It’s no secret that the global explosion in illegal drug use is pushing up crime rates, leaving a devastating trail of health issues and playing havoc with workplace productivity around the world.
What’s less well known is the impact that illegal drugs are having on the environment and how we can mitigate it.
UniSA researchers are hoping to shed some light on the ecological damage by analysing the increasing amounts of wastewater-borne drugs entering the environment.
An interdisciplinary and cross-divisional team led by Professor Christopher Saint, Dean of Research and Innovation in the Division of Information Technology, Engineering and the Environment (ITEE), has been tracking the types and concentrations of illegal drugs found in water sources worldwide.
“We know that the use of cocaine, cannabis, amphetamines, ecstasy, heroin and other opioids has increased notably in recent decades,” Prof Saint says in a paper published in Water Research this month.
“It is estimated that at least 250 million people aged between 15-64 years used an illegal drug in the past 12 months and this number is expected to increase if recent trends continue,” he says.
Conventional treatment processes can remove some of these compounds from water sources but it is not an exact science and traces inevitably remain.
Previous research shows that drug use differs from one region to another. Cannabis is the most popular drug in Africa, Australia and the Pacific, while cocaine is more prevalent in South America. Similarly, opioids are the drug of choice in Europe and Asia.
Reports also suggest that illegal drug use per head of population in Australia is higher in remote areas than in cities.
“In general, the levels of illegal drugs measured in wastewater effluents is lower than in raw sewage, which proves that most compounds are capable of being removed in treatment processing,” Prof Saint says.
“However, it is common practice in many countries – particularly throughout Europe and the US – to discharge treated effluent into nearby rivers, and, inevitably, this is having an impact on our ecological systems.”
A 2005 study assessing levels of cocaine in Italy’s largest river (the Po), found that the river carried approximately four kilograms of the fine, white crystal powder every day. Even higher concentrations were found in Belgium.
Similarly, cocaine concentrations were also recorded in the UK’s Taff and Ely rivers and in Spain.
Opioid pharmaceuticals such as codeine have also been detected in surface waters at various locations across the world.
“Even though surface water opioid concentrations are in the low range, the possible effects of these drugs on humans and aquatic biota remains largely unknown and should not be ignored,” Prof Saint says.
“Unfortunately, there are almost no studies on the effects of these compounds on freshwater and marine species.”
Studies in 2012 and 2015 looking at the potential toxic impact of wastewater-borne drugs such as cocaine and amphetamines found significant DNA and enzyme damage to aquatic organisms.
The residual amounts of drugs detected in water sources varies around the world, depending on the technology used. Activated sludge treatment, for example, is far more efficient than trickling filters for removing illegal drugs.
However, far more research is needed to identify the most effective removal pathways to protect the environment, the authors say.
“There is relatively little data on the most efficient methods of removing illegal drugs from our water sources and this is an important gap in our knowledge which should not be neglected,” Prof Saint says.
Joining Prof Saint in this UniSA research published in Water Research are PhD student Meena Yadav, Dr Michael Short and Dr Rupak Aryal from the School of Natural and Built Environments; Dr Ben van den Akker from SA Water Corporation and Dr Cobus Gerber from the School of Pharmacy and Medical Sciences.