Estimated risk of liver cancer due to. cap alpha. emitters and. beta. -. cap alpha. emitting parent-daughter chains: an application of Thorotrast data

Thorotrast dose-effect relationships have been used here to estimate the potential impact of chronic exposure to transuranium elements. As yet, only liver cancer has been considered. If epidemiological data are developed for other cancers, such as bone sarcoma, these methods can be extended. Uncertainty in the childhood sensitivity introduces more variation in health effects estimates for radiation exposure than that introduced by the selection of the health risk model or any other case parameter. Thus it is still important to refine the Thorotrast data on liver carcinoma further. Identification of the latent period from exposure to first development of cancer and quantification of the sensitivity of children relative to adults are of primary importance. Of lesser importance for this cancer are the duration of the risk plateau and whether the risk is best estimated by use of an absolute or a relative risk model. Health effects estimates would be improved if the Thorotrast data could be analyzed to provide age-specific data on the cancer risk. In that case, it might be possible to judge whether the absolute risk or relative risk model is more appropriate. Of even more importance would be the determination of the time to occurrence and age-specificmore » risk as a function of age at the time of exposure, particularly for the young. Obtaining adequate estimates of these parameters will require use of not only data on Thorotrast patients but also on matched controls, although vital statistics for the general population of the country of interest might be sufficient. A continuing effort should be made to bring all Thorotrast studies to a degree of consistency where reasonable estimates of age-specific and total risk of all cancers can be made.« less