Frequency of new psychoactive substances in hair and urine samples of individuals subject to drug testing in driving license regranting—A toxicological perspective

In recent years, numerous new psychoactive substances (NPS) have emerged on the illicit drug market. The assumed non-detectability of these drugs is often a key motivation for individuals subject to drug testing, such as those in driving license regranting programs. In these programs, NPS are not routinely tested for, and thus, subjects who have to prove abstinence from common drugs of abuse might switch to NPS to avoid positive drug tests. The aim of the study was to determine the frequency of these substances in the hair and urine samples of individuals undergoing drug testing in driving license regranting. A total of 1037 samples (577 hair and 460 urine samples) collected from 949 subjects between February 2017 and December 2018 were retrospectively analyzed for designer drugs and synthetic cannabinoids by liquid chromatography–quadrupole-time-of-flight–mass spectrometry (LC-QTOF-MS). For a more sensitive analysis of synthetic cannabinoids and their metabolites, additional testing was performed by liquid chromatography–tandem mass spectrometry (LC-MS/MS). Overall, 42 hair and two urine samples, which were obtained from 40 subjects, tested positive for NPS resulting in a frequency of 4.2%. While synthetic cannabinoids were detected in all cases, designer drugs were only found in three of these cases. With regard to the 577 hair samples analyzed, 7.3% screened positive, whereas only 0.4% of the 460 tested urine samples contained NPS. The results of this study indicate that synthetic cannabinoid use seems to be popular among this population, and therefore, testing for synthetic cannabinoids should be requested more often preferably using hair analysis.