Did you know that substances found in medicines, cosmetics, cleaning products, and pesticides could be contaminating Brazil’s rivers? Among them, compounds known as emerging contaminants (ECs) are not subject to monitoring regulations and can cause serious harm to aquatic life, especially to species that are already threatened with extinction.
These pollutants enter rivers mainly through the discharge of domestic and industrial sewage, which is often untreated. Although invisible to the naked eye, they are far from harmless. Studies use a tool called the Risk Quotient (RQ) to measure how dangerous these substances are to organisms. When the RQ value exceeds 1, it triggers an alert, indicating a real risk to biodiversity.
Brazil's northern region holds the largest share of the country's freshwater resources. Despite this, there are few studies on the impacts of these contaminants in the area. This is concerning: even though the region is less populated, it is already showing signs of pollution, putting animals such as fish and amphibians at risk.
Figure 1. Dead fish in the Amarapari River. Available at: https://revistacenarium.com.br/no-ap-contaminacao-em-rio-deixa-cidade-ha-10-dias-sem-agua-e-provoca-morte-de-animais/
A study by researcher Felipe Branco from the Federal University of Pará (UFPA) analyzed data from three river basins in the Amazon region—the Northeast Western Atlantic, the Tocantins-Araguaia, and the Amazon. The result? More than 100 fish species and approximately 10 threatened amphibian species were identified in these areas, along with 12 hazardous substances with an RQ greater than 1.
Among the most commonly detected contaminants are pesticides, pharmaceuticals, hormones, and antibiotics. According to the study, the presence of these compounds is mainly linked to agricultural expansion and the lack of basic sanitation services, such as sewage collection and water treatment.
Figure 2 - Graph describing the endangered species in the different basins analyzed and the number of ECs found. Available at: https://revistabrasileirademeioambiente.com/index.php/RVBMA/article/view/942
But why does this matter? The effects of emerging contaminants are varied and alarming: they can cause reproductive problems, slow organism growth, disrupt hormonal systems, and even lead to the death of aquatic animals. An interesting fact: researchers have observed that even the heart rate of fish embryos can be altered, serving as an indicator of contamination.
And it doesn't stop there. As we consume large amounts of fish and seafood, these contaminants can reach our plates. Between 2007 and 2014, more than 25,000 cases of human poisoning were recorded in Brazil.
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References
BRANCO, F. O. L. ; CARDENAS, S. M. M. ; SERRAO, I. C. G. ; CUNHA, I. R. V. ; AMADO, LILIAN LUND ; KUTTER, V. V. T. . Contaminantes Emergentes na Bacias Hidrográficas Brasileiras e seus potencias efeitos em espécies ameaçadas de extinção. Revista Brasileira de Meio Ambiente, v. 9, p. 140-174, 2021.
