In risk assessment, the “point of departure” is the dose selected as the starting point to which uncertainty or safety factors are applied to derive a “safe” dose.

See the EPA’s definition of “point of departure” on their website »

Historically, this starting point is either the No Observed Adverse Effect Level (NOAEL) or the Lowest Observed Adverse Effect Level (LOAEL). The use of a No Observed Effect Level (NOEL) is a dramatic departure from current policy and constitutes a much more conservative starting point than has been used for any other regulated chemical.