 THC in saliva is said to be an index of recent cannabis smoking and closely linked to the effects of intoxication however in another study, volunteers were recruited to consume cannabis and subsequent levels of THC taken from saliva.The amounts detected were only above the level of the DrugWipe at 10 ng/ml for 70 minutes with volunteers reporting feeling intoxicated for a further 2 hours.As this 1999 DEA Bulletin shows, Drugwipe is still effective when testing 'Black Cocaine' even when chemical tests fail to detect.