Benzodiazepines in a Health-Catalog Product

To the Editor.—  A manufacturing company in the Northwest administered a routine preemployment drug test to a 56-year-old engineer. Its results were reported to the medical review officer by the testing laboratory as "positive for benzodiazepines" with the finding of oxazepam, 310 ng/mL, and nordiazepam, 150 ng/mL, on gas chromatography—mass spectrometry confirmation.The prospective employee convincingly denied any use of a prescription medicine, including a benzodiazepine. A repeated test was requested on the retained positive urine sample. It too was reported positive for a benzodiazepine.The prospective employee reported that he had regularly used a nonprescription health product obtained by catalog from a California address. It was a dark-brown, round pill labeled "NAN-LIEN CHUIFONG TOUKUWAN" that had been recommended to him by a colleague at work to treat his chronic neck pains. A sample submitted to the laboratory was analyzed by fullscan gas chromatography-mass spectrometry (Hewlett-Packard 5970). It was