Across China, local governments have implemented mass surveillance of urine and feces in city sewers to detect drug use; in drug hotspots like Zhongshan, longitudinal assays of drug residues in human waste are used to evaluate the efficacy of anti-drug programs.
Several EU states use assays of sewage in epidemiological studies to evaluate levels of drug use, but China is unique in linking this data to drug enforcement efforts, rather than public health data-collection.
Chinese president for life Xi Jinping has asked the UN to make this standard practice all over the world, and has pledged to double the budget for waste surveillance programs every year for the foreseeable future.
Zhang Lei, an environmental policy researcher at Renmin University in Beijing and a collaborator with Li, notes that WBE studies are a more objective way of measuring whether government initiatives to reduce drug use in the community are working. She says that solely relying on traditional methods of monitoring changes in drug use, such as the number of arrests of users or the number of drugs being seized by police, can be misleading because they are indirect measures. "WBE offers an unequivocal measure of the effectiveness of efforts," says Zhang.
Li and his team put this to the test when they measured two popular synthetic drugs, methamphetamine and ketamine, in waste water across China two years after local and national agencies launched campaigns to crack down on drug use and manufacturing in 2013. Zhang's team found that following these initiatives, methamphetamine use dropped by 42% and ketamine use decreased by 67%. Li thinks the drop in drug use is a result of police campaigns.
China expands surveillance of sewage to police illegal drug use [David Cyranoski/Nature]