Mechanistic models of bone cancer induction by radium and plutonium in animals compared to humans

Two-mutation carcinogenesis models of mice and rats injected with (239)Pu and (226)Ra have been derived extending previous modellings of beagle dogs injected with (239)Pu and (226)Ra and radium dial painters. In all cases statistically significant parameters could be derived fitting data from several research groups jointly. This also lead to similarly parametrised models for (239)Pu and (226)Ra for all species. For each data set not more than five free model parameters were needed to fit the data adequately. From the toxicity ratios of the animal models for (239)Pu and (226)Ra, together with the human model for (226)Ra, an approximate model for the exposure of humans to (239)Pu has been derived. Relative risk calculations with this approximate model are in good agreement with epidemiological findings for the plutonium-exposed Mayak workers. This promising result may indicate new possibilities for estimating risks for humans from animal experiments.