A recent study showed the presence of more than 52 types of active pharmaceutical ingredients in the river Danube, 32 of which even reach the drinking water of Budapest, according to the Víz, Gáz, Fűtéstechnika (Water, Gas, Heating Technology) and Hűtő, Klíma, Légtechnika (Refrigerator, Air-Conditioning) journal.
In and around Budapest, two large waterworks supply roughly two million people with drinking water that is purified by coastal filtration, which means the water is purified through the Pleistocene sand and gravel layer. The active pharmaceutical ingredients enter the Danube through human metabolism and medicines flushed in the toilet.
Hungarian researchers were curious about how effective the coastal filtration is against the pharmaceuticals that enter the Danube and through this, the drinking water system of Budapest. The study presenting their results was published in the Environment Pollution journal.
Researchers took a total of 107 samples from the Danube in a 100-kilometer-long section, and from nearly a hundred more samples from surrounding wells. Then they examined the frequency, concentration, and the effectiveness of the filtration of certain active substances found in the samples.
Of the 111 active ingredients the researchers sought, 52 were found in the waters of the Danube, and at least 15 in each sample. Ten drugs occurred with a frequency of at least 80%. The most common was bisoprolol (found in 107 samples, 100% frequency, an average of 3.80 ng/liter) a drug used to treat cardiovascular disease. Metoprolol was also found in almost all of the samples (105 of them, 98.1% frequency, an average of 11.4 ng/liter). Estrogen was found in 42% of the samples (this is often released into the water from female contraceptives). No residues of antibiotics were found, but this may have been because the test was not suitable for this.
Coastal filtration showed an efficiency of 95%, which means that 32 of the 52 active substances found in the Danube enter drinking water. However, they found a low filtration efficiency in the case of carbamazepine, lidocaine, tramadol, and lamotrigine. Carbamazepine was present in at least 90% of the Danube and drinking water samples, and its concentration did not decrease by filtration.
It was also observed that there is no correlation between the concentrations measured in the two sources. The filtration efficiency of each well is random, depending on the chemical and other characteristics of the natural filter layer. Although the concentration may not seem high at first glance, the active ingredients can easily cause health damage. That is why the European Union wrote a list of substances that pose a significant risk to the environment in 2001, which has already been updated twice and now contains 33 substances or groups of substances.
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