Too much medicine residue is ending up in Dutch lakes and rivers and some present a real risk to the aquatic environment, the public health institute RIVM said on Friday.

RIVM researchers looked at five over-the-counter painkillers and concluded that three in particular – diclofenac, ibuprofen and naproxen – present a risk. In particular, in half the locations investigated, the amount of diclofenac exceeded proposed European limits, the RIVM said.

This is because diclofenac is often applied to the skin as a gel which is then washed away when showering or doing the laundry.

“This means it is important to inform doctors and consumers and, whenever possible, to choose the most environment-friendly painkiller,” the RIVM said.

The impact on surface water from paracetamol and aspirin is less significant than for the other three painkillers, the RIVM said.

Last September, Brabant water board De Bommel said festival organisers should have to clean traces of drugs from waste water before pumping it into the sewers. 

Removing traces of ecstasy, cocaine and other drugs from the water is expensive and festivals themselves should have to pick up the bill, water board chief Bas Peeters said the Eindhovens Dagblad. “You can’t explain it to taxpayers,” he told the paper.