Trend analysis of anonymised pooled urine from portable street urinals in central London identifies variation in the use of novel psychoactive substances

Context. There is increasing interest in the analysis of waste water at sewage treatment plants to monitor recreational drug use. This technique is limited for novel psychoactive substances (NPS) due to limited knowledge on their human and bacterial metabolism and stability in waste water. Small studies have reported the detection of NPS using pooled anonymous urine samples, which eliminates some of these potential confounders. Objective. To determine patterns of recreational drug, including NPS, use by confirming their presence in analysis of pooled urine from portable street urinals across a wide geographical area in central London over a 6-month period. Materials and methods. Pooled anonymous urine samples were collected from 12 four-bay stand-alone portable urinals distributed once a month across central London for six consecutive months. Samples were analysed using high-performance liquid chromatography coupled to high-resolution accurate mass spectrometry (LC-HRAM-MS); acquired data were processed against target compound databases. Results. With regards to Classical Recreational Drugs, there was consistency of detection of cathine, cocaine, morphine, MDMA over the 6 months, with variability of detection of amphetamine, ketamine and cannabis. With regards to NPS, a total of 13 NPS were detected during the six months. Mephedrone and methylhexaneamine were detected consistently each month. Other commonly detected NPS included methiopropamine (5 months), pipradrol (4 months), cathinone (4 months), 5-(2-aminopropyl)benzofuran (3 months) and 4-methyethcathinone (3 months). Of note, methoxetamine and the synthetic cannabinoid receptor agonists were not detected in any samples. Discussion. Previous studies using the same method detected three and five NPS in a nightclub and pissoir setting, respectively, on a single night. The longer sampling time of 6 months has allowed detection of 13 NPS. Of note, mephedrone showed the least month-to-month variation in detection over the 6-month sampling period. With regards to classical recreational drugs, those detected were consistent with use-data from UK population surveys. The only exception is amphetamine which these surveys have shown a steady decline in use since 1996 but our study showed some variation in the frequency of its detection. However, the sampling period was too short and a longer study is needed to detect the trend in decreasing use. Conclusion. This study demonstrates that analysis of anonymous pooled urine samples from stand-alone urinals can be used to detect and monitor trends in the use of classical recreational drugs and NPS in a large city centre over time. This technique has the potential to be a novel key indicator alongside other existing indicators to provide a more robust picture of the use of recreational drugs including NPS.