Assigned shares in compensation for radiation-related cancers.

At the request of Congress, a Working Group of the National Institutes of Health prepared radioepidemiologic tables which estimate the likelihood that cancer victims previously exposed to a dose of radiation developed their cancer as a result of this exposure. The ultimate purpose of the tables is to provide a scientific basis for determining compensation for such victims, and their use would represent a marked departure from the current tort system for deciding compensation. The preparation of radioepidemiologic tables requires extensive mathematical modeling because matters such as sex, size of dose, age at exposure, type of cancer, and age at diagnosis must be taken into account. The limited data require many assumptions about the quantitative relationship between radiation dose and the age-specific incidence rate of cancer. After partitioning a population into reference sets based on age at exposure, size of dose, type of cancer, etc., an assigned share is computed for each reference set and then assigned to all of its members. The assigned share represents the fraction of the cancer cases in the reference set that are attributed to the radiation dose. Because the population can be partitioned in many ways, each individual's assigned share depends on the partition used and will change with different partitions. Options for modeling and limitations in epidemiologic data lead to considerable uncertainties in estimates of assigned shares that have been scientifically evaluated for the Working Group's tables. In contrast, the uncertainties associated with the current approach for determining the likelihood that a claimant's cancer was caused by radiation have not been appraised, but are likely to be even greater than those associated with the Working Group's tables. One issue is how to use such tables to compensate victims. Some among many possibilities are: to use them together with a compensation formula to determine the fraction of a standard award to be given; to use them as a starting value for the fraction, to be modified by an authority on the basis of additional information supplied by the claimant and defendant; and to use them as input to the present compensation system.