Hair analysis for drugs in driver's license regranting. A Swedish pilot study

When being convicted for petty drug offence or driving under the influence of drugs in Sweden, the driving license may be suspended. To regain the license, the person has to prove that he or she has been drug free during an observation period. This is controlled by urine samples taken at several occasions. However, the risk of manipulation and the risk of false negative urine samples are high. In addition, many people find it difficult or embarrassing to urinate when observed. Hair sampling might therefore be a welcome option to this procedure, with its easy sampling and minimal risk of manipulation. The longer detection window may also provide better information to the physician. The aim of this work was to evaluate if clients preferred hair samples to urine and to investigate practical and interpretive problems or advantages with hair samples. Ninety-nine hair samples and 198 urine samples were collected from 84 clients during the 12 month study period. Hair samples were divided into either one segment (0-3 cm) or two segments (0-3 and 3-6 cm) depending on the length. The hair samples were screened with LC-MS-MS for 20 drugs and confirmation of positive results were performed with GC-MS or LC-MS-MS. The results were compared to urine samples taken at two occasions during the observation period. To cover the timeframe of the urine samples hair was collected 2 weeks after the second sample. The urine samples were analysed with immunochemical screening and positive results confirmed with GC-MS or LC-MS-MS. Seventy-four clients presented with negative results in both urine and hair. Hair analysis identified illegal drugs at seven different occasions whereas urine failed to identify any illegal drugs. However the thresholds used may still be too high to find sporadic use as clients that admitted to use drugs sporadically presented with drug concentrations lower than the agreed thresholds but above the limit of detection. This implicates that the physician must have an understanding and knowledge of the limitations of the screening methods used. Another important outcome was that the clients approved of hair sampling considering it a better means to prove their drug abstinence. In addition, both the clients and the clinicians thought hair sampling easier than urine sampling. We believe that hair analysis can offer several advantages compared to urine analysis for clinicians working with driving license regranting.