We believe that an important part of the problem, regarding bottled water consumption, is that many people don’t know about the existence of microplastics and EDCs, because there is not much information at their reach on this matter. One of the reasons being that, to our knowledge, there is no quick and reliable method to quantify them. Considering this and acknowledging that it would be very difficult to meaningfully dimmish the bottled water consumption in our community, we decided to design a biosensor to detect the presence of EDCs in water, with the aim of raising awareness about them and determine preventive actions to reduce their intake (read more here).

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A fundamental part throughout the development of the biosensor were our Human Practices, as all the activities we performed gave us insights to improve and helped us shape our project. For instance, we reached several experts through interviews or consultancies, who gave us feedback that allowed us to identify areas of opportunity. Furthermore, we collaborated with the Cántaro Azul non-profit organization to help them fulfill their mission of providing safe water to rural communities. The interviews we gave were also a great opportunity to participate in diffusion forums, like public radio and talk about our project, as well as the problem of the EDCs on a national scale. Moreover, we conducted surveys to know people’s plastic consumption habits and have a better understanding about the dimension of the problem. Additionally, our legislative framework analysis allowed us to identify a regulation, in which the maximum permissible limits of EDCs and microplastics could be included.

Cántaro Azul: A Funding through Webinars

Why did we do this?

In Mexico, there is a large inequality gap in access to adequate and appropriate water, and sanitation services, as well as in the pursuit of healthy environments.
This gap is supported by the fact that in rural areas, only 42.6% have water every day with an exclusive toilet and connection to the drainage network or septic tank [3] 

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Another fact is that only 14% of indigenous multigrade and community schools have some means to ensure that children have access to water for human consumption. Also, it is estimated that, in Mexico, only 43% of the population has safe water [4]  and according to data from the INEGI Census of Schools, Teachers and Students of Basic Education, there are around 25 schools in Mexico 1.7 million students that do not have access to a public water network

These figures show the impact of the problem existing in Mexico regarding water sanitation and which is directly involved in the cause of diseases. This reduces the possibility of enjoying the human right to water and sanitation for the rural populations of Mexico [5] Recognizing this problem, we decided to collaborate with Cantaro Azul through which we sought to contribute to the achievement of Objective 6 (“Clean water and sanitation”) of the Sustainable Development Goals.

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As part of this collaboration, we offered a series of webinars that gave participants an overview of the impact of plastic on the environment, the effect of EDCs on different diseases ,such as obesity and the role of these plastics in the Mexican industry. The objective of this was to raise awareness about the impact of plastic on daily life. These webinars were open to the public and had a cost of $3 USD and incentives to the community of our university.

What did we learn? 

The fact that we organized these webinars so that members of our society could participate was of great importance, as we raised awareness about this huge problem for our colleagues, students and members of our community. We also learned a lot ourselves; specially about the needs of our world regarding plastic and its correct disposal.

In addition, it was achieved to have the knowledge of how EDCs cause different diseases including diabetes, which has been one of the most impactful diseases in the last few years. Given that Mexico occupies the first place in obesity, this webinar was useful to spread information about this disease. It involves not only genetic factors, but is generated by an accumulation of various other external variables that trigger it.
 

Particle analysis in bottled water for collaboration with Cántaro Azul

Why did we do this?

A very important part of our project was to determine the intake of microplastics by people who consume bottled water, so we used the Zeta Sizer device from our university to analyze the presence of nano and microparticles in bottled water samples from various brands at different conditions, like sun exposure and impact (read more here). This would help us to have a better idea of the EDCs consumption, as these substances are frequently used in the manufacturing of a wide range of plastic products; thus, being present within the majority of microplastics.

What was the impact of this activity on our project?

In addition to offering people webinars focused on providing knowledge and awareness about the impact of plastic on our lives, the money collected from the first round of webinars was donated directly to Cantaro Azul. We collected aboutt $40 USD. It may not seem as much but it was the first time we did it. We hope we will open more Webinar rounds in the future. We hope that the money we collected will be used by Cantaro Azul to continue supporting marginalized communities in Mexico where there is no access to clean, ready for human water.

We will keep collaborating with this great organization in the future (to learn more about Cántaro Azul click here).
 

This information would also be helpful to the Cántaro Azul organization, since they aim to provide safe water and improve the health of people living in rural communities of Mexico. Specifically, many of their programs operate through water disinfection and purification systems, promoting at the same time water consumption, hygiene, and nutrition habits [6]. For the development of such programs, they commonly use plastic water jugs to provide and store water, which are constantly washed and reused. This constitutes a good practice to ensure access to safe water for the communities; however, the organization is unaware of the microplastics and the EDCs problem and how the multiple reuses and the sun exposure of the jugs could contribute to the particle liberation in water. For that reason, the results we obtained from the water samples analysis at our Campus will be shared with them, so that they know the conditions that could make the water jugs unsuitable for use due to the presence of microplastics and EDCs, which could have a negative impact on people’s health.

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Furthermore, even though we analyzed water from plastic bottles, many of the brands also manufacture the 20 L (5.28 gal) plastic jugs that the organization uses, so the data we share might give them some insights on which condition has a major effect on each brand’s jugs.

What did we learn?

The results we got from the analysis with the Zeta Sizer and the determinations we made about the factors that could cause a change in the dimension and the distribution of plastic particles in bottled water form different brands, helped us to have a reference of the possible microplastics daily intake and thus the approximate EDCs concentration (read more here).

Moreover, by working with the organization and getting to know more about their programs, not only did we learn about their practices to maintain water purification systems and the importance of plastic water jugs to perform this activity, but we also got aware of the bottled water consumption among the communities in which the organization has presence; for example, as part of the “Agua Segura en Escuelas” program, Cántaro Azul has noticed that children in schools buy many water bottles, as they don’t have access to potable water or it is of poor quality and cannot be consumed. In the words of the organization: “the drinking water networks do not guarantee the quality of water for human consumption, due to poor disinfection, purification, storage and distribution practices…many families must choose between drinking non-potable water…or purchasing bottled purified water offered by the private sector” [7].

This situation has significantly increased the bottled water consumption of children and their families, which, besides being an expensive option, could affect their health because of the microplastics intake. Contemplating this, we understood how the organization tries to provide safe and cheap water by constantly refilling big plastic jugs; however, the conditions in which such jugs are stored and used must be considered, that is why we think that sharing our analysis and information with them, might be useful to improve their practices and achieve their goal of providing safe water to the communities.

What was the impact of this activity on our project?

The Zeta Sizer data contributed to confirm the presence of microplastics in bottled water samples and helped us to determine how different conditions have a particular effect in the number of microplastics found in water samples from distinct brands. This was very important to us, since it gave us a starting point to estimate the concentration of EDCs we might detect with our biosensor, depending on the conditions of the sample we analyze. In addition, based on this information, we can establish certain preventive measures to reduce the intake of microplastics (and therefore of EDCs), at least due to the bottled water consumption (read more here). Also, as we previously stated, all of that could be useful as well to enhance Cántaro Azul’s usage of the water jugs.

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​On the other hand, as we found in literature [8], one of the problems of the Mexican population regarding water consumption is that people do not trust the quality of water, so they rather buy bottled water. On this matter, the collaboration with Cántaro Azul by knowing about their work and the strategies they implement in rural communities, made us realize that such problem is even greater in these locations, where the access to potable water is very limited.

We know that there are many mechanisms to purify water from several contaminants, but, to our knowledge, none of them help to remove the EDCs derived from the microplastic particles (at least none of the methods available in our country), so this was one of the reasons we reconsidered the initial idea of our project, which consisted only in detecting the EDCs present in water, but not in degrading them. Therefore, we decided to start looking for effective ways of eliminating these substances and we came up with the idea of using the laccase enzyme because of its oxidative capabilities against micropollutants and the possibility to produce it on large scale (read more here); nevertheless, even though we have performed several experiments for the laccase expression in E. coli, it wouldn’t yet be feasible to implement this part of the project for drinking water purification, as we still haven’t quite developed the methodologies to do so. 

2. Ciudadana Radio 660 am with Rodrigo Reyes

Why did we do this? 
This radio program has a radio station called Terramar that touches on environmental issues so the interview served as a guideline to expose how microplastics affect the environment, to human health and in general to living beings giving an overview of the problems generated from these microplastics to the population listening to this radio channel and serving as a means of transmitting information and knowledge.

What did we learn?
Conducting this interview helped us explain and raise awareness among people listening to this channel about how basic consumer products such as water bottles, juices and soft drinks have a huge health impact. In addition to understanding the types of regulations that exist for these products and in which part our project will be to these regulations. 

 

What was the impact of this activity on our project?
The problematic of EDCs toward human health is impactful, therefore, conducting this interview allowed people to become more aware of this situation, to which we are proposing an innovative solution. This is something that gave much diffusion to our project in the Mexican population.

3. La autentik radio 92.5 FM with Candido Hernandez.
 

Why did we do this? 

This broadcaster reached out to us because they think that our project is a real catch. They are really interested in sharing science and projects related to students and young people. La Autentik is an important broadcaster in a town named Metzquititlán, in Hidalgo, Mexico. Candido Hernández was really excited for us to tell our project and share it in the town for other young people to start seeking and getting interested in science. 
 

What did we learn?

Communicating our project effectively through language accessible to most of the Mexican population that is not necessarily related to a scientific way of talking was one of the things that this interview taught us. Besides, it was a refreshing experience to talk about motivating  the population and giving exposure to the existing Mexican talent. 

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What was the impact of this activity on our project?
We expanded our reach to other communities in Mexico. Hidalgo is a neighboring state to ours. We were happy to share our project and create plastic consciousness, for people to reduce their plastic consumption in other parts of the Republic. 

Legislative framework

Overview

As we have mentioned before, plastic is not only an environmental issue, but a human and wildlife health matter. Summing up, the impact of the degradation of plastic polymers results in the accumulation of EDCs in water bodies that we as humans and marine life are highly exposed to [9] [10].
To see more information, visit the section of SDG´s where you can find more details about this health and environmental problems.

The focus we want to give to our “Disrupting Disruptors” project is to take it a step further and provide a reliable measurement and further degradation method. This is for industry to guarantee clean water and sanitation, health and wellness to every drinking water consumer as their human right and human basic need, as it states in National Commission for Human Rights.[11]

Interviews with specialists

Distribuidora Quimica Tauro, specialists in water treatment with Ernesto Robles and Irene Robles

Why did we do this? 

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It was carried out in order to know the water sanitation scenarios in Mexican industries, also knowing under what regulations these water treatments are attached and what treatments are currently available for wastewater treatment in Mexico. Simildly, he discussed with specialists the parameters that are considered to be able to establish that the treated water is free of pathogenic microorganism or some other parameter outside it.

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What did we learn?

We learned about the technical parameters that are measured to consider that a water is ready for consumption either human or as part of a process in the industry, as well as the maximum permissible parameters in water treatment.

The existing regulations and the new regulations that will enter into force for the discharge of water from different industries such as the textile industry, metalmecanica, drinks and food that are polluting the drainage and drinking water of some rivers in the Mexican region were known. This helped us to direct our project as it was checked with the specialists that none of the existing regulations in Mexico nor in NOM-127 for human consumption take into account EDCs as part of a measurable parameter drinking water because  there are currently processes to treat water and remove very small particles such as reverse osmosis, however, these EDCs are not being taken into account within a measurable parameter in the degradation of the bottles used to wire drinking water as once you have the final presentation of the water bottle the parameters that occur after this packaging are not measured. [14]

On the other hand having the interview allowed us to visualize the scope of our project because we did that the process we are developing is more economically accessible compared to the existing processes in the market for treating water then our process would become more profitable and therefore more attractive for companies to acquire our product and with this we would manage to give solution to the water treatment by obtaining drinking water and safe for them

Likewise, there was a perspective on how industries should consider treating their water regardless of which area they are covering, as they should stop seeing it as a requirement and more as a contribution to environmental care and population health.

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What was the impact of
this activity on our project?

It helped us see how our project involving new technologies both biological and non-biological can help companies in many industries in their wastewater treatment as Mexican regulations are increasingly demanding as part of most companies. specifically to the drinking water industry as it has a direct impact on consumer health.

The area of opportunity with our project in this sector is of great contribution to have healthy populations and sustainable ecosystems. Especially considering that most companies begin to have a sense of responsibility and respect for the environment and in addition our project could be more profitable to the companies.(To know more about it click here)  

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Interviews with Ana Guadalupe Rodríguez Hernández

Ana Guadalupe specialist in nanomaterials with a current project in nanoplastics

Why did we do this?

The engineer is dedicated to the characterization of nanoplastics and also studies the impact of them on health from the water industry and the cosmetics industry and its derivatives.  

This is why the interview with the engineer was carried out in order to further enrich our project and to know different points of view as well as to know the real approach of EDCs in human health.
 

What did we learn?

Specifically speaking of EDCs and their health damage, Bisphenol A is a mutagenic component that comes from polyethylene degradation and phthalates come from PET degradation.

These EDCs cause interfaces with hormone signaling, produce changes and alterations in human physiology and metabolism, and PET due to its absorption capacity can alter human receptors when it is consumed unintentionally, this can be very dangerous to health because the innate immune system only recognizes these particulates at the nanoplastics level, triggering the immune response and producing a cellular alteration. 

At the genetic level there are 4 over-expressed regulators that may be related to various diseases such as cancer. Likewise, these EDCs intervene in the path of calcium, nitrous oxide, and ionic compounds present in the tissues causing the smooth tissue and at the intestinal level to generate involuntary contractions altering the entire regulatory system of our body.

What was the impact of this activity on our project?
 

From the information provided by the interview we enriched more our project and the impact that we would have on it in the field of human health would be important since in Mexico today the reason why they do not exist in the regulations or in the norms these Measurable parameters such as EDCs in water is because there is no knowledge on the subject. This path of research on the subject has recently been opened in Mexico.

We as a research team can generate the knowledge and are giving a possible solution to this problem that covers many areas of Mexican industry and various products that have not yet been investigated in depth and of which are unaware of its impact to the cheers. (To learn More about it click here)

Plastic Consumption Surveys

Interviews with Ingrid Marión Lopéz Mejía

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Interview with Ingrid Lopéz  chief of the department of water and Luis Pacheco chief of the department of drinking water and Bertha Muñoz technical director.

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Why did we do this?

Currently, the part of the drinking water regulation in Mexico is not well defined and is why as part of having greater knowledge in the existing regulations for the use and treatment of drinking water, I consider conducting an interview with experts in the subject and with it being able to sustain our project.

What did we learn?

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It was corroborated with the experts on the subject that so far there is no regulation involving EDCs in drinking water and the industries dedicated to this sector are based solely on NOM-127 for drinking water consumption, this does not cover EDCs or microplastics within their regulatory framework.

Likewise, it is known that at present around 80% of the population in the State of Mexico has access to drinking water, being that it is a right that every citizen should have this resource as a right to health and a dignified life. 

The specialists consulted also carry out physicochemical and organoleptic studies based on NOM-127, as regards the organoleptic studies the water should be considered colorless and inholory and which are considered as the first line of study to determine that the water is clean.

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What was the impact of this activity on our project?

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The Mexican regulation applicable to the use and consumption of water does not yet include measurable parameters such as EDCs or microplastics, however, our project may be a precursor that these parameters can be included in this regulatory standard as part of a modification to this one in order to facilitate consideration by the agencies that carry out these analyzes within the analysis of drinking water and thereby contribute to consumer health and a better quality of life as standards are constantly evolving by new technology and advance in knowledge it may be possible to achieve a change in it that includes EDCs in the future. (To learn more about it, click here) 

Why did we do this? 

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This survey had the objective of identifying the plastic production footprint that people who live in the metropolitan area of Mexico have, and more specifically, understanding the exposure that they have to microplastics. 

We seek to calculate the microplastic’s footprint people have by analyzing the number and type of plastics that they generate in a week (i.e. plastic bottles, food wrappers, plastic bags, etc.). Once this data was collected, it was analyzed and processed to understand habits related to the exposure to plastic, and how they may affect people’s health.

Finally, by doing this we aimed to raise awareness of the impact that the generation of plastics has and the general trends that people have regarding this issue.

What did we learn?

Along this research we were able to understand the perception that the Mexico’s City Metropolitan Area population had regarding microplastics, plastic production, and their exposure to all this waste. Plus, through the quantitative analysis performed, we were able to identify how much waste people generated and how this translated into microplastics generated.

For instance, thanks to this survey we learned that, even though microplastics are a real threat that can impact negatively the health of people, people in the metropolitan area are not really aware of what this type of waste an one example is that actually are more women with 41% who have a low impact with their carbon footprint, so they have a lower plastic production with 48.7% compared to men who have a high plastic production with 68.6% also those people who have access to drinking water with 41.5% are the ones who consume the most bottles compared to those people who do not have access to drinking water who represent 37.6% of the metropolitan population. Therefore, more men with access to drinking water will produce more plastic waste in the metropolitan area of Mexico. 

In accordance with the above and with the results obtained from the survey, people over or equal to 30 years of age, whether women or men with a normal lifestyle and with access to drinking water, are the group that is currently producing more waste from bottles of water plastic. However, when evaluating the number of plastic pieces produced per week, it turned out that when considering the average of the comparative factor of the type of gender, it did not have a significant impact in terms of the number of plastic pieces produced by people who have more than 30 years with a normal lifestyle and access to clean water. 

On the other hand, it was observed from the results that currently there are more minors who have knowledge about microplastics with 38.8% of the population that are completely aware of the damage that they cause. Therefore, those people who do not have access to drinking water turn out to be more aware of the damage that microplastics can cause in the long term and which is consistent with the results described above, since those people who have access to drinking water are the oldest. producers of plastic and with less awareness on this issue. 

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A relevant aspect that motivated us to continue with the research of our project was that the trend of people who use bottles to store their water use materials other than plastic, resulting in that this type of people are those under 30 years old representing 60.4% of the mostly female gender and with a lifestyle with a low impact on the carbon footprint, which turns out to be a total of 63.2% of the population that has a low production of plastic bottles, in this sense the parameter of access to water drinking turned out to be non-significant. It also turned out that the type of material that is used as an alternative to plastic is considered reusable by most of the respondents. 

Regarding the analysis of different types of brands, it served us as a measure as a reference to the development of our biosensor since the results of the surveys showed that most people prefer the consumption of bonafont because they consider it has better water quality and is a brand that cares about the environment in comparison with the Great Value and “Casa del agua” brands, which were obtained a lower score considering it as low quality water by the respondents, it was also observed that brands such as Fiji, Evian and Rainforest were considered as brands with a high cost and not many of the respondents are aware of these. 

From the responses of the respondents it was possible to have an even clearer approach about our project since they knew the views, preferences and needs of the population that we sought to give a benefit in the first instance because, while it is true that half of the people surveyed have drinking water in their homes, there is also another 50% of this population that does not have drinking water in their homes. In addition to the fact that from this perspective, the respondents disagree that the water they consume is completely healthy since at least half of them have seen plastic or particles float in their daily drinking water, which is why they have considered using additional technology to have healthier water consumption, this technology includes a filtration system in their homes.

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What was the impact of this activity on our project?

This survey was of high added value to our project because it provided us with additional information that we use to evaluate the potential impact of our project on the daily life of Mexicans, in addition to knowing which population group is the one that produces the most plastic waste and because they do it, just as it allowed us to know which people are the ones with the lowest consumption and therefore the lowest production of plastic products. What caught the attention of this was that patterns such as young age and with a low impact lifestyle remained constant in terms of the production of their plastic in the environment without taking so much into consideration the gender to which they belong, this being It is very helpful for us because it allows us to clearly assess the trends to a greater or lesser consumption of plastic products that is related to the development of certain diseases in their long-term consumption. (To learn more about of our completely results regarding to this click here) 

Meetup expert consultation

Why did we do this?

As part of our collaborations, we hosted the LATAM Meetup 2021, where different teams from Mexico, Costa Rica, Brazil, Portugal, and Spain got together through an online gathering to present their projects, share ideas, and receive feedback from our experts panel (read more here). This was intended to help teams prepare for the Giant Jamboree as well as the iGEM Design League, and to know the teams’ members for possibly establishing collaborations.

Besides getting to know the projects of our fellow iGEMers, this activity gave us the opportunity of reaching out to different experts, who provided valuable feedback for our project. Specifically, Dr. Yolanda Guadalupe García Huante helped us a lot. She has focused in studying regulatory mechanisms to produce secondary metabolites of Streptomyces, and in the recombinant production of enzymes from thermophilic fungi. Furthermore, she has recently finished a postdoc in the University of Texas at Austin, related to engineering CRISPR-Cas proteins and the expression and characterization of retrons in yeast. Her comments on our ideas about the biosensor and about the production of the laccase enzyme for its usage in the EDCs degradation, contributed to better define our protocols and our strategy of implementation.

 What did we learn?

When we were preparing our presentation for the Meetup, we tried to include all the technical aspects of the project and the lab work we had done by that time. However, we didn’t realize that we hadn't considered several aspects, which came to our notice when Dr. Yolanda García asked some questions and gave us feedback at the end of our presentation. One of the things she told us was that it would be important to add enzymatic assays in our protocols to test the laccase activity and to perform a biochemical characterization of the enzyme and the microorganism from which we obtained it, in order to know the optimal operation conditions. Additionally, we hadn’t defined whether we would extract and immobilize the enzyme or use a complete microorganism for the degradation process, so she told us that we should evaluate the pros and cons of each alternative to choose the one that best suited our idea.

Another aspect we hadn’t thought about was that, in case our biosensor became 100% functional, who would be our end users (water purification enterprises or people from the community), which she said was very important to determine for the implementation of the project.
All these observations were very useful and helped us to enhance several parts of our project.

What was the impact of this activity on our project?

Following the recommendations of Dr. Yolanda García, we performed laccase induction assays with guaiacol and citrate buffer with colorants to measure the enzyme’s activity as well as several experiments for its the characterization (see the protocols here); however, we still haven’t decided if we are going to use the purified and immobilized enzyme or the complete microorganism for the degradation of the EDCs. On this matter, it is important to notice that, as the biosensor was the main part of our project, we initially dedicated all our time and effort to its development, leaving the degradation part as a secondary priority, that is why there still many aspects we need to work on regarding this section of the project; nevertheless, we are in the process of doing so and incorporating all the observations and feedback of Dr. Yolanda García to our project.

On the other hand, we think that once our biosensor and the degradation process are fully working, our device could be used by both enterprises and people from the community.

References:

[1] Rodwan, J. (2021, July). Bottled water 2020: continued upward movement. U.S. and International Developments and Statistics [Online]. Available: https://bottledwater.org/wp-content/uploads/2021/07/2020BWstats_BMC_pub2021BWR.pdf

[2] Alexedo (2021, July). Mexico’s Battle Against Bottled Water [Online]. Available: https://www.alxedo.mx/blog/mexicos-battle-against-bottled-water

[3] INEGI ( 2017). National household survey. [Online] Available: https://www.inegi.org.mx/programas/enh/2017/

[4] UNICEF/WHO (2017). Progress on household drinking water , sanitation and hygiene. [Online] Available: https://data.unicef.org/resources/progress-drinking-water-sanitation-hygiene-2019/

[5] Cántaro Azul (2017). Problematics of drinking water in México. [Online] Available: https://www.cantaroazul.org/problematica

[6] Cántaro Azul, (n.d.). Agua Segura en Escuelas [Online]. Available: https://www.cantaroazul.org/agua-segura-en-escuelas

[7] Cántaro Azul. (n.d.). NuestrAgua Franquicia Social [Online]. Available: https://www.cantaroazul.org/franquicia-social

[8] Alexedo (2021, July). Mexico’s Battle Against Bottled Water [Online]. Available: https://www.alxedo.mx/blog/mexicos-battle-against-bottled-water

[9] E. Diamanti-Kandarakis et al., "Endocrine-Disrupting Chemicals: An Endocrine Society Scientific Statement", Endocrine Reviews, vol. 30, n.º 4, pp. 293–342, junio de 2009. [Online]. Available: https://doi.org/10.1210/er.2009-0002.

[10] E. Ingre-Khans, M. Agerstrand y C. Rudén. "Endocrine disrupting chemicals in the marine environment". Department of Environmental Science and Analytical Chemistry (ACES). [Online]. Available: https://balticeye.org/globalassets/fokusomraden/farliga-amnen/edcs-in-the-marine-environment-report.pdf

[11] I. Vázquez del Mercado, Ed., "El derecho humano al agua potable y saneamiento", ISBN: 978-607-729-084-1, Mexico City, Informe de la Comisión Nacional de los Derechos Humanos, diciembre de 2014. [Online]. Available: http://appweb.cndh.org.mx/DerechoAgua/archivos/contenido/CPEUM/H1.pdf

[12] R. García-Arrazola, «Centro del Agua para América Latina y el Caribe,» Revisión del marco regulatorio de contaminantes emergentes en el agua para México y el mundo., 26 08 2013. Biblioteca UNAM.

[13]. COFEPRIS, "Water", Mexico, NOM. [Online]. Available: http://transparencia.cofepris.gob.mx/index.php/es/marco-juridico/normas-oficiales-mexicanas/agua

[14] Salud ambiental. Agua para uso y consumo humano. Límites permisibles de calidad y tratamientos a que debe someterse el agua para su potabilización, NOM-127-SSA1-1994, SEGOB, Mexico, 1994. [Online]. Available: http://www.dof.gob.mx/nota_detalle.php?codigo=2063863&fecha=22/11/2000

[15] Límites máximos permisibles de contaminantes para las aguas residuales que se reusen en servicio público., NORMA Oficial Mexicana NOM-00.-ECOL-1997, SEGOB, México, 1997. [Online]. Available: http://www.ordenjuridico.gob.mx/Documentos/Federal/wo69207.pdf .

[16] J. Macías Rábago. "Gaceta del Senado". Gaceta del Senado. https://www.senado.gob.mx/64/gaceta_del_senado/documento/98022