5.67. Another commonly used approach to treat uncertainties is to use conservative (cautious) assumptions. For example, when simplifying the models used, a conservative view can be taken. Another example is to assign conservative values to model parameters. This approach has several advantages, in particular for demonstration of compliance with regulatory criteria. However, in some cases, such conservative assumptions may lead to assessments representing situations that are extremely unrealistic or impossible and, therefore, difficult to interpret and communicate. Furthermore, when conservative values are assigned to several parameters, the results of the calculations might be overly conservative and would provide a poor basis for decision making. Another important consideration is that an assumption that is conservative in one scenario, or for one nuclide, might not be so for another; for example, an assumption that overestimates migration of radionuclides from a facility may underestimate the long term risk from intrusion. The conservatism of the assumptions should be justified in relation to their impact on the assessment end points.