Hair testing is superior to urine to disclose cocaine consumption in driver's licence regranting

In driver licence regranting, subjects with a history of cocaine use are requested to undergo laboratory testing to verify both current and past abstinence from the drug. Identification of cocaine use based only on urinalysis may miss some cases because of the short elimination half-life of the drug. Moreover, many abusers know how to time their cocaine consumption in such a way that they can "beat" the urinalysis, having a series of negative urine tests. We report on the use of hair testing to disclose sporadic cocaine consumption in seven subjects attending the Local Medical Commission to reobtain driver licence, with constant negative urinalysis. Even with one or two weekly negative urine screens along several months, all the subjects were positive using hair testing for cocaine and benzoylecgonine, above the internationally recommended limit of quantification: 0.5 ng/mg and 0.05 ng/mg for cocaine and benzoylecgonine, respectively (concentration range for cocaine: 0.51-2.23 ng/mg hair; concentration range for benzoylecgonine: 0.08-1.70 ng/mg hair). The obtained results support strongly the use of hair testing for cocaine in drug addicts and occasional abusers applying for regranting of driver licence in order to minimize social risk behaviours.