Candidates are not allowed to leave the testing room until the test is finished. This ensures that the urine samples collected are not tampered or diluted. However, on-site collection is awkward especially for women because the candidates are actually supervised while collecting their samples. The testing of oral fluid or saliva is also implemented but not popular. Though oral fluid can be collected easily and are not susceptible to alteration, results based on this test are still suspicious. This is because drug traces in saliva can be undetectable after a day. Hence, if a user stops taking drugs a day or two before the test, he may be given a negative mark and pass the test.
Newer technology in drug tests now allow for hair testing. In the present, this is regarded as the most foolproof drug test. Drug residue from drug use, whether ingested or injected, remains inside the hair cuticle. Even if the user bleached, colored, or cut his hair, the residue would still be present and can be detected.
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