Oral fluid consists of saliva and many other fluids such as sputum from the lungs and throat as well as nasal drainage etc. Drugs will permeate the body irrespective of whether they are ingested, snorted or swallowed. Therefore any oral fluid can be used for drug testing. 
 
Oral fluid is very close to blood serum, so if it’s in the oral fluid it’s in the blood. And it follows, if it’s in the blood it’s in the brain too, and so the person is deemed ‘at risk’ due to the drug.  Technology for oral fluid drug testing has improved over the years but TDDA believes that oral fluid testing still has a long way to go so as to be relied on in any case that may involve punitive action against an employee.
 
Please note that currently there are no oral fluid screening devices in the world that can achieve the target concentrations listed in Standard AS 4760-2006 which is the Oral Fluid standard.