Drug abuse in the workplace.

A program for drug-testing in the workplace requires careful planning. There should be a written policy, detailing for which drugs should there be testing, personnel to be tested, frequency and mode of testing, and sanctions if the tests are positive. Urine collection is best carried out under direct vision, but this may create problems because of invasion of privacy. A chain of custody for the urine specimen must be established and confidentiality of the employee's name maintained. The choice of drugs depends on the employer's objectives, but the illicit "street" drugs should be included. The drug testing laboratory should be carefully selected. Drug screening should be by an antibody method and all positive screening tests must be confirmed by gas chromatography or, even better, by gas chromatography/mass spectrometry. Concentrations of drugs constituting a positive test should be established. These values are usually set by the manufacturers of the reagent kits. Interpretation of positive results should be made by an expert and not by lay staff. Positive results for some drugs may result from prescription medication or food.