Unicamp researchers detect emerging contaminants using new analytical techniques
Emerging contaminants are so called because they lack legislation, that is, establishing maximum values allowed in matrices such as rivers, groundwater or drinking water. However, the regulatory process is not trivial. A classic example of these contaminants is 17α-ethinyl estradiol, a hormone used in contraceptive pills, whose internationally established criterion based on toxicological tests, which does not pose a risk to human health, is 30 picograms (millionths of a microgram) per liter. It turns out that, in practice, there is no analytical tool capable of quantifying such a low concentration of this contaminant in water – therefore, there is no way to transform the criterion into law, even knowing that the hormone is harmful to us.
“The equipment we have works with a limit of 10 nanograms per liter, around 300 times higher”, compares professor Cassiana Carolina Montagner, responsible for the Environmental Chemistry Laboratory at the Institute of Chemistry (IQ) at Unicamp. “If we detect the hormone in this equipment, it means a health risk, as it is well above the criteria described in international literature. But, if we don't detect it, it doesn't mean the hormone is absent; perhaps it is present in concentrations that the equipment cannot measure. It is a false interpretation that we are always trying to correct. Today, no country in the world legislates on 17α-ethinyl estradiol because there is no way to monitor it at this concentration.”
The IQ professor notes, however, that ecotoxicology is an area that has been advancing rapidly and should offer new values soon. “The literature on emerging contaminants is growing a lot in the interdisciplinarity between monitoring and analytical techniques. One truth that ecotoxicology shows us is that the concentrations of compounds that pose a risk to health and the environment are very low. We are making more and more progress in testing and pointing out maximum values (criteria) at lower concentrations, while analytical instrumentation seeks to quantify these compounds at these concentrations.”
Cassiana Montagner's group has two published works aimed at this scientific advance in relation to emerging contaminants, both in vehicles from the Brazilian Chemical Society: the first in Química Nova, seeking to outline a national panorama of research to find out what classes of emerging contaminants are of greater interest, in different matrices; the second work was published this year in the Journal of the Brazilian Chemical Society (JBCS), surveying what is already known about the topic, based on ten years of research at the Environmental Chemistry Laboratory – and focusing on the state of São Paulo, which has the highest population density in the country and high water requirements for irrigation, industry, livestock and human consumption, in that order.
The review of research on emerging contaminants, published in Química Nova, resulted in a list of 56 articles published over 20 years (1997-2017), which reveal the occurrence of around 200 compounds in waste, surface and drinking water in 11 of the 26 Brazilian states, plus the Federal District. The Southeast region presented the largest number of studies, mainly São Paulo, which has consumption patterns similar to those of developed countries, accumulating, however, environmental problems typical of developing countries, especially related to the lack of sanitation.
The JBCS article portrays the occurrence of 58 contaminants in 708 samples of drinking, river, underground and waste water, all collected in the state of São Paulo, between 2006 and 2015: there are nine hormones, 14 drugs and personal care compounds , 8 industrial, 17 pesticides and 10 illicit drugs. “In fact, we already had a lot of occurrence data in different matrices and we wanted to interpret the numbers for a risk assessment. We created a database based on theses and articles and searched for criteria in international literature that could guide us both in relation to the protection of aquatic life in rivers, and for human health considering the intake of the tap water we consume”, explains Cassiana Montagner.
According to the professor, following the literature criteria, several compounds presented a risk to aquatic life, such as caffeine, paracetamol, diclofenac, 17β-estradiol, estriol, estrone, testosterone and triclosan. In relation to the criteria for drinking water, 22 compounds were present, with no risk of adverse effects in the concentrations found. “It is important to look at the protection of aquatic life, which sometimes is not a priority on the agenda, but which we need to consider, even now in view of the sustainable development objectives established by the UN. Human health draws more people’s attention and in principle there would not be a direct risk associated with the compounds, except for the hormone, which is very potent in our body.”
Chronic exposure
In addition to the hormone in the contraceptive pill, pesticides are very active and are also present in these residual concentrations, which leads the Unicamp researcher to clarify another important point. “The concentration is lower than the values allowed in our legislation and in other countries, but chronic exposure to pesticides and the endocrine or even neurological effects they can cause are not included in the maximum value established – and water is a route of exposure continuous, a direct source from where we drink every day. And, of course, we also have food intake and, depending on the region, inhalation of pesticides.”
The drugs are equally bioactive and their molecules are in drinking water and rivers, although in concentrations lower than the doses ingested for treatment. “It is more of a problem associated with ingesting a little, however, every day. People get scared when we say that we drink drugs, hygiene products, caffeine and even cocaine. The source is the same, they are all together. The effects are not acute, no one will die tomorrow because of it. The issue that draws attention is the triggering of a series of diseases that can be exacerbated due to this chronic exposure”, ponders Montagner.
Another aspect highlighted in the JBCS article is that the concentrations of the various compounds found in sewage and rivers are of the same order of magnitude, even in the Southeast, which has one of the highest rates of sewage treatment in the country. “Sanitation rates in São Paulo are considered good to excellent. The indication is that sewage treatment does not remove the compounds or that there is a lot of raw sewage being released into the water sources. Or, even, that conventional treatment is not effective, which requires improvements in existing systems. We researchers are clear that the quality of tap water is a reflection of the source: if the contaminants in the sewage go to the river, we will also find them in drinking water.”
System modernization
In Cassiana Montagner's opinion, the basic sanitation system must be rethought in its entirety, in order to meet the current standard of living. “A few decades ago, we did not have such a large exposure to this amount of compounds, except for some metals and pesticides. The traditional system was not designed for this type of contamination. In a lecture, I encouraged the audience to find out where the water that reached their homes came from, go to the spring and ask themselves if they would swim in it. It is a way for the population to get to know their surroundings, make an initial assessment and question the government bodies.”
The Unicamp professor assures that there is technology to purify water, even eliminating emerging contaminants, and that it could be adapted to current plants, both water and sewage treatment. “I have been working with collaborators to bring the technology used in other countries to the Brazilian reality. It turns out that it is necessary to invest in replanning plants and also in research. As those responsible are not charged, there is not much motivation. In the United States, for example, where I lived for a few months, it is common to drink tap water and swim in the rivers that run through urban centers. There, conventional treatments are only used on water collected from protected sources: the sewage goes through a series of treatments and the effluent released does not impact the river. In other words, there is an entire basic sanitation system capable of protecting animals and human beings from waste generated by anthropogenic activities.”