Medicine residues are increasingly found in nature, particularly in rivers. But what actually happens when these remains are mixed with the water? Scientists are investigating the effects and consequences on all organisms in these waters.
High concentrations of antibiotics
Earlier this year, dangerously high concentrations of antibiotics were found in countless rivers, a study by the University of York revealed. The researchers discovered that the highest concentrations were found around wastewater treatment plants and dumps, where the substances leak into the water. And it does not only stay with antibiotics, but also medicines such as antidepressants, anti-inflammatory drugs, anti-fungal medication, medicines for diabetes, painkillers, antihistamines and anti-epileptics end up in the water.
The researchers found that the safety limits were most often exceeded in Asia and Africa. The highest concentrations of drug residues were found in rivers in Bangladesh, Kenya, Ghana, Pakistan and Nigeria. But also in Europe, North America and South America the rivers are far from healthy. The WWF recently published a report in which they state that a large part of the British rivers are not of good quality. The rivers appear to contain to a large extent illegal drugs, pesticides and chemicals. And these also end up in the animals that live in these waters. Researchers found cocaine and other illegal drugs such as ketamine, pesticides and pharmaceutical products in small freshwater shrimp.
Consequences of polluted rivers
What are the consequences of the highly polluted rivers? Many antibiotics appear to be very toxic to blue algae, because these algae contain the receptor that the antibiotic targets. There are also studies that suggest that these molecules can influence the germination and growth of plants. Researchers at Wageningen University published a study at the beginning of this year in which they charted the risks of the antibiotic ciprofloxacin and carbamazepine. For the two drugs, the environmental risks in 2015 were ten to twenty times higher than in 1995.
Rik Oldenkamp , lead author of the study, says:“The concentrations of the antibiotic are harmful to the bacteria in the water, which in turn play an important role in all kinds of food cycles. In addition, antibiotics can also have a negative impact on the effectiveness of bacteria colonies used in water treatment.”
Effects on fish
Researchers discovered that even a low dose of certain medicines, or concentrations that are permitted in water, can still have consequences over the longer term. Nothing is yet known about the effects on humans, but we do know that drug residues that end up in the water change the behavior of fish. The antidepressant serotonin reduces the territorial behavior of coral fish. It also has a visible effect on the motor skills and aggression of Siamese fighting fish. Benzodiazepines, which are prescribed for anxiety disorders in humans, make fish more aggressive. The active ingredient in the contraceptive pill can affect the sexual characteristics of male fish. Especially for antidepressants, there is increasing evidence that – even permitted concentrations – affect the behavior of fish, invertebrates and birds and this can affect the health of entire populations.
How are we going to solve this?
According to researcher Alistair Boxall, it is important that we place the polluted rivers higher on the agenda. “If we do nothing, our rivers will continue to pollute and the global problem will become bigger and bigger, with all its consequences for our ecosystem.” According to him, the solution lies in stricter regulations and the cleaning of already contaminated locations. Investments will also have to be made in better wastewater treatment plants and the development of more environmentally friendly medicines.