Temporal trends in drug use in Adelaide, South Australia by wastewater analysis

Analysis of municipal wastewater for drug metabolites can reveal the scale of drug use within communities. An Australian city with a population of 1.2 million inhabitants was assessed for 4 stimulants: cocaine, methamphetamine, 3.4-methylenedioxymethamphetamine (MDMA) and amphetamine; 6 opioids: codeine, morphine, heroin, fentanyl, oxycodone and methadone; 11 new psychoactive substances (NPS); benzylpiperazine (BZP), trifluoromethylphenylpiperazine (TFMPP), methcathinone, methylone, mephedrone, methylenedioxypyrovalerone (MDPV), alpha pyrrolidinopentiophenone (alpha-PVP), paramethoxyamphetamine (PMA), 25C-NBOMe, 25B-NBOMe, 25I-NBOMe; and cannabis, for up to four years between December 2011 and December 2015. Temporal trends revealed increasing usage rates of methamphetamine, cocaine, oxycodone, and fentanyl, while decreasing rates of use were observed for MDMA, BZP and methylone. Use of other opioids and cannabis was generally stable across years, while use of new psychoactive substances fluctuated without an apparent direction. Opioids and cannabis were used at a consistent level through the course of the week, while use of stimulants and some NPS increased on the weekend. Seasonal differences in use were observed for MDMA and cannabis (p $_amp_$lt; 0.05) where, on average, MDMA use was approximately 90% higher in December than in other months and cannabis use was approximately 45% lower in each February. Residual month-to-month variability measures on trend-free data showed NPS use had higher variability than the stimulants and opioids. Frequent wastewater sampling and analysis over prolonged periods has yielded valuable insights into long-term drug use trends, in some instances revealed important within-year trends, and demonstrated the differing patterns of use of drugs on weekends compared to weekdays.