Reduction in methamphetamine consumption trends from 2015 to 2018 detected by wastewater-based epidemiology in Dalian, China

Background: Wastewater-based epidemiology (WBE) has become a useful tool in long-term or short-term continuous monitoring of illicit drugs consumption over the world.

Methods: We investigated the trend of methamphetamine (METH) use between 2015 and 2018 through WBE in Dalian, a typical Chinese city. Samples were collected in 11 municipal wastewater treatment plants (WWTPs). An analytical method, solid-phase extraction combined with trifluoroacetic anhydride derivatization prior to gas chromatography-mass spectrometry (GC-MS) analysis was applied to detect METH concentrations.

Results: During the sampling period, the METH concentrations increased slowly from 315 ± 243 ng/L in 2015 to 523 ± 549 ng/L in 2016, followed by a significant decrease with the concentrations 188 ± 187 ng/L in 2017 and 54.6 ± 42.9 ng/L in 2018. Ammonium nitrogen (NH₄-N) was applied to estimate population size. The average coefficient of variation for population in 11 WWTPs was 35.3 ± 8.9%, reflecting the dynamic variations of population effectively. For METH consumption, there was a gradual increase from 2015 (231 mg/day/1000 people) to 2016 (414 mg/day/1000 people) and a significant linear decrease to 2017 (206 mg/day/1000 people) and 2018 (53.9 mg/day/1000 people). The prevalence of METH increased from 2015 (0.78%) to 2016 (1.06%), then decreased to 2017 (0.55%) and 2018 (0.17%), showed similar trends with the consumption.

Conclusions: The obvious reduction trends of METH consumption via WBE over the period in Dalian provides objective evidence for declined METH consumption in local population. The reduction is probably due to the severe crack-down of illicit drugs by the government.