There are all sorts of ways to do a drugs test............
hair
pee
saliva
cells scraped from inside the mouth

In fact I remember at Skerries one year a number of competitors were tested when many had to have a sample taken from inside their mouths.
Any sports competitor is liable to be faced with testing at anytime and that includes road racers..............

A big local employer here announced that they would test for drugs as part of the medical for employment word got out it was to be a hair sample that would be taken..............a number of people turned up for the medicial after having very close haircut thinking they would avoid the test................only to find that the nurse asked them to remove their shirts and raise their arm..............oxter hair was just fine thanks.