Saturday, August 27, 2011

A Short History of "Risk" Assessments for Radiation Exposure

Majia here: I would like to provide a very brief history of government, academic, and industry efforts to establish radiation risk assessments. This is a terrible history. I am only relying on 2 sources in my brief discussion but will provide suggestions for further reading.

My first source: Permissible Dose: A History of Radiation Protection in the 20th Century by J. Samuel Walker published in 2000 by University of California Press.

Regarding limits to radiation doses to the population, Walker explains: The International Commission on Radiological Protection (ICRP) 1953 “recommendation on the issue were arbitrary and tentative” although they represented the first formal efforts to establish radiation protection (p. 12)
Majia here: I think it interesting to examine the kind of research approved and supported by government agencies such as the AEC on radiation exposure in the 1940s through 1960s.

The United States Atomic Energy Commission, established by the Atomic Energy Act of 1946, sponsored experiments between 1945 and 1947 where 18 patients “received injections of plutonium as a part of efforts to calibrate body burdens… The researchers did not expect that the patients would receive any therapeutic benefits from the plutonium they received and made a deliberate effort to prevent them from learning about their unwitting participation in the experiments” (p. 16).

In 1946 and between 1950 and 1953, the AEC working, with the National Institutes of Health and the Quaker Oats Company, funded research carried out by MIT scientists
that fed radioactive iron or calcium to students at the Walter E. Fernald School, an institution for mentally retarded children in Massachusetts…as in the case of the plutonium injections, the experiments were not designed or expected to provide any health benefits to the subjects.
Although the school asked parents of the children to sign a consent form, the information it offered was neither completely frank about the purpose or the possible risks of the tests. Indeed, it misleadingly suggested that the experiments could improve the children’s condition” (p. 17)
Majia Here: Can we trust government and nuclear industry data when this kind of history exists?

In this interview, Dr. Chris Busby explains how the current dominant model of radiation risk was formed.

Busby explains that the ICRP model “doesn’t work” –“if you predict number of cancer after an exposure to internal radionuclides you get the wrong answer
He explains that the model was first set up in 1952—before the discovery of DNA (discovered in 1953)
The ICRP model was set up to look at the health effects from radiation exposures from the manufacturing of atom bombs
Busby notes that the model took and is still premised in a “physics based approach” because mostly physicists were involved in this early research.
Busby believes that the limitations of the model stem from the physicist’s approach to understanding the material world: they “reduce everything to the simplest format in order to get a mathematical equation
Busby notes that you cannot make a mathematical equation about a person that is too complicated

Therefore, the physicists involved in producing the model essentially “turn[ed] a person into a bag of water and then they said that the exposures had to be regulated on the basis of the amount of energy that was transmitted into the bag of water

The model for studying the internal effects of radiation – the absorbed dose – entailed:
A bag of water in the shape of a person”

“Put a thermometer inside it”

“Fire radiation at it and you see if the temperature goes up”

“And that enables you to define absorbed dose

Busby argues that the objective of the ICRP was to deflect public concern about radiation exposure, despite the agency’s claim that it is not promoting anything.
Busby says that when the public raised concern about cases of childhood leukemia, the ICRP could use the model of absorbed dose to state, for example, that the levels of strontium 90 found in milk have “Nothing to do with nuclear weapons because we can tell you the doses are too low
Busby goes on to say that when the doctors started to complain about the health risks of radiation in the 1950s, the World Health Organization was forced into an agreement with the IAEA (1959) dictating that only the IAEA was responsible for studying radiation and health. The agreement precluded the WHO from studying health effects of radiation (or from publishing any research on the subject).

Busby concludes: “ICRP was there to kind of like control the understanding of risk and they still are, they still are


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