The hydrographic basin of the Piracicaba, Capivari and Jundiaí rivers — also called the PCJ basin — extends across 76 municipalities in the state of São Paulo and serves more than 5.8 million people. With a drainage area of more than 14 thousand kmtwo, its waters are highly demanded by agriculture, industry and population consumption. As a result, and in the context of the global climate crisis, the basin currently suffers from water scarcity.
But this is not the only or the biggest problem: the large group of rivers, streams and streams that make up the basin are also heavily contaminated by agricultural, industrial and domestic effluents.
The visible expressions of this pollution have already been the subject of several media reports. But there was a lack of an in-depth study that would identify the main contaminated areas and the nature of individual contaminants and mixtures of contaminants; to calculate its concentration, frequency and toxicity, and to point out its potential risks to humans and aquatic organisms.
This study was now carried out by researchers from Unicamp (State University of Campinas) and partners from other institutions in the country and abroad. The work was supported by Fapesp through three projects, and an article reporting the results was published in the journal Chemosphere.
“In addition to traditional contaminants, already well known and subject to legislation, we also found emerging contaminants, not yet legislated, which present toxicity under conditions of chronic exposure. Our research provided the first portrait of the occurrence of compounds from the PFAS group in rivers in the state of São Paulo”, says Cassiana Carolina Montagner, professor at the Unicamp Chemistry Institute and coordinator of the study.
PFAS are a group of thousands of synthetic, perfluoroalkylated chemical compounds used by industry in a wide variety of products with the aim of making them non-stick, waterproof and stain-resistant. The best known use occurs in non-stick utensils coated with Teflon.
A report from the United States Environmental Protection Agency (Usepa) lists several human health problems proven to be associated with exposure to PFAS. Among them, the increased risk of some types of cancer, including kidney, prostate and testicular.
“The occurrence of seven PFAS in different rivers in the state of São Paulo was reported for the first time in our study,” says Montagner.
But that is not all. “We also detected many other contaminants, making up a total of 45. The agricultural pesticides atrazine, carbendazim, tebuthiuron and 2,4-D were those with the highest frequency of detection, having been found in 100% of the samples collected”, he says.
“The same frequency, 100%, was also detected for caffeine and bisphenol A [BPA]taken to rivers by domestic sewage”, adds the researcher.
Here it is important to say that, although well tolerated by humans, caffeine can be quite harmful to aquatic biota, as Montagner highlights. Bisphenol A is an organic chemical substance, 2,2-bis(4-hydroxyphenyl) propane, used in the manufacture of high-performance polymers and coatings.
Plastics used in household appliances, computers, toys, disposable cutlery, baby bottles, food and drink can linings and epoxy resins contain BPA. It also appears as a component of malleable PVC in thermal papers, such as bank statements and payment receipts released by ATMs and card reading machines.
To assess the extent of the impacts caused by all these contaminants, it is necessary to consider that the region served by the PCJ basin is an important agricultural and industrial hub and also home to large cities.
The area accounts for 5.3% of the Brazilian GDP (Gross Domestic Product). Highlights are the production of sugar cane in the municipality of Piracicaba (SP), the textile industry in the municipality of Americana (SP) and the large population concentration in the municipality of Campinas (SP).
“In addition to being the main source of drinking water for the entire area, the PCJ basin provides water for irrigation, which does not receive any treatment before being used in agricultural fields. At the same time, the region is home to many small towns that release sewage almost in natura in rivers”, says Montagner.
The researcher emphasizes that emerging contaminants, such as pesticides, hormones, pharmaceuticals, industrial chemicals and PFAS, are being released into the PCJ basin, without current Brazilian legislation requiring their monitoring.
“In our study, we collected samples at 15 different points in the basin. And we evaluated the contaminants present considering three factors: concentration, frequency and toxicity. In addition to the high frequencies already mentioned, we obtained high risk quotients for the herbicides diuron and atrazine, in addition to the imidacloprid insecticide”, he says.
And he concludes: “In addition to old unresolved pollution problems, such as contamination by fecal coliforms, for example, there are new problems now caused by the presence of emerging contaminants, which are produced to guarantee the quality of modern life, but reach the environment due to poor management of solid waste and inefficient sanitation”, he says.
“Our study suggests that it is necessary to establish a comprehensive monitoring program to ensure the protection of aquatic life and human health,” he concludes.
Contacted by the report, Cetesb (Companhia Ambiental do Estado de São Paulo) reported in a note that measurements are currently made quarterly at 519 sampling points, of which 91 are distributed in the PCJ basin.
In addition to traditional parameters, such as organic matter, nutrients, coliforms and metals, Cetesb measures pesticides and some emerging compounds, quantified indirectly through two tests: one that measures estrogenic activity, for the detection of endocrine disrupting compounds. (which mimic female hormones, such as BPA); and another that measures the activity of glucocorticoids, to detect drugs from the anti-inflammatory class.
The text also states that pesticides (42 different active ingredients) have been measured by Cetesb since 2017, in stretches of rivers located in basins with predominantly agricultural land use.
“In the PCJ watershed, pesticides have been monitored since 2018 in the headwaters of the Corumbataí River […], municipality of Analândia, with around 65% of the basin area destined for agricultural use. The pesticides most frequently detected in this stretch of the Corumbataí river from 2018 to 2022 were the insecticide imidacloprid [bastante frequente também nas amostras analisadas na Unicamp] and the herbicide tebuthiuron [este encontrado em 100% das amostras do estudo]”, it says.
“Imidacloprid concentrations were frequently above the USEPA chronic ecotoxicity limit for aquatic invertebrates [Office of Pesticides Program, OPP]which is 10 ng/L [nanograma por litro]. During the same period, the pesticides 2,4 D and atrazine were not detected in this section. [ambos detectados em 100% das amostras analisadas na Unicamp]which are covered by quality standards for the protection of aquatic life.”
Finally, Cetesb informs that there are no legislated values for estrogenic activity and glucocorticoids. “The results of these two tests, obtained over the last five years in the PCJ river basin, indicated values, in both tests, considered low or of low relevance, based on studies already carried out and international experience.”
The article can be accessed here (in English).