Morgan ... was a pioneer of health physics - the science of the effect of exposure to radiation on health. He was a member of the research group which laid the foundations for the Manhattan project and produced the first atomic bomb. However, after 30 years in the inner cabinet of the nuclear establishment, Morgan changed sides and testified in key radiation cases on behalf of those who claimed they had been harmed by nuclear weapons and the nuclear power industry.
The first signs of his change of view came in 1968, when he became an influential campaigner in obtaining a US law that required the medical profession to control excessive doses of radiation during X-rays.
After retirement in 1972 he became more active in drawing attention to the limitations of radiation protection measures.
He began his career as a physics professor but in 1943 was recruited to become a senior scientist in health physics to the top secret, atomic bomb project codenamed Manhattan Engineer District.
The following year, Morgan went to the newly-formed Oak Ridge national laboratory in Tennessee, where he became director of health physics from 1944 until his retirement. When told he would be in the health physics group, he was shocked and said it was a terrible mistake because he had never heard of health physics. The leaders of the research project said they had been in the same position. But they realised that since their attempts to build the first atomic pile, now known as a reactor, would create a source of intense radiation, they needed to understand how to protect people.
He wrote in his autobiography, The Angry Genie: One Man's Walk Through The Nuclear Age, that he did not believe they had ever determined that it was safe. "We determined what we considered was acceptable."
The Townsend Letter for Doctors & Patients wrote in 2002:
One of the original five ‘health physicists' to set radiation safety standards was Karl Z. Morgan. Dr. Morgan served on the International Commission on Radiological Protection (ICRP), which set up most radiation standards. He also directed the Health Physics Division at Oak Ridge from 1944 until his retirement in 1972. In recent years, Dr. Morgan has publicly criticized the ICRP for failing to protect human health. In a 1994 article for the American Journal of Industrial Medicine, Dr. Morgan wrote: "The period of atmospheric testing of nuclear weapons by the United States, the United Kingdom, France and the USSR is a sad page in the history of civilized man. Without question, it was the cause of hundreds of thousands of cancer deaths. Yet there was complete silence on the part of the ICRP. During these years (1960-1965), most members of the ICRP either worked directly with the nuclear weapons industry or indirectly received most of their funding for their research from this industry.”
The ICRP's alliance with the nuclear industry includes ties to the International Congress of Radiology. In his 1999 autobiography, The Angry Genie: One Man's Walk Through the Nuclear Age (ISBN 0-8061-3122-5), Dr. Morgan related his concern about the ICRP's refusal to address the danger of excessive X-ray exposure during diagnostic procedures and dentistry. Until the passage of the Radiation Control for Health and Safety Act of 1968, some X-ray equipment used in the 1950s and 1960s delivered 2 to 3 rem per X-ray. X-ray doses as low as 1.6 rem increase a woman's chance of developing cancer, according to a 1974 study by Baruch Modan [Lancet (Feb. 23,1974), pp 277-279]. The Act did not address the cumulative effect of multiple, routine, and often unnecessary X-rays.
We would be wise to heed Karl Morgan's insights.