The basic assumption in radiation protection is that stochastic risk is directly proportional to dose. Underground laboratories give the opportunity to test the linear no-threshold (LNT) model for which below the averave natural environmental background no detriment is expected.

Ref:Maria Antonella Tabocchini, The underground biology at the INFN Gran Sasso National Laboratory. Fifth International Workshop for the Design of the ANDES Underground Laboratory Towards the ANDES laboratory flag-ship and further experiments Buenos Aires, Argentina 29-30 June 2017.