Revision 1
March 19, 1998
by Radiation, Science, and Health, Inc.,
Edited by J. Muckerheide

1.9
Conclusions

"During the last two decades the concepts of radiation protection and the applicable physical quantities have drifted into what must be regarded as chaos. There is increasing evidence that basic assumptions are wrong and that recommended measuring procedures are not only at variance with practice but also often impracticable. While the main responsibility for this situation must be attributed to the International Commission on Radiological Protection (ICRP)..."

"The problems began with ICRP Report 26 (ICRP 1977) which adopted the linear hypothesis. This assumption of proportionality between radiation doses (absorbed or, when indicated, dose equivalent) and any detrimental effects, was, even at that time, at obvious variance with evidence from animal experiments. At the relatively large doses for which statistically uncertain epidemiological data could be obtained it was not clearly refuted, especially when the ‘new dosimetry’ (DS86 1987) was published. However, increasing discrepancies between dose-effect relations obtained at Hiroshima and Nagasaki have not only indicated a much more important contribution of neutrons in the former city; they have also reinforced an earlier impression (Rossi 1980) that there appears to be a reduction of lung cancer mortality at moderate doses at Nagasaki (Yonehara et al. 1995) and a similar reduction suggested (and certainly no increase indicated) in mortality from leukemia at similar doses (UNSCEAR 1994).

"The dubious straight lines drawn through epidemiological data have been extrapolated by factors exceeding 100 despite the complexity of cancer induction and of homeostatic controls. On the basis of ICRP recommendations ‘risks’ from background radiation and occupational exposure were calculated that could not be verified in epidemiological studies.

"In a further step ICRP (ICRP 1978) proposed the effective dose equivalent, which is intended to measure detriment in a linear combination of linear dose-effect relations for various organs. In calculations of the collective dose or the dose commitment, the effective dose equivalent has been evaluated down to the microsievert level. These concepts are untenable unless "risk coefficients" obtained from epidemiology are constant over some five orders of magnitude of the dose."

"At this point bewildered health physicists may agree that the basic issues in radiation protection must be considered de novo including the following principles:

"1. The ICRP derivation of risk coefficients from large doses is unsound and these coefficients are meaningless when applied in routine radiation protection.

"2. Any deleterious effects of background radiation are unmeasurable and there is no sound scientific evidence that they should exist.

"3. Limits to additional radiation exposure of various population subgroups should be based on multiples of the background dose equivalent with the lowest resulting in no less than a doubling of the background level. Background radiation levels are variable but an excess by one or two mSv/y should be considered to be permissible. An occupational permissible dose equivalent that is ten times larger should be acceptable in view of the results of various surveys of radiation workers. .."