Show them these!

Therapeutic Drug Monitoring - Abstract: Volume 30(2) April 2008 p 196-202 Current Developments in Drug Testing in Oral Fluid.

Portable Oral-Fluid Tests Still Unreliable For Pot, Study Says - NORML

Other studies showed tea, and many other commonly ingested substances, can trigger a false positive. If you ran a search, I bet you could find even more studies! - Granny:hippy: