Application Of Sewage Pipeline Backtracking Method To Identify Urban Suspected Spots Of Illicit Drugs

With the growth of population,urbanization and income,the drug market presents a trend of gradual expansion.The monitoring and management of drug abuse has always been the focus of the government’s work,but the traditional epidemiological survey methods will consume too many resources.Wastewater-based epidemiology methods can continuously and accurately monitor sampling areas in real time.Although wastewater-based epidemiology enables largescale and long-term monitoring of regional toxicity,it hasn’t a method yet on how to precisely identify and judge key information such as drug consumers clustering points or poison production dens in a certain area.In this study,according to the layout of municipal sewer network,we used sewage pipeline backtracking method to trace and collect sewage samples.And we used liquid chromatography mass spectrometry to analyze the concentrations of the population marker cotinine and five typical drugs,methamphetamine,heroin,ecstasy,ketamine,as well as cocaine in wastewater.Then,we identified outlier sampling sites in the detection areas,analyzed hospital and suspected drug manufacturing lab samples,and conduct a regional aggregate judgment of poison conditions.In this study,98 sewage samples were collected from 8 administrative districts of a city,including 13 sewage treatment plant influent samples and 85 sewage pipeline backtracking point samples.After the pretreatment of solid phase extraction,the computer analysis was carried out by liquid chromatography-mass spectrometry.The results showed that the concentration of cotinine in the influent of the sewage plant was significantly lower than that in the sewage at the backtracking point of the pipeline(p < 0.01);There was no significant difference in the concentration of drugs and their metabolites between the influent of the sewage plant and the sewage at the backtracking point of the pipeline(p > 0.05).Using Nair test,it is identified that methamphetamine has 5 outliers,heroin has 3 outliers and cocaine has 3 outliers.The drug concentration in the sewage at the outliers is significantly higher than that at other sewage backtracking points(p < 0.05),indicating that there is a gathering of drug abusers in this area.After in-depth analysis of the anomalies,it was found that hospital sewage has an impact on regional toxicity assessment.We collected 13 hospitals in 3 administrative districts and 3WWTP located in each sampling district for sampling analysis.The results indicated that the five drugs were detected in hospital effluents except ecstasy,and all four drugs had legal sources in hospital sewage.Morphine and cocaine have become the most common drugs in hospital sewage.Among them,the proportion of a regional hospital sewage to the drug quality load of municipal sewage is as high as 84.2% and 75.4%.When tracing the sewage pipeline,it might affect the regional drug situation judgment.Therefore,the drugs from legal sources in the hospital sewage can have an impact on the regional drug research and judgment,so it is necessary to conduct in-depth research and analysis after eliminating its impact.On the basis of preliminary regional research and judgment,it is found that there are abnormal values in buildings in a residential area.Combined with relevant intelligence,we speculate that there is a suspected drug manufacturing lab in a building of the community.We obtained the samples by combining active sampling and passive sampling methods,and then we analyzed these samples.The results showed that the methamphetamine concentration of the building sewage pipe sample(6291 ng/L)was abnormal,and the calculated abuse result was5424 mg/d/1000 inh.This value is far beyond the mean value of local per capita abuse,so we judged the existence of a drug manufacturing lab in this area.According to the analysis of sewage poisoning,the police took action to arrest the drug-manufacturing suspects and seal up the drug-manufacturing factory.In summary,the application of sewer pipeline backtracking method can accurately identify drug use anomalies or drug manufacturing labs and provide technical support for regional toxicity assessment as well as public security drug control work.