A less visible type of pollution has been worryingly accumulating in rivers and lakes around the world: molecules that humans use for pharmaceutical or recreational purposes, from antibiotics and anti-inflammatories to the nicotine in cigarettes.
The first worldwide mapping of the problem, assembled by a team that includes Brazilian scientists, indicates that the risks posed by these pollutants are particularly high in places where the water and sewage network is already precarious for other reasons.
The presence of these substances in natural environments has been studied more and more intensively in recent years and, although many of their effects are still not well understood, there are already indications that they can affect the life cycle and health of fish, amphibians, waterfowl and microorganisms.
“These are biologically active molecules, that is, designed to interact with our organism in different metabolic pathways. Some of them may be present in other organisms, both aquatic and terrestrial, and there the concern increases”, says Maria Tereza Pepe Razzolini, professor from the Faculty of Public Health and co-author of the survey.
The research, which has just appeared in the scientific journal PNAS, was coordinated by John Wilkinson, from the University of York, in the United Kingdom, and took into account samples from 1,052 different locations, spread across 104 countries.
The Brazilian samples came from Manaus, Americana (São Paulo countryside) and the Pitimbu River, in the neighborhood of Natal (RN), says Jean Leite Tavares, from the Federal Institute of Education, Science and Technology of Rio Grande do Norte, who also signs the study.
The researchers assembled a list of 61 molecules, made up mainly of pharmaceutical products, but which also includes some recreational or food use, such as caffeine and nicotine.
In analyses, they found that only two sites — a Yanomami village in Venezuela and Iceland — have no traces of either of these substances. On the other hand, in just over a quarter of the rivers sampled, the concentration of at least one of the substances was above that recommended as safe for aquatic living beings.
The problem is most acute near metropolises in developing countries classified as lower-middle-income. The champions on the list are rivers near Lahore, Pakistan; La Paz, Bolivia; and Addis Ababa, Ethiopia.
According to Razzolini, these countries suffer more acutely from this type of pollution because, at the same time, they have relatively easy access to the most commonly used medicines, but they do not have a good basic sanitation and sewage treatment structure.
Urban areas in Brazil tend to be more or less in the middle of the list — not a very comfortable position. “This does not happen with Manaus, where the concentration is low because of the great flow of the Amazon”, points out Tavares.
“The situation in Americana is also better because of the basic sanitation infrastructure in the state of São Paulo. Here in Rio Grande do Norte, which was among the 60% of places with the most presence of drugs in the water, this infrastructure is weaker and the flow of the river is also much smaller”, he explains.
Among the drugs detected in rivers on all continents are, in addition to caffeine and nicotine, analgesics, drugs for heart disease, antidepressants, diabetes drugs, anti-inflammatories and antibiotics.
Many of them can have dangerous effects on other species. Those that affect the human nervous system can change the behavior of animals, for example, while antibiotics can end up leading to the selection of bacteria resistant to them, a problem that already worries hospitals around the world.
There is also concern about endocrine effects, which can even alter the sexual development of fish and amphibians. All this can have negative consequences for the health of those environments, such as water quality, and also affect the people who consume these animals.
In addition to investing in sewage treatment, preferably with more advanced techniques, the problem can be minimized with measures such as the restoration of riparian vegetation, which protects river banks and helps in water purification.
In addition, says Tavares, in 2020 Brazil created legislation that favors the reverse logistics of pharmaceuticals. That is, expired drugs, instead of being simply discarded, could return to the manufacturer using pharmacies as intermediaries.
“The question is how to implement this, which is still not clear in terms of costs and responsibilities, but it is a path”, he points out.
Chad-98Weaver, a distinguished author at NewsBulletin247, excels in the craft of article writing. With a keen eye for detail and a penchant for storytelling, Chad delivers informative and engaging content that resonates with readers across various subjects. His contributions are a testament to his dedication and expertise in the field of journalism.
