To the Editor.
—Workplace drug testing continues to be a major issue in the United States. As commentators debate the propriety of random workplace drug testing, the knowledge base about the process of drug testing continues to evolve.The formal drug testing programs sanctioned by the Department of Health and Human Services and the Department of Transportation rely on a series of security procedures to discourage the dilution of a specimen or the substitution of a false specimen for a real specimen. One such measure is the placement of bluing in the toilet bowl at the collection site to prevent a specimen "donor" from either substituting toilet water for a urine specimen or diluting a real urine specimen with toilet water.1We would like to remind practitioners in the field, especially physicians working as medical review officers, that there are legitimate medications that contain methylene blue (Prosed, Webcon Pharmaceuticals,
Clark HW, Sees KL. Drug Testing and the Toilet Bowl Blues. JAMA. 1992;268(17):2377. doi:10.1001/jama.1992.03490170049020