Dose-response relation for chromosomal aberrations in irradiated human lymphocytes

The linear-quadratic equation (LQE) was fitted to the frequency of dicentrics and rings produced by gamma irradiation in human lymphocytes in different dose ranges. It was found that at higher doses the linear term of the LQE increased whereas the quadratic term decreased. The same regularity was observed when the results of other authors were subjected to the same analysis. This result questioned the validity of the 'dual theory' for interpretation of the production of chromosomal abberations, and the LQE appeared to be inadequate for extrapolation of effect to low doses. The dose-response relation was studied experimentally at low doses using a sufficient number of doses and cells. An anomalous response at low doses, not predicted by the existing theories, was found. The mechanism underlying the shape of the dose-response curves is discussed. (author)