Colleagues:

 

We have used WinBUGS to implement fitting of a biological-based model to data for low-dose radiation induced stochastic biological effects (neoplastic transformation) in cells.  The mechanistic model involves four parameters which I will simply refer to here as A, B, C, and D and can yield hormetic-type dose-response relationships.  When A and B both equal zero, the model is identical to the linear, no-threshold (LNT) model used in low-dose cancer risk assessment.  In implementing our Bayesian analysis with WinBUGS, we have counted by iteration the posterior data sets (after discarding the burn-in) generated for which both A and B were zero.  This occurred 2 out of each 1000 iterations (total 20000 iterations).  We interpret these results to favor a dose-response shape other than associated with the LNT model.  Are we correct to assign a p value =2/1000 (or p < 0.01) for rejecting the LNT model?

 

Any comments you may have would be appreciated.

 

B. R. Scott

LRRI, Albuquerque, NM, USA