The amount of medicine residue in our river water has been a point of concern for a while. Researcher Daniel João Duarte: “The tricky part about medicine residue in water is that we simply need medicine. We get ill and take medicine which our body then excretes, often unchanged. This goes through the sewage system to end up at wastewater treatment plants, after which the water enters the river. But they cannot remove all the residue.” Little is known about the consequences of individual medicine residue in water, let alone complex mixtures of contaminants. “But we do use this water. We swim in it, eat fish from it. And we don’t know enough about what this residue does to us.”
Polluted fish
Duarte and colleagues investigated the risks of pharmaceutical pollution for humans and the environment. “In our research on the Vecht river, we saw that under normal weather circumstances 68% of the water contained medicine residue concentrations higher than the environmental safe limits that are there to protect life under water. The risks for people who swim and fish there, were limited. However, in a typical dry, hot summer 98% of the water in the river exceeded the safe limits for life under water. In extreme situations, also the health risk for people increased, especially if polluted fish were to be eaten.” Residue of the medicines ethinylestradiol (contraceptive pill), carbamazepine (epilepsy medicine) and diclofenac (painkiller/anti-inflammatory) appeared to pose the greatest risk to water animals.
Resistance
Duarte also looked at the antibiotic resistance of microbes in sewage water, in both a global and local scale. Globally, he saw that it is highly plausible that the rise in environmental antibiotic-resistant microbes is linked to pollutant antibiotics. ‘When researching locally, we observed that in Nijmegen, it strongly appears that waste water from hospitals plays a particularly major role in spreading this resistance.’
Added to this is that the Netherlands is unlucky, as the water in our rivers has travelled very far before flowing past us. This means that everything that happens and is discharged upstream heads our way. Duarte: “Rivers don’t care about borders. Different countries through which a river flows have different measures or ability to tackle pollution. The problem is that the water all ends up here in the Netherlands.” The researcher calls for better international regulations based on proactiveness and precaution with a One Health mindset. “But hospitals could also do more to ensure that their waste water is cleaner. Too little attention is currently paid to pharmaceutical pollution, while it is becoming a greater and greater problem.”