9906a3Logan-ANS99

3. Recognition of Threshold Dose Model: Avoiding Continued Excessive Regulation,

"The purpose of this work is to examine the relationships between radiation dose-response models and associated regulations. The objective of radiation protection regulations is to protect workers and the public from harm resulting from excessive exposure to radiation. The regulations generally stipulate various levels of radiation dose rate to individuals or limit concentrations of radionuclides in releases to water or the atmosphere. The cleanup standards applied in remedial action for contaminated sites limit the concentrations of radionuclides in soil, groundwater, or structures, for release of sites to other uses. The guiding philosophy is that 'less' is better and 'none' is better yet. This has culminated with the concept of as low as reasonably achievable (ALARA). In fact, all regulations currently in place are arbitrarily based on the linear no-threshold hypothesis (LNTH) dose-response relationship. This concept came into use several decades ago and simply assumes that the incidence of health effects observed at a high dose or high dose rate will decrease linearly with dose or dose rate all the way down to zero, with no threshold level. Subsequent data have accumulated¹ and continue to accumulate, demonstrating that there is a threshold level for net damage and, further, that there is a net benefit (radiation hormesis) at levels below the threshold level.

"It is determined that continuation of regulations based upon the LNTH imposes doses, dose rates, and environmental concentrations that are excessively low. While alleged to be the safe thing to do, the opposite is the result. Resources are wasted that could be effectively applied in other areas, and the attempt to avoid all low-dose radiation exposure denies realization of benefits from radiation hormesis. Preliminary study by Logan,^2,3 continued in this work, indicates that savings of up to hundreds of billions of dollars per year are potential benefits of revising regulations to a threshold model basis. The benefits arise from reductions in costs of emission control, regulatory enforcement, and waste disposal. Intangible benefits include eliminating the 'no level of radiation exposure is safe' myth, which would greatly reduce public fear, a reduction vitally important to the continued public acceptance of nuclear benefits.

"It may be argued that no change in the basis for regulations should be made until further research into low-dose health effects and their basic mechanisms is completed. Funding for such research was passed by Congress in 1998, and work is under way through the Office of Biological and Environmental Research in the U.S. Department of Energy. One large effort that is part of the International Health Programs⁴ concerns the Mayak Production Association that was established by the former Soviet Union in 1948 in the southern Urals. Large amounts of radioactive material were released to the environment from a series of accidents at this nuclear weapons production complex. A vast database is being accumulated and analyzed by the Joint Coordinating Committee for Radiation Effects Research with U.S. participation. In time, results should further support a threshold model, though some researchers may continue by habit to force-fit selected data to the linear hypothesis. However, many years may pass before the bulk of this new research is completed. In the meantime, continuation of unnecessary excessive regulation continues the unnecessary loss to the public and the economy.

"It is concluded that recognition of the validity of a threshold model can be done on the basis of presently known data and that changes in regulations should be started at this time to avoid further unnecessary losses due to continued excessive regulation. As results from new research come in, refinement of interim values proposed in revised regulations can be incorporated."

1. Low Level Radiation Health Effects: Compiling the Data, Rev. 1, J. MUCKERHEIDE, Ed., Radiation, Science, and Health, Inc., Needham, Massachusetts (Mar. 1998).

2. S. E. LOGAN, “Potential Benefits from Replacing LNT Model with Threshold Model,” Trans. Am. Nucl. Soc., 75, 429 (1996).

3. S. E. LOGAN, “Threshold Dose Model: It’s Time to Line Up Our Ducks)” Trans. Am. Nucl. Soc., 77, 57 (1997).

4. International Health Programs, http://tis-nt.eh.doe.gov/ihp.