Too many medicine residues end up in surface water. RIVM has investigated the impact on surface water resulting from five painkillers that are also available without a prescription. The research shows that diclofenac, ibuprofen and naproxen present a risk to the aquatic environment. In half of the locations investigated, the amount of diclofenac exceeded the proposed European limit value. This can impact the aquatic environment. It is therefore important to inform doctors and consumers and, whenever possible, to choose the most environmentally friendly painkiller.

Research into the impact of five over-the-counter painkillers on water

Medicine residues in water can be harmful to aquatic animals. For five over-the-counter painkillers, RIVM determined how much of the active substance enters the surface water through the sewer system. It then determined the associated risks by comparing this information to environmental risk limits. It also looked at how using a different painkiller would affect the quality of surface water.

The painkillers investigated were paracetamol, aspirin, naproxen, ibuprofen and diclofenac. Especially for diclofenac, the amount ending up in surface water is often too high. This is because this painkiller is often applied to the skin as a gel. Most of the gel is then washed away when showering or doing the laundry. Ibuprofen and naproxen also present a risk to surface water. The impact on surface water from paracetamol and aspirin is less significant.

Conscious choices and appropriate use

It should be stressed that painkillers are only used when necessary. This is referred to as appropriate use. Additionally, paracetamol and aspirin have less impact on water quality than diclofenac, naproxen and ibuprofen.

When choosing a painkiller, the main considerations are effectiveness and patient safety. Further consideration should be given on how to include environmental effects of painkillers in the different treatment guidelines. This could allow healthcare professionals to make an informed choice, also taking impact on water into account.

Other stakeholders should be consulted to determine how consumers can be informed in the best way, so they can choose the painkiller that is least harmful to the environment.

Objective: reducing medicine residues in surface water

Water quality is under pressure in the Netherlands. At the same time, our medicine use continues to increase. Patient use makes up the most important route for medicine residues to end up in surface water – through the toilet, rinsing of the body or doing the laundry.

Sewage treatment is not very effective at removing medicine residues from wastewater. This leads to risks to the aquatic environment and complicates drinking water production. That is why it is important to prevent medicine residues from ending up in surface water.

The Dutch Chain Approach on Pharmaceuticals in Water (Ketenaanpak Medicijnresten uit Water) focuses on reducing the quantities of medicine residues that enter the aquatic environment. This approach covers the entire chain, from the development, production, and use of medicines, to water treatment.