Cocaine widely detected in some of NI's major lakes and rivers

Cocaine is widely present in the water of some of Northern Ireland's major lakes and rivers, a new study has found.

Scientists found the Class A drug, and its by-product, in 91% of almost 140 water samples collected in different locations from five waterways - the River Lagan, River Bush, Dundrum, Lough Neagh and Lough Erne.

Ketamine and amphetamine, two Class B drugs that are also used as pharmaceuticals, were also found as well as painkillers and antidepressants.

Dr Billy Hunter, the lead author of the study, said it highlighted that drugs of abuse were not "solely an urban problem; they are present right across Northern Ireland".

The research, conducted by the Agri-Food and Biosciences Institute (AFBI), in collaboration with Imperial College London, focused on raw water in rivers and lakes, not drinking water that comes from our taps.

While there is no risk to human or pet health from interacting with the water, the study does raise concern for ecosystem health and reflects the extent of drug use in Northern Ireland.

Dr Hunter told The State of Us podcast that while cocaine was detected in high levels in and around Belfast, mostly due to its population, he was surprised to find it was "broadly everywhere".

"One of the interesting things is actually the fact that it was showing up quite strongly in places like Lough Erne, which is maybe because it's a recreation hotspot."

He added that using future studies to monitor the water for drug levels will be important, with statistics showing that almost 46 million prescriptions were issued in Northern Ireland in 2024/25, external.

"The population's ageing, people need more healthcare and the healthcare system is in difficulty so you have people taking pain medication to manage conditions for much longer," he added.

While most substances pose low environmental risk, diclofenac, an anti-inflammatory drug, and caffeine were identified as presenting moderate to high risks.

The study also found that an antibiotic - trimethoprim, which is often used to treat urinary tract infections - may be contributing to an increased risk of drug resistance, especially around the River Lagan in Belfast.

The study looked at 137 water samples collected from 50 locations from Lough Neagh, Lough Erne, Dundrum, River Lagan and River Bush between December 2022 and February 2024.

Cocaine, and its by-product benzoylecgonine, which can be detected in urine after using the drug, were found in 91% of samples.

Scientists found 21 compounds in total, with tramadol - a strong opioid painkiller - present in 91% of samples, caffeine found in 80% and the antidepressant venlafaxine in 76%.

While Northern Ireland's waters were found to be less heavily contaminated overall compared to other regions of the UK and Ireland, the detection of pharmaceuticals, personal care products and illicit drugs raises concerns for ecosystem health and human exposure.

The study also reflects other evidence indicating the regular use of cocaine in Northern Ireland.

In the year up to the end of September 2025, the Police Service of Northern Ireland (PSNI) recorded more than 7,000 drug seizure incidents - cocaine was the second most commonly seized drug, after cannabis, with 1,353 seizures.

Meanwhile of the 3,974 people recorded on Northern Ireland's Substance Misuse Database in 2023/24, cocaine was the most commonly used drug with more than half of those who use drugs reporting taking it.

The study also detected ingredients and additives from personal care products such as cosmetics, toothpaste, deodorants and washing detergents.

In terms of the risk to people and their pets, Dr Hunter said it was minimal right now though the presence of drugs in lakes and rivers could add to the cumulative detrimental effect on marine ecosystems.

"There is some evidence, particularly in England, of drugs having an effect on the environment. Some studies have shown that antidepressants are having an effect on shrimp in rivers and changing their behaviours, changing their dynamics within the ecosystem."

Meanwhile, he said it was caffeine that posed "the greatest environmental risk in Northern Ireland".

"If you think about what caffeine does, it peps you up, it raise your metabolism a little bit, it's a stimulant.

"If it's doing that to animals in the environment, they're going to be hungrier and more alert, their interactions within the food web are going to change because of that."

Dr Hunter also said the possibility of developing antibiotic resistance in the River Lagan area was "definitely" a concern.

"The risks around antimicrobial resistance are quite pronounced. That's a game where you come back to human health because if bugs are able to pass on antibiotic resistance in the environment then those bugs potentially bring infection back into contact with humans."

Prof Leon Barron, from Imperial College London, said it was encouraging to see water contamination in Northern Ireland was less compared to similar studies in other parts of the UK.

However, he added, "this was no reason to become complacent".

"There are so many more chemical types used every day, and we should consider expanding our scope to include them. Importantly, we have demonstrated that we can use these powerful tests quickly and at large scale to catch pollution early."