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CHEMISTRY

Emerging contamination

Caffeine found in treated water indicates the presence of other harmful substances

Shortages and the risk of rationing are not the only problems that some Brazilians are facing when it comes to water. The growth of cities and their dense populations, combined with poor sanitation and new consumption habits, have contributed to the release of hundreds of substances resulting from human activities into water sources (rivers, lakes and underground deposits). These substances are known as emerging contaminants (EC). A recent survey, conducted at the University of Campinas (Unicamp), has contributed to determining the scale of the problem by studying the presence of caffeine in water. This substance serves as an indicator of the presence of other substances in public water supply systems.

Wilson de Figueiredo Jardim, a researcher and deputy coordinator of the National Institute of Science and Advanced Analytical Technologies (INCTAA) and an associate professor at Unicamp’s Chemistry Institute, is one of the authors of the book Cafeína em águas de abastecimento público no Brasil (Caffeine in public water supplies in Brazil), published in 2014. He says that the term “emerging contaminant” is wide-ranging and may include more than a thousand compounds. Besides not being covered by current legislation, these substances have in common the fact that they are found in various types of environments, which increases human exposure to them. “We’re talking about prescription and non-prescription drugs, illegal drugs, nanomaterials, personal hygiene products, insect repellents, sunscreens, water chlorination and ozonation products, microorganisms, and natural and synthetic hormones, in addition to others,” he says. “The list includes new and old substances that are part of our daily routines.”

In light of this, the United Nations Environment Program (UNEP) has declared the problem serious enough to merit the attention of governments to identify EC sources, routes and receptors in nature. According to Jardim, there is already ample evidence that wild animals, especially fish, reptiles and amphibians living in places with large domestic sewage concentrations, have problems with feminization, infertility and inter-sexuality. This is because, besides the natural hormones excreted in sewage, there are considerable amounts of similar synthetic hormones coming mainly from birth control pills and hormone replacement therapy. “Furthermore, numerous molecules such as bisphenol A and various chlorinated pesticides, among others, may confuse our endocrine systems,” he says.

In significant amounts
The problem is getting worse because, according to Jardim, it is not feasible to establish legislation for hundreds of compounds, thus posing a huge challenge for public policy. Therefore, the scientific community is working on identifying possible indicator substances, that is, a compound that can point out the risk of exposure to certain classes of products. That’s where caffeine comes in. It is an excellent indicator, because of its association with compounds of estrogenic activity that can alter the hormonal metabolism of the human body.

Jardim believes that the caffeine found in water sources is mostly derived from sewage, because it is the most widely consumed beverage in the world after water. “High concentrations in the source indicate that it receives significant amounts of domestic sewage,” he says. “Effective disinfection of the water supply removes evidence of fecal contamination, but caffeine is a resilient compound and therefore leaves a chemical fingerprint. We can say that where caffeine is found, although its concentrations may not be toxic, there will be a variety of other compounds that are not being monitored, but may have some impact on human health.”

In the study he coordinated, Jardim collected 100 samples of treated water at 61 points spread over 22 capitals (five in Brasilia; four in São Paulo, Rio de Janeiro, Fortaleza and Recife; three in Porto Alegre, Curitiba, Belo Horizonte, Vitória, Cuiabá, Manaus, Belém and Salvador; two in Goiânia, Campo Grande, Porto Velho, Natal, São Luís, João Pessoa and Teresina; and one in Florianópolis and Palmas). Two campaigns to collect samples were conducted between July and September 2011 and 2012. Porto Velho and Palmas had samples collected only in the first campaign, while Campo Grande, Manaus, Belém, São Luís, Teresina and Salvador had samples collected only in the second. The other capitals were studied in two sampling periods; in São Paulo and Rio de Janeiro the collection points varied between the first and the second campaigns.

Serious situation
According to Jardim, the results to some extent showed what was expected. “But we had no idea how serious the lack of sanitation and its consequences were both in the quality of the water sources and the water distributed to the population,” he says. “First, we determined that surface water sources (rivers and lakes) have caffeine concentrations on the order of 1,000 to 10,000 times higher than those found in Europe, the United States, Canada and Japan. Even groundwater had measurable concentrations of caffeine.” Nationally, we found that the conditions were not very different from those measured in the state of São Paulo. Curiously, the coastal capitals showed lower levels of caffeine in the water supply than the inland capitals. This is explained, according to Jardim, by the fact that the marine outfalls or simple disposal along the shoreline somehow preserve the water sources.

Among the capitals they studied, Porto Alegre had the highest concentration of caffeine in water treated for human consumption, with an average of 1,211 nanograms per liter (ng/l), followed by Campo Grande, with 900 ng/l. Besides the consumption of mate in Porto Alegre, which is rich in caffeine, the water sources of the two cities are very impacted by sewage. Among the capitals with the lowest average rates were Porto Velho (3.0 ng/l), Fortaleza (4.0 ng/l), Recife (5.0 ng/l) and São Luís (8.0 ng/l). Five other cities studied had average concentrations between 100 and 200 ng/l: Vitória (101 ng/l), Cuiabá (114 ng/l), Belo Horizonte (119 ng/l), São Paulo (121 ng/l) and Teresina (188 ng/l).

Project
National Institute of Science and Advanced Analytical Technologies – INCTAA (2008/57808-1); Grant mechanism: Thematic Project – INCT; Principal investigator: Célio Pasquini (Unicamp); Investment: R$375,421.77 and $531,453.87 (FAPESP).

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