Impact of degradation products of sulfamethoxazole on mammalian cultured cells.

Sulfamethoxazole (SMX) is a widely used antibiotic which has been detected in surface water samples in the ng/L range and also detected in drinking water samples. To limit the environmental impact, ozonation treatment of waste streams has been proposed. However, the degradation products created by ozonation as well as their toxicity have not been reported. In this study, we investigated the degradation products of SMX formed during ozonation and the effects of these products on mammalian cultured cells. In addition to alcohols and nitrates, sulfanilamide was identified as the larger molecular weight compound of the degradation products detected. Cells exposed to the degradation products of SMX maintained their polyhedral geometry longer than the control cells. Proliferation of the cells exposed to the degradation products was not negatively affected when compared with the control cells. The results of this study show that bioactive degradation products can be formed by ozonation of SMX.

Linking drugs of abuse in wastewater to contamination of surface and drinking water.

The concentrations of 17 drugs of abuse, including cocaine, several amphetamines, opioid drugs, and 2 metabolites--benzoylecgonine, a metabolite of cocaine, and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrolidine, a metabolite of methadone--were investigated in an urban watershed that is heavily impacted by discharges of municipal wastewater. The artificial sweetener sucralose was also monitored as a persistent tracer of contamination from municipal wastewater. Monitoring was conducted in a municipal wastewater treatment plant (WWTP) and at sites upstream and downstream of the WWTP discharge, as well as in a drinking water treatment plant (DWTP) located 19 km downstream of the WWTP discharge that withdraws raw water from the river. Drug concentrations were monitored with polar organic chemical integrative samplers deployed for 2 wk in the river and in the WWTP and DWTP. Several of the investigated compounds exhibited a decrease in concentration with distance downstream from the wastewater discharge into the river, but there was little attenuation of sucralose, cocaine, benzoylecgonine, morphine, acetylmorphine, acetylcodeine, and oxycodone. Heroin and methadone were not detected at any sample locations. Amphetamine, methamphetamine, 3,4-methylenedioxy-methamphetamine, and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrolidine were not detected in the samples collected at the drinking water intake. Many of the drugs of abuse were not removed effectively in the DWTP, including cocaine, benzoylecgonine, methylenedioxyamphetamine, ephedrine, and several prescription opioids, most probably because the DWTP was operating at or above its rated treatment capacity. These data indicate that there can be transport of drugs of abuse from wastewater sources into drinking water in urban watersheds.

Impact of approach used to determine removal levels of drugs of abuse during wastewater treatment.

In this study the levels of 19 drugs of abuse were estimated throughout a wastewater treatment plant using polar organic chemical integrative samplers (POCIS), 24h composite samples and grab samples. Overall removal efficiencies and removals in between each treatment unit were calculated using load data for each sampling technique as well as removals that take into account the hydraulic residence time distribution of the treatment plant (time-shifted mass balancing approach). Amphetamine-type stimulants, cocaine and its major metabolite, benzoylecgonine and opioid levels determined with 24h composite samples were generally comparable to those obtained with POCIS and grab samples. Negative mass balances resulting from the estimation of overall removal efficiencies by POCIS, day-to-day mass balancing of 24h composite and grab sample data did not occur when the hydraulic retention time (HRT) distributions of the plant were taken into account for calculation. Among the compounds investigated, cocaine exhibited the highest overall removal (90%) while codeine had the lowest with 13%, respectively. Sampling between the treatment units revealed that highest removal occurs during biological treatment as compared to primary or secondary clarification. Methylenedioxyamphetamine (MDA), fentanyl, dihydrocodeine and heroin were not detected in wastewater at any of the sampling locations at the treatment plant regardless of the sampling technique. The study demonstrates the benefits of applying the time-shifted mass balancing approach to the calculation of removals of drugs of abuse during wastewater treatment.

Ozonation of wastewater: removal and transformation products of drugs of abuse.

In this study amphetamine, methamphetamine, methylenedioxymethamphetamine (MDMA), cocaine (COC), benzoylecgonine (BE), ketamine (KET) and oxycodone (OXY) in wastewater at concentrations of 100 µgL(-1) were subjected to ozone to determine their removals as a function of ozone dose and to identify significant oxidation transformation products (OTPs) produced as a result of ozonation. A method based on high resolution mass spectrometry and differential analysis was used to facilitate and accelerate the identification and structural elucidation of the transformation products. The drug removal ranged from 3 to 50% depending on the complexity of the matrix and whether a mixture or individual drugs were ozonated. Both transient and persistent oxidation transformation products were identified for MDMA, COC and OXY and their chemical formulae were determined. Three possible structures of the persistent transformation product of MDMA (OTP-213) with chemical formula C10H16O4N, were determined based on MS(n) mass spectra and the most plausible structure (OTP-213a) was determined based on the chemistry of ozone. These results indicate that ozone is capable of removing drugs of abuse from wastewater to varying extents and that persistent transformation products are produced as a result of treatment.

Analysis of drugs of abuse in wastewater from two Canadian cities.

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 (1.6 million 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.

Oxidation products of sulfamethoxazole in ozonated secondary effluent.

In this study the antibiotic sulfamethoxazole (SMX) was subjected to ozone treatment. Solutions of 60 mg/L and 100 microg/L SMX in pure water and secondary municipal effluent were treated. The removal profile of SMX and its oxidation products was monitored as a function of transferred ozone dose in both matrices. No difference was observed in the ozone dose required for the concentration of SMX to fall below the limit of detection in pure water and wastewater. New peaks with the same retention times were obtained on the HPLC chromatograms for all conditions studied. Solutions with an initial concentration of 60 mg/L required 83 mg/L of ozone to fall below the limit of detection and eight oxidation products were detected. Solutions with an initial concentration of 100 microg/L required 14 mg/L of ozone and only four oxidation products were detected. The four peaks obtained during experiments at low concentration were observed at the same retention times as four of the peaks obtained in higher concentration samples. In ozonated wastewater these products were identified as: 4-aminobenzene sulfonamide, N-(3-phenylpropyl)-acetamide, 2-methyl-benzoxazole and phenol. In addition, methanol, ethanol, acetic acid, methyl acetate and ethyl acetate were identified in the higher concentration samples.

Illicit drugs in Canadian municipal wastewater and estimates of community drug use.

In this study of wastewater treatment plants in three Canadian cities, selected illicit drugs, including cocaine and its major metabolite, benzoylecgonine (BE), amphetamine, methamphetamine and ecstasy (i.e. MDMA) were detected in untreated wastewater. Cocaine was the most widely used illicit drug at a median level for the 3 cities of 15.7 doses per day per 1000 people. For the other drugs, the median doses per day per 1000 people were 1.8 for amphetamine, 4.5 for methamphetamine and 0.4 for ecstasy. Methamphetamine use was highest in the largest city and cocaine use was lowest in the smallest city. Removal of the illicit drugs by wastewater treatment was generally >50%, except in a WWTP that uses primary treatment. The community consumption estimate for ecstasy in the present study is far below published estimates of the prevalence of ecstasy use among the Canadian population, which may be due to only occasional use of ecstasy.