Legal and illegal drugs in wastewater poses both an ecological and human health challenge as they can make their way into freshwater systems and drinking water sources where they can harm wildlife and pose a human health risk. Now, new research shows that wastewater treatment facilities can play a key role in helping to monitor drug usage, and may ultimately help track drug dealers peddling their contraband.

Swiss scientists recently tested the limitations of using wastewater analysis to crack down on crime. The results of their study was recently published in the journal Forensic Science. The researchers point out that analyzing wastewater to gain a better understanding of drug use is not new — in fact, it even has a name: wastewater-based epidemiology — however, up until now, very little focus has been placed on using this as a mechanism to fight crime. Yet, it can provide pertinent information to law enforcement that can be very useful to help whittle out drug dealers and combat crime.

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Drugs break down within the body, leaving tell-tale traces of metabolites which are excreted as waste. These metabolites can be identified in wastewater, quantified and then back-calculated to determine how much of the drug was originally consumed, as well as provide a good estimate of how many people contributed to the sample. This analysis can provide insight on average drug consumption together with information on changing drug use patterns.

For the study, which focused on the use of methamphetamine, heroin and cocaine in two Swiss cities, the scientists analyzed wastewater and compared it to information received from police intelligence. To get an estimate of heroin usage in the Swiss city of Lausanne, the researchers measured morphine in sewage wastewater and subtracted the amount that was legally prescribed by medical practitioners.

Using this method, from October 2013 to December 2014 the researchers estimated the average daily heroin consumption for the city to be 13 grams. During this period, law enforcement officers arrested two drug dealers. After analyzing their phone records and conducting interviews with drug users, it is estimated that between the two of them, the drug dealers supplied around 6 grams of heroin a day — roughly half the market share. This information provided by the wastewater epidemiology supported police intelligence suggesting that unlike methamphetamine and other drugs, heroin is supplied by just a handful of local drug dealers, who police could target effectively.

As the study so succinctly point out: "You can flush, but you can't hide." "Combined with intelligence resulting from police work (e.g., investigations and informants), wastewater analysis can contribute to deciphering the structure of drug markets, as well as the local organization of trafficking networks," the authors conclude. "The results presented here constitute valuable pieces of information, which can be used by law enforcement to guide decisions at strategic and/or operational levels. Furthermore, intelligence gathered through investigations and surveillance constitutes an alternative viewpoint to evaluate results of wastewater analysis."

The study's findings suggest that for some drugs, the wastewater-based epidemiology can be an effective tool to help law enforcement determine the market share that criminal elements control within the local drug market.

Journal Reference Been, F. et al. Analysis of illicit drugs in wastewater – Is there an added value for law enforcement? Forensic Science International, Volume 266 , 215 - 221; DOI: https://dx.doi.org/10.1016/j.forsciint.2016.05.032