Simulated responses to lognormally distributed continuous low radiation doses.

Three previously reported equations, expressing response as a function of both dose and dose rate, for low LET radiation were used to compute distributions of response to continuous, low-level, lognormally distributed doses for populations of variable size up to 5000. The simulations show that, when the response is inversely dependent on dose rate, the mean of the response distribution can either increase or decrease with increasing exposure to radiation, depending on whether or not the dose-dependent term is the dominant one in an equation. In one equation, which defines the response as conjugated hydroperoxide formation in irradiated membranes, the magnitude of the dose-dependent term is reduced the most by superoxide dismutase, an enzymic inhibitor of free radical processes. This results in the means of response distributions decreasing with increasing dose from continuous, low-level radiation.