A team consisting of scientists from the National Scientific and Technical Research Council (Conicet) and the National University of La Plata published a unique study in the region on the presence of drugs in watercourses. Its peculiarity lies not only in the size of the areas studied, but also in the conclusions that the specialists came to: they found seven tributaries that cross the river Buenos Aires Metropolitan Area (AMBA) Strikingly high concentrations of active ingredients.
The most frequently found substances were Paracetamol, ibuprofen, the antiepileptic drug carbamazepine and metformina drug primarily used to treat type 2 diabetes and insulin resistance. They also found high doses of Sildenafil, better known as Viagra, and Clonazepamalong with a dozen medications.
Daniela Perez and Pedro Carriquiribordetwo of the authors of the study published in the American scientific journal Environmental toxicology and chemistrypublished by the University of Oxford, confirm that although drugs have been detected in rivers and streams in many countries, the Argentine case stands out for the high concentrations found, plus the fact that, as they were able to verify, To a certain extent, these substances bypass the wastewater treatment plants.
“What we observe is that the greater the human density in an area, the more pharmacological substances are present in the water, regardless of whether there are primary treatment plants. Conventional primary treatment plants are not able to eliminate 100% of drugs. Therefore, these substances end up in the receiving waters, in this case the Río de la Plata,” explains Carriquiriborde, who has a doctorate in natural sciences, Pedro, researcher at Conicet and specialist in Environment Pollution and Ecotoxicology.
The study authors emphasize that the main source of drug contamination of water is both sanitary sewage and household waste that ends up in streams and rivers. “We wanted to show that the problem is mainly urbanizations without services or without adequate services. In fact, one of the places where we found the highest concentration of drugs was in Reconquista, at a sampling point in front of the Ceamse, so we assume that there is some involvement of landfills in this type of contamination. A point of high drug contamination that surprised us a lot was the Maldonado stream, which crosses several settlements where people use their wastewater often thrown directly into the city.” Stream,” explains Carriquiriborde
The Environmental Research Center (CIM) team, which includes Carriquiriborde and Pérez, the study’s lead author, has been studying the presence of drugs in the environment for 10 years. In 2022, the group of scientists that compose it participated in an international comparative project on drug contamination in which a hundred countries took part.
Each country provided drug concentration figures for one of its urban tributaries. In the Argentine case, the choice fell on Riachuelo. In the comparative study, the country ranked 15th among countries with the highest concentration of drugs in surface waters. In the ranking, Pakistan came first, followed by Bolivia, Ethiopia, India, Tunisia, the Democratic Republic of Congo and Armenia.
With this project, CIM scientists wanted to better understand how drugs behave and what impact they have on the waterways that cross the Buenos Aires metropolitan area.
For their latest study, they sampled seven tributaries of the La Plata River that run parallel throughout the area, starting in rural areas and passing through various population centers along their route. The Luján, Reconquista and Matanza-Riachuelo rivers were chosen; the Del Gato, Maldonado and El Pescado streams, whose basins cross the cities of La Plata, Berisso and Ensenada, and the Espinillo stream in the Magdalena district.
The researchers They took samples at different heights in the pools analyzed. They concluded that as the population increases, “the number and concentration of this type of chemical substance also increases.” While they found an average of two to three drugs in rural waterways, samples taken from urban waterways found residues of virtually all of the 16 drugs they were looking for.
What particularly struck the researchers was the high presence of Paracetamol. “It is the drug that has the highest average concentration in the water tested. This has to do with the consumption of the population. In Argentina, for example, not as much fluoxetine, an antidepressant, is found in the water as in Canada and the United States, but more sertraline, another type of antidepressant. Here, for example, clonazepam is more common than in other countries of the world, where the consumption of this drug may have already been replaced by another,” he explains. Carriquiriborde.
The study was conducted in two periods in 2022, winter and summer. From this, the researchers were able to conclude that in addition to cultural factors, there are also other factors such as climate and season that influence drug consumption. An example is the presence of Viagra in water, indicated for erectile dysfunction, which, as described in their study, had a much greater concentration and presence in watercourses during summer sampling, which could be associated with an increase in sexual activity at that time.
When asked about the impact of the concentration of drugs in water on human health, the researchers emphasize that it is not possible to draw conclusions in this regard with the information obtained, since they did not analyze purified water. “Basically, I would assume that the impact is zero,” emphasizes Carriquiriborde.
However, the specialist believes that drug contamination does have an impact on the health of the aquatic fauna and flora of the tributaries studied, one of the topics his team is currently investigating. “There are places where we sample, like the last points of the Reconquista and the Riachuelo, where there are almost no plants or animals. They look like dead canals fish, when in similar rivers there are up to 24 species,” he elaborates.
When asked about possible solutions to this type of pollution, the expert says: “The return of expired medicines could be encouraged instead of throwing them on the roof. It would also be good to carry out infrastructure works on the sewerage system and bring sewage waste to treatment beaches with technologies that can eliminate medicines,” he claims.
The CIM team hopes that the data obtained from its report will serve as a starting point so that relevant authorities and government districts can know the status of metropolitan streams and rivers and act accordingly.
“It’s about understanding that what we take in and throw away does not end its cycle in the toilet or the trash can, but goes somewhere, and usually it is water or land, and that is something that affects the environment and therefore all living things,” says Pérez.
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