How can a DNEL be derived in practice?
Determining DNELs

First, it must be ensured that the substance has similar ADME properties in the tested animal and in humans. In the absence of information, ADME will be considered similar for humans.

If we only have a NOAEL from an oral study in animals, which is the most common experimental route, and we want to switch to another route, such as inhalation or dermal, we will need to take into account the level of absorption (ABS) of the substance by all routes and make an adjustment in order to derive a new NOAEL for the inhalation or dermal routes.