Analysis of drugs of abuse in wastewater from two Canadian cities

Abstract

Several drugs of abuse, including amphetamines, cocaine and its metabolite, benzoylecgonine and several opioid prescription drugs were detected in wastewater from two Canadian cities, a small community (75,000 population) and a large urban center (1.6million population). The objective of this study was to evaluate community use of these drugs in two cities with large differences in population size and demographics. In addition, we evaluated the use of the Polar Organic Chemical Integrative Sampler (POCIS) as a monitoring tool for drugs of abuse. Heroin was not detected at either location, probably because this illicit drug is metabolized to morphine prior to excretion. Acetylcodeine and acetylmorphine were also not detected. Estimates of community consumption from wastewater analysis indicated that the most widely used drug was cocaine at a median level of consumption in the larger city of approximately 38 doses per day per 1000 people. Consumption of the substituted amphetamine, ephedrine, as well as methamphetamine was also higher in the larger city, at 21 and 1.8 doses per day per 1000 people, respectively. Use of amphetamine, MDMA and tramadol were similar in both centers, but use of oxycodone was greater in the smaller city. Use of MDMA (ecstasy) peaked on weekends. Ketamine was detected in wastewater from the larger city; the first report of abuse of this veterinary anesthetic in a North American city. POCIS sampling rates were determined for the first time for 7 of the target compounds. Comparing the time weighted average concentrations estimated from POCIS data to the concentrations obtained from 24-h composite samples, the data were generally comparable, except for some compounds which were not detected in POCIS deployed in the untreated wastewater, probably because of biofouling or accumulation of debris on the cages containing the POCIS. This study indicates that the size and demographics of population centers can influence the patterns of abuse of drugs.