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Cocktail effects

Our urine is full of medicine – soon we will be drinking medicine residues

More and more medicine residues are contaminating our drinking water. Most of these are flushed with the urine down the toilet when we take medication, and this increases the risk of cocktail effects in our water. Therefore, there is a need for new approaches to quality assurance of the consumers’ drinking water, SDU expert emphasises.

By Birgitte Svennevig, , 12/16/2021

Whether from a tap or a bottle, the water we drink will never get completely clean. It will always contain an abundance of different substances, and more and more of them come from, for example, drugs and pesticides.

- Today, we actually drink pesticide residues when we drink water. They are below the limit values, but they are in the water nonetheless. We are also finding more and more medicine residues, and in the near future we will probably also find medicine residues in all of our drinking water, says Frants Roager Lauritsen, who is a professor and an expert in the analysis and formation of the by-products that occur in connection with water purification.

This applies to both the Danish tap water that is pumped up from the underground and the purified surface water that almost all other countries supply themselves with.

Down in the big soup

The big question, then, is: Does it matter, as long as the substances stay below the limit values?

- Nobody knows. However, we do know that the active substances in, say, pesticide and medicine residues can interact with each other, and the purification process can break them down into other chemical compounds that may end up being more troubling than the original drug or pesticide, Frants Roager Lauritsen says.

This means there are almost infinitely many combination possibilities for new compounds and by-products that can occur in the drinking water.

The active substances in, say, pesticide and medicine residues can interact with each other, and the purification process can break them down into other chemical compounds that may end up being more troubling than the original drug or pesticide

Frants Roager Lauritsen, professor

Against this background, Frants Roager Lauritsen believes that it is necessary to streamline the methods we use today to characterise the efficiency of a water purification plant.

- There is so much happening and so fast with our drinking water that we need to be able to get quick answers on whether the water is toxic – and whether our purification methods work, he says and continues:

- With the traditional approach, where a water supply ensures the quality of drinking water based on analyses and screenings for known pollutants, it can easily take years before the presence of a new pollutant is discovered. After this, it may again take years before the toxicological effect of the new substance and the purification plant’s ability to remove the pollutant are clarified.

We need to look at integral wholes, not just individual substances

There is a need for new approaches to quality assurance of the consumers drinking water, Frants Roager Lauritsen emphasises:

- We need to adopt a number of methods that can quickly and broadly assess whether a given drinking water resource – for instance, a lake – poses a toxicological danger, he says and elaborates:

- If so, we must be able to determine whether an existing purification technology can eliminate the danger of toxic substances, and we must also be able to determine whether the purification creates any unwanted by-products – that is, if one harmful substance is merely transformed into others.

There is so much happening and so fast with our drinking water that we need to be able to get quick answers on whether the water is toxic – and whether our purification methods work

Frants Roager Lauritsen, professor

He himself is working on developing a portable reactor capable of monitoring chemical and biological processes as they occur. The reactor can tell within a short time whether it is possible to convert the harmful substances into harmless water and carbon dioxide when the water is disinfected, or whether the disinfection instead leads to the formation of harmful by-products.

Such a reactor would allow us to both monitor a water purification plant and, in terms of research, use the reactor to test and optimise completely new, advanced purification technologies.

While Frants Roager Lauritsen is working on developing the reactor for chemical characterisation of water purification processes, other researchers are working on developing methods for broad-spectrum characterisation of the toxicological danger of water.

Artificial intelligence can help

Together, the two methods can provide sufficient information for quality assurance of drinking water, even when new pollution hazards arise. And by connecting artificial intelligence and machine learning to the vast amounts of data collected through monitoring, the future may offer effective monitoring of our drinking water. 

- A computer can very quickly and accurately tell us whether the water is safe to drink or not – and what it takes to purify it, says Frants Roager Lauritsen. 

Where do the medicine residues come from?

The vast majority are flushed with the urine down the toilet by people taking medication. According to a report from DANVA, in Denmark the medical residues include antibiotics, antidepressants, hormones, anti-inflammatory drugs and medicines for cardiovascular diseases.

Read more about medical residues in the report from DANVA (only in Danish).

Meet the researcher

Frants Roager Lauritsen is a professor and, having served as Head of Department at the Department of Physics, Chemistry and Pharmacy for 9 years, has resumed his research into analysis of water purification processes and the formation of by-products that disinfection of water can entail.

Contact

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Editing was completed: 16.12.2021