Norwegian Institute for Water Research (NIVA), Oslo, Norway.
Water Res. 2013 May 1;47(7):2129-40. doi: 10.1016/j.watres.2012.12.034. Epub 2013 Jan 31.
The quantitative analysis of human urinary metabolites as biomarkers in wastewater streams has been used to estimate the rates of illicit drug use in the wider community. The primary underlying assumption in such studies is that a sample of wastewater is equivalent to a cumulative sample of urine. Drug metabolism in humans is predominantly enzymatically mediated, but these processes are not exclusive to the human body, and are found to occur in the environment and the sewer network. Understanding what happens to drugs and their urinary metabolites in the sewer system between the point of excretion and sampling is particularly important since it is possible that in-sewer transformation may influence final biomarker concentration. The present study uses batch experiments to measure and assess the biotransformation processes of cocaine and its two major human metabolites, benzoylecgonine and ecgonine methyl ester. The activated sludge modelling framework for xenobiotic organic micro-pollutants (ASM-X) is used for model structure identification and calibration. Biotransformation was observed to follow pseudo first-order kinetics. The biodegradation kinetics of cocaine, benzoylecgonine and ecgonine methyl ester is not significantly affected by the availability of dissolved oxygen. Results obtained in this study show that omitting in-pipe biotransformation affects the accuracy of back-calculated cocaine use estimates. This varies markedly depending on the in-sewer hydraulic retention time, total biomass concentration and the relative concentration of each metabolite. However, back-calculated cocaine use estimates derived from wastewater concentrations of benzoylecgonine and ecgonine methyl ester do show very close agreement if ex-vivo biotransformation of these compounds is considered.
人类尿液代谢物作为废水中的生物标志物进行定量分析，已被用于估计更广泛社区中非法药物的使用速率。在这些研究中，一个主要的基本假设是，废水样本等同于尿液的累积样本。人类的药物代谢主要是酶介导的，但这些过程并非人体所独有，在环境和污水管网中也有发现。了解药物及其尿液代谢物在排泄和采样点之间的污水系统中发生了什么变化非常重要，因为在污水管道中发生的转化可能会影响最终的生物标志物浓度。本研究使用批量实验来测量和评估可卡因及其两种主要的人体代谢物苯甲酰可卡因和ecgonine 甲酯的生物转化过程。用于外来有机微污染物的活性污泥建模框架 (ASM-X) 用于模型结构识别和校准。生物转化遵循拟一级动力学。可卡因、苯甲酰可卡因和 ecgonine 甲酯的生物降解动力学不受溶解氧可用性的显著影响。本研究的结果表明，忽略管内生物转化会影响反算可卡因使用量的准确性。这在很大程度上取决于污水管中的水力停留时间、总生物量浓度以及每种代谢物的相对浓度。然而，如果考虑这些化合物的体外生物转化，则从废水中苯甲酰可卡因和 ecgonine 甲酯浓度推导出的可卡因使用量估计值非常吻合。
