Team:EPFL/Description


Espress'EAU - Project Description

Background

Water is arguably the most important natural resource for human beings: it is used for agriculture, washing, cooking and most importantly, for drinking, as the human body needs a sufficient amount of water in order to function properly and to avoid dehydration. As a matter of fact, the water people drink should be free of any hazard.

In Switzerland, according to a survey conducted by the Swiss Society of the Gas and Water Industry (SSIGE), about 72% of the Swiss population drinks tap water on a regular basis1, and more than 40% consider themselves as “heavy users” of tap water, consuming it several times a day. According to the respondents, the taste, the high quality, and the low price make tap water in Switzerland this popular: roughly 90% of them consider the water quality as “good” and approximately 50% as “very good”.



However, even if a large majority of the population seemingly trusts the water quality, some concerns are raised about micropollutants. In the city of Lausanne, where 90% of the population drinks tap water regularly according to the annual report on tap water of 2019 2, 80% of the respondents also believe that finding small amounts of micropollutants in drinking water is “worrying”.

How do pesticides end up in our drinkable water?

The path of pesticides used for agriculture is more extensive and long than one would expect. As these products are applied to the crop, they will not only affect the organisms present on the plants treated with it, but also our water: either by rainfall, surface runoff or seepage into groundwaters, these chemicals will be found in the water sources that we use for cooking and drinking on a daily basis.



In the first case, the pesticides and their metabolites evaporate with the water and end up in the clouds that will eventually distribute them by rainfall. Besides, pesticides contaminate rivers and lakes due to surface runoff. Finally, the pesticides and their metabolites can seep into the soil and lead to polluted groundwater, which is an essential resource both for irrigation and for drinking.





Even though these products have been used since antiquity to support agriculture and ensure a sufficient food supply, when the concentrations are high enough, they can have many effects on our health, just as they do on the organisms that they are meant to get rid of 3. When the phytosanitary products used for agriculture arrive in our water, they can have several consequences on our health. Without even noticing it, if the water quality is not monitored, one could end up drinking micropollutants for years and get exposed to risks due to chronic exposition to these products. Indeed, several toxic effects can be caused by an exposition to pesticides and their residues over a prolonged period. Diseases such as cancer, Alzheimer’s disease, Attention deficit hyperactivity disorder (ADHD) along with damages to nervous, endocrine, and reproductive systems can appear due to the presence of pesticides on food, but also in drinkable water 4. It is thus beneficial to be able to easily monitor water quality to be aware of possible contaminations.



Do we find pesticides in the groundwater in Switzerland?

Since 2002, the presence of phytosanitary products traces is monitored at more than 500 measuring stations in Switzerland, with samples being collected and analyzed 1 to 4 times a year. We distinguish between three different types of traces:



  • Active substances, which are the ingredients that provide to the pesticides their biological function

  • Pertinent metabolites (products of metabolism deriving from decomposition and degradation of the original pesticides) that are considered to have the same biological function as the active substance or to be a comparable threat to organisms

  • Non-pertinent metabolites


The legal threshold in Switzerland for active substances and pertinent metabolites is set at 0.1 µg/L by the water protection “ordonnance” (OEaux), whereas no critical value for the non-pertinent metabolites is specified.

Monitoring observations gathered from 2002 to 2014 have shown that at roughly 2% of the stations (9/530), active substances were found in quantities above the threshold. Amongst those were found, in order of most detected substances, Bentazon, Atrazine, Metolachlor, Mecoprop and Metazachlor 5. The Plateau region,the most populated in Switzerland, is the most affected by pesticides contamination (figure from 6).



Additionally, at 5 stations, the pertinent metabolite of atrazine, desethyl-atrazine, was detected. Finally, non-pertinent metabolites were present at 20% of the stations.

What are the current detection methods?

Different analytical methods are currently used to analyze water quality and scan for the presence of pesticides along with other contaminants such as microbiological organisms and heavy metals. First, the analytes are extracted 7 from the collected water sample and then several techniques can be employed such as Gas Chromatography (GC) and High-Performance Liquid Chromatography (HPLC). Those can be used to determine which pesticide is present in the sample thanks to its characteristic spectrum based on retention times, and by using a calibration curve, the concentration of these products can also be determined. Moreover, these chromatographic techniques are often combined with Mass Spectrometry (MS), which fragments and ionizes the chemicals and then recognizes their unique footprint based on the mass and the charge of the fragments.



All these analytical techniques require sophisticated and expensive equipment, as well as well-trained staff to operate it. This makes it a lot more challenging to perform frequent and low-cost tests of water quality as a professional facility is needed.



There are also some commercial kits to test the water quality and the presence of contaminants from home, but they are often expensive (more than 100$ 8) and are based on a delivery system that requires sending a water sample to a bigger facility, where professional instruments will be used to test the water quality. Thus, these kits do not generate a viable solution to perform water quality tests in a do-it-yourself fashion.

What is the problem?

Chlorothalonil is a pesticide that was added to the Swiss list of banned substances on the 1st of January 2020. The legal threshold for Chlorothalonil and its pertinent metabolites in water was fixed to 0.1 µg\L in August 2019, matching the limits for other pesticides and their metabolites. Several cases of Chlorothalonil contamination have been reported in the Canton of Vaud 9 in Switzerland during the past year. As a consequence, water sources had to be closed where the threshold was exceeded. Swiss communes should adapt their water sources to Swiss standards within two years.



One way to prevent the closure of water sources is to regularly monitor their quality. However, small villages are not very populated, thus the legal frequency of tests is only once or twice per year, as the latter is indexed according to the number of inhabitants. Because there exists a limited number of specialised laboratories, with limited personnel to conduct experiments, bigger communities are prioritized over smaller ones to not overload analytical laboratories, and so small communities feel “left alone” in their fight against water contamination. Moreover, the cost of tests can rapidly become an important budget for small villages if the testing frequency is increased with traditional methods, as they are rather expensive. A lot of time could also be saved by limiting the samples transportation time from the village to the laboratory. A low-cost, easy-to-use and generic system would help those communes assess their water quality on-site, rapidly take action, and eventually provide the possibility to perform more in-depth testing in case of a threat of water contamination.

Espress'EAU

We aim at creating a system that is low-cost and easy-to-use that enables small communities and individuals to test their own water samples without sophisticated equipment and training, while guaranteeing the safety of its users. Espress'EAU is intended to serve as a fast and generic preliminary analysis of water quality, reducing the time between the sample collection, transport, and testing. Small communities will be able to test their water more frequently and thus take action as fast as possible in order to avoid distributing contaminated water to the population.

Stakeholders

Our project idea originated from an actual local issue in Switzerland and it was essential for us to provide a solution that would be useful to local communities and people . Thus, it was natural that we reached out to local actors involved in water quality testing to help us shape our project. We contacted the water service of Lausanne that informed us about the current methods of detection of pesticides and provided us help to initiate our project, as well as the Association des fontainiers de Suisse Romande, which is responsible for the safety of the drinkable water network in the region, that helped us understand how pesticides affect their work and how our project could integrate into the actual framework of water quality testing.

References

  1. Aqua & Gas [Internet, visited on Sep 14 2020]. Available at: https://www.aquaetgas.ch/fr/eau/eau-potable-eau-souterraine/20170930-trinkwasser-fa-20172009-imageanalyse/
  2. Sondage eau Lausanne 2019 [Internet]. Official website of the city of Lausanne [visited Sep 14 2020]. Available at: https://www.lausanne.ch/officiel/administration/securite-et-economie/eau.html
  3. The Dangers of Pesticides [Internet]. Scitable [visited Sep 23 2020]. Available at: https://www.nature.com/scitable/blog/green-science/the_dangers_of_pesticides/
  4. Brève histoire de l'utilisation des pesticides : du soufre au glyphosate en passant par le DDT [Internet]. Agora [visited Sep 23 2020]. Available at: http://agora.qc.ca/documents/breve_histoire_de_lutilisation_des_pesticides_du_soufre_au_glyphosate_en_passant_par_le_ddt
  5. État et évolution des eaux souterraines en Suisse. Résultats de l’Observation nationale des eaux souterraines NAQUA, état 2016.
  6. Plateau [Internet]. Confédération Suisse [visited Oct 26 2020]. Available at: https://www.nccs.admin.ch/nccs/fr/home/regions/grandes-regions/plateau.html
  7. Analyse des pesticides dans l'eau [Internet]. SIGES Seine-Normandie [visited Sep 23 2020]. Available at: http://sigessn.brgm.fr/IMG/pdf/analyses_pesticides_brgm.pdf
  8. Pesticides Eau Consommation [Internet]. kudzu Science [visited Sep 23 2020]. Available at: https://www.kudzuscience.com/eau-sols/19-pesticides-eau-consommation.html
  9. Du chlorothalonil dans l'eau du robinet de plusieurs communes vaudoises. [Internet]. RTS [visited Sep 14 2020]. Available at: https://www.rts.ch/info/regions/vaud/10768189-du-chlorothalonil-dans-leau-du-robinet-de-plusieurs-communes-vaudoises.html

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