‘Medicines are making our rivers sick’: Pharmaceutical pollution likely linked to decline of freshwater life, warns report

High levels of painkillers, anti-inflammatories and antidepressants in UK waterways are likely to be contributing to the decline of freshwater life, a conservation charity has warned in a new analysis of scientific literature.

Gammarus Freshwater shrimp. Image: John Mason. Gammarus Freshwater shrimp. Image: John Mason.

Conservation charity Buglife has published a new report which highlights that the presence of common medical drugs in UK waterways is likely to be affecting the reproduction, behaviour and development of freshwater invertebrates such as snail, shrimp and mussels.

Wastewater treatment works (WWTWs) are a major source of the pharmaceutical contamination, according to Buglife, with concentrations for the 14 drugs examined exceeding predicted no effect concentration (PNEC) levels in discharges between 35% to 94% of the time.

The charity also notes that septic tanks represent “a large diffuse source of pollutants” but that unlike WWTWs they are “largely unmonitored and difficult to manage”.

READ MORE: Medicinal drugs have polluted Scottish waterways more than 2,300 times

While Buglife says few studies have measured the effects of pharmaceuticals at “environmentally relevant concentrations” or conducted long-term studies, several substances are known to have the potential to impact invertebrates in the environment.

“The most observed effect of pharmaceuticals in invertebrates are alterations in reproduction and growth, with some researchers suggesting peaks in effect at low concentrations for some substances,” reads the report. 

It adds that pharmaceuticals interact with each other and other chemicals in such a way that produces “toxic cocktails that are more harmful than single substances”. For example, the drug diclofenac breaks down into chemicals that are “six times more toxic to algae than diclofenac itself” according to the report. 

“Because of how long these chemicals have gone unchecked we do not know how much damage they are causing and how long they remain in the environment,” it says. 

The drugs of most concern due to their impact on invertebrates include ibuprofen, found in Scotland to have “high-risk quotients for 19 of 20 Scottish WWTWs in downstream waters”, and according to the Buglife report has been recorded to occur at concentrations that impact invertebrates. 

The report also says that antidepressants fluoxetine and venlafaxine, and the antiepileptic carbamazepine have also been found to regularly occur in the environment at concentrations that may harm invertebrates.

“Freshwaters are haemorrhaging biological diversity faster than any other ecosystem on earth. Whilst medicines are essential to human health, their residues are making our rivers sick, with commonplace drugs present in concentrations that are harmful to freshwater invertebrates,” said Craig Macadam, conservation director, Buglife.

He added that the UK needs “a prescription for our rivers” that improves WWTWs, and which “properly evaluates the risks, and reduces the opportunities for the most harmful substances to enter the water environment".