Hey Eve,
I don’t know what country or part thereof that your brother lives in, but all drug tests here in California are done the same way;
They test your hair! It will give them an accurate test that will go back for months. Oh, and forget the shaved head thing. When I asked the last time I had to drug test, “What do you do with Bald Men?” They said, there are hairs on the rest of the body, we just take them from there.
Tell your bro to suck it up and stop the pot and look for something else!
James in San Diego