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Are there traces of medicines in drinking water?

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Not only do we need to worry about water laced with microplastics, now there is the added concern of medicine contaminated water.

Asked by: Esther Owen-Ward


Yes, and it’s a growing cause for concern. In the early 2000s, a nationwide study by the US Geological Survey found that 80 per cent of streams in the US carried traces of pharmaceuticals, ranging from antibiotics and contraceptives to painkillers and antidepressants. These ‘active pharmaceutical ingredients’ (APIs) have since been found in the water supply of many countries, including the UK. Some get there simply by being excreted by patients; others after being flushed down toilets unused; others enter the water supply during the manufacturing process.

At first, the concentrations of the ingredients were thought to be too low to worry about. But studies have since found much higher concentrations in water supplies in cities around the world, raising the risk of effects on both aquatic life and humans.

Antidepressants, for example, have been found in the brains of fish downstream from sewage treatment plants, with some of these chemicals affecting their behaviour, making them less cautious. Researchers in the UK have also found fish with both male and female characteristics in almost 90 per cent of the river sites they’ve surveyed. The cause has been traced to compounds found in contraceptives. This discovery has, in turn, led to suspicions that similar contamination may be playing a role in the decades-long decline in human sperm counts that has been recorded by researchers in many countries.

Definitive proof of the effects of these APIs may never emerge: there are simply too many potential culprits and pathways via which they could cause harm. While the concentrations are sometimes thousands of times lower than those in a single pill, the effect of low-level exposure over years or even decades is unknown.

Given the potential risks, however, government agencies are already taking action. The European Commission is finalising a strategy for addressing the problem. Meanwhile, the US Food and Drug Administration has issued guidance to patients, warning of the need to dispose of unwanted drugs responsibly by following any instructions on the label, or by putting the drugs in the bin in a sealed bag.

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Robert is a science writer and visiting professor of science at Aston University.


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