How much cocaine is going up Dublin's nose? The answer lies in the output from the city's wastewater treatment plants - at least according to research done at Dublin City University by Brett Paull and colleagues. The researchers have estimated the levels of consumption of substances such as cocaine and morphine by measuring their concentrations, and the concentrations of their metabolites, in effluent and surface water.¹

'There are currently very few ways to non-invasively assess community consumption of illicit drugs,' said Paull. 'Social survey data, although useful, is often subject to sampling bias, whereas environmental forensic approaches such as this, when subject to stringent quality assurance and controls, could provide a more accurate assessment.' 

Previously, Paull's team surveyed drug contamination on euro banknotes in Dublin.² 'However, as an indicator of societal abuse, such samples provide only limited information,' said Paull. But water treatment plants accurately record the volume of water flow and serve a known number of people, allowing total consumption to be estimated.

Using samples taken from the water plant that serves 1.7 million people within the Dublin metropolitan area, the researchers calculated that more than 220 grams of cocaine flowed through the plant per day. Taking into account the way cocaine is metabolised in the body, this equates to the total consumption of more than 2200 grams of cocaine. The researchers estimate that this is equivalent to a consumption level of about 1.4 grams per 1000 people per day.

'The problem of cocaine consumption is not wholly confined to the capital city,' said Paull. Similar measurements on wastewater treatment plants that serve small towns just outside Dublin revealed consumption levels at about one fifth that of the metropolitan area. 

The researchers believe that their method could be used for the routine monitoring of cocaine consumption within a community, revealing any usage trends, such as increases during weekends and public holidays.

Colin Batchelor