Mexico City

Santiago Mota (MDE + MDes E&E ‘20)

There are 318 traditional markets in Mexico City with 77 thousand stores and half a million families dedicated to them. Located in the center of the urban life, both physically and metaphorically, these markets receive the fresh fruits and vegetables from the Mezquital Valley everyday through a gordian knot that includes farmer bodies, vegetable boxes, diesel-driven trucks, large-scale logistical networks and food supply chains.

The Central de Abastos, the pinnacle of this bundle of machines, human bodies and vegetables, is one of the largest food supply markets in the world. Fresh produce from different places, including the Mezquital, arrive in trucks and flows through this building for distribution into one of the 300+ local markets and 1000+ produce shops in the city. And at the back-end of this market of markets, lies a generic space that is replicated at different scales but with the same programmatic function throughout the city, and most importantly, the same flexibility. Here, the scale of the truck, the kiosk, the box and the vegetable match (Figure 1).

Figure 1: The Central de Abastos, the nodal point of entry for edibles to Mexico City.

A truck fully packed with onion, lettuce or radish is redeployed into a component of the market, a space that addresses the transformation of produce from the ground to the tables, but also the transformation of pathogenic lifeforms within the vegetables and fruits. A kiosk and a food vending spot, sometimes side by side, sometimes one and the same (Figure 2).

Figure 2: Inside a typical market in Mexico City, the scales of the truck, the kiosk, the box and the vegetable are deployed.

Entamoeba histolytica thrives here. It is not able to move alone, as it relies on motorized vehicles, human labor, edible transports and plastic containers. As one of the first agents defined as a pathogenic and efforts for developing a microscope for epidemiological purposes were driven by the connection of this  protozoan with human urban agglomerations and outbreaks of dysentery. Humans are regarded as the definitive host of this invasive species as it has co-evolved for thousands of years with humans and today there are no other meaningful reservoirs.

Entamoeba histolytica has developed a deadly strategy,  quietly occupying some human bodies while shedding a geometric number of robust cysts in feces, which are immediately infective. These asymptomatic carriers, especially food handlers, commonly contribute to the spread of disease, as chronic cases and asymptomatic carriers can shed up to 1.5 billion cysts daily. Cysts can be present in sewage and contaminated water, and survive for long periods in aquatic environments while transmission can occur through food and water contaminated by human feces. Cysts are resistant to chlorine at levels used in drinking water supplies, rendering primary disinfection of the majority of drinking water supplies ineffective.


Figure 3: Conceptual tracing back and forth from the Mezquital into Mexico City’s markets through large-scale logistical networks and food supply chains.


Mexico City is fed with what it excretes. To make visible the direct relation between wastewater irrigation in the Mezquital Valley, the production of edible fruits and vegetables and the distribution of this edibles into Mexico City markets and human bodies we need to trace the path back and forth from the Mezquital into Mexico City’s markets. (Figure 3)

Mezquital

Chelsea Kashan (MLA ‘21)

Farmers working in the Mezquital Valley region of Mexico, are dependent on wastewater provided by Mexico City. An accumulation of pipe systems and a difference in sea level of about 400 + meters carries wastewater from drains and sewage systems in Mexico City to the crop fields in the valley, which run in controlled soil irrigation trenches alongside plots.  The farmers profit on Mexico City’s waste, a system that has been in place for over 100 years. The introduction of the government sponsored (CONAGUA) wastewater treatment plant, Atotonilco, poses a threat to farmer livelihood; farmers claim that reducing the nutrients attributed to unfiltered waste, would reduce their crop yield and overall cash earlings. The introduction of Atotonilco has caused a great debate between those working in the Mezquital and health authorities. Health authorities, contrastly claim that using unfiltered wastewater poses major health threats due to the many bacteria that can survive and travel with the waste and have the ability to enter the food market and digestive systems. Epidemiological soils of the Mezquital Valley takes a close look at the actions of the farmer, the body as it moves along site, and the resulting proximity to a variety of pathogens (Figure 1).

As defined by the CDC, Epidemiology is the study of the distribution and determinants of health-related states and events in specified populations. The patient is the community, viewed collectively. To understand the farmers as a collective who are willing to face the threat of disease for maximizing livelihood, profit and tradition, we had to zoom-in to the scale of the bacteria, to understand its morphology, its relation to plant and soil, and to understand the closed loop relationship pathogens have between the Mezquital Valley and Mexico City.

Wastewater is the output of the digestive system, a system that carries both productive nutrient loads and harmful bacteria. We focus our attention on a few of the pathogens of concern in this region: Ascaris Lumbricoides (soil transmitted helminths), Vibrio Cholerae (Cholera), Salmonella Typhi (Typhoid Fever), and Entamoeba Histolytica (Amoeba). These four characters are able to withstand water conditions and have a life beyond when placed on vegetables via irrigation and, when in the uppermost meter of a soil horizon. Vegetables that are eaten raw, hands and the nose are the three most likely characters to transfer these pathogens from the exterior world (crops, soil and dust) to the interior (the digestive tract and bloodstream), where they pose their greatest threat. Framers and their families, who have direct contact with the soil, the water and the raw vegetables face the greatest risk of exposure, but it does not end here; a portion of these vegetables are brought back to markets in Mexico City where the pathogens that traveled attached to the vegetables can reunite with urban digestive tracts and re-enter the wastewater pipe system.



Irrigation district 100-Alfajayucan, in the state of Hidalgo, primarily relies on untreated wastewater irrigation (1) and is the region approved for crop growth of vegetables that are primarily eaten raw, such as lettuce, radish, carrot, and onion. Framers wear boots to prevent water’s contact on the feet. Their hands come into contact with the soil and water, hands feed the mouth, children play in soil and lick their fingers, vegetables with deep wounds not carefully washed are eaten, soil dust gets inhaled: these are all ways in which the bacteria living in soil,  attached to vegetable leaves or roots and in the air, can enter the body. The Ascaris Lumbricoides, for example, can enter the human body by inhaling the eggs present in moving soil dust, through children’s hands that come into contact with the soil or by eating infected vegetables that are not carefully washed or boiled. The worm hatches and grows in the human body, where it ultimately lays new eggs in the digestive tract. When released back into the sewage system, the cycle repeats. Not only is this process in loop, but many of these bacteria favor the climatic conditions in the region and can live in the soil for several months and even years (2). 



Soil is not static, it is a system and accumulation of matter, always exchanging. Understanding soil, and the conditions around it, such as temperature, moisture capacity, pH levels and compaction, allow us to see what other forms of life are capable of inhibiting it, besides our vegetables (Figure 2). These other life forms that inhabit the soil may not be visible, but have a lasting impact that affects human species at large. Understanding our relationship to the soil, and its other inhabitants, can help us make decisions about how we can safely interact with the land. Safe practices such as the use of gloves, or localized, small scale interventions that promote an awareness of the threat of pathogens, may help farmers safely continue using wastewater irrigation. Vegetables are not detached from their soil, they are one until the vegetable is met with clean water. When we consume vegetables, we are nearly consuming its soil, the very character that enables its growth. Our proximity to the soil must be taken with both caution and immense appreciation.




1 Humberto Romero-Alvarez, “Case Study VII* - The Mezquital Valley, Mexico,” WHO, https://www.who.int/water_sanitation_health/resourcesquality/wpccasestudy7.pdf
2 Ascariasis - What Causes Ascariasis? How Does Ascariasis Spread?, Sandra Gomez Gompf and John P. Cunha, https://www.emedicinehealth.com/ascariasis/article_em.htm#what_causes_ascariasis_how_does_ascariasis_spread

Brittany Giunchigliani (MLA I ‘21) & Charles Burke (MArch I + MDes HPDM ‘21)

Tracing the flow of industrial effluents through a series of infrastructural canals is no small task. Research on the distribution, accumulation, infiltration, and deposition of industrial effluents in the Mezquital is fragmented, making it difficult to compose a complete picture of the journey that a byproduct makes as it leaves the home, the textile factory, the storm drain, or the gas station. Therefore, we took a different approach. Rather than tracing the phthalates, volatile compounds, and surfactants merely through their interaction with water, sediment, and soil, we found that these compounds must be traced through their relationship to the narrative and mechanical sources of the Mezquital’s pollution.


        Source: Pinterest              Source: Associated Press

We must first clarify the form of the pollution at its inception: many of the characters we have chosen to highlight and appear in the landscapes and soil profiles above, have been drawn both as a container of and visual expression of their product. We found it essential to illustrate the importance of how these compounds transform along the journey from the factory in Mexico City, along the lined and unlined canals, and into the soils of the Mezquital. From factory to field, their form is altered both passively and actively as they come in contact with different materials, surfaces, sediments, and other pollutants. Each character has been defined through their cultural, historical, political, and morphological relationship to the formation of soil and what we will now conceive as narrative effluent.



As mentioned, the industrial byproducts that make their way from Mexico City to the Mezquital most often begin as a container. The compounds that are discarded as a result of the production of industrial goods and services enter into the wastewater and migrate to the Mezquital through a series of lined and unlined canals before entering the soil. To conceptualize the journey from product to compound to water to soil, we rely on metonyms to produce a narrative structure of each phase. These narrative effluents include the byproducts of Mexico’s robust advertising sector, as well as products of political and capitalist rhetoric that consumed Mexico after the introduction of NAFTA - an agreement among three major stakeholders (USA, Canada, and Mexico) that significantly altered Mexico’s relationship to capitalism, globalization, and industrialization. We also include the mechanical artifacts which embody this capitalist distribution and production: including billboards, industrial washing machines, and cars.



Source: Jstor Daily

Tula Refinery, Sluice Gate, Oil Slick, Surfactant Foam, Petroleum Coke Dust








This particular type of soil formation cycles back in as a political narrative that takes the form of positive publicity from the stakeholders of the products that pollute the Mezquital. The cycle continues - publicity, production, consumption, disposal. The accumulation of these narrative effluents is the main focus of our analysis on soil formation in the Mezquital and how to better understand how the “other side of the pipe” influences the humans and nonhumans that live with these effluents.

Our landscapes above reflect the connection between factory and field, and also emphasize that industry does not only appear on the ‘Mexico City side of the pipe’.


   Source: Google Earth

In the Mezquital, for example, the state-owned Tula Refinery plays a major role in the production of crude oil and gas for Mexico and is a prominent figure in the landscape of the Mezquital. Its network of hidden, often punctured pipes and monumental size contains the product that fuels an important industry in Mexico. This industry has its own stream of narrative effluents that oscillate between product and fluid, publicity and pollution, and travel between Mexico City and the Mezquital through a complex web of culture, politics, history, and morphology. 

In conclusion, the specificity of academic and scientific research must be coupled with an analysis of the narrative elements which play a significant role in the formation of industrial effluents as they make their way into our water and soil. By looking first at the cultural, ideological, and economic representations of the top industries in Mexico, we are able to mine metonymic elements which represent ‘each phase of the pipe.’ This method produces a study of the Mezquital and its soil which resists being categorized as a linear pathway of causal relationships, but is rather more recognizable as a cycle, from factory to field to farmer, and back again.

Mexico City

Jing Yan (MLA ‘20)

Heavy metals such as Cr, Ni, Cu, Zn, Pb and V are naturally occurring elements all around us. According to the World Health Organization (WHO), using a calculation called Significance of intervals of contamination/pollution index (C/P) , concentration of heavy metals over 0.51( mg /kg) is considered to reach the level of  severe contamination (stl). Heavy metal contaminants are polluting air, water and soil by industrial productions, burned fuel, fertilizers, pesticides and even from rocks in Earth’s crust. Plants and crops will absorb these contaminants from air and soil where eventually these heavy metals elements will transmit the elements into animals and humans. Mexico City specifically suffers from heavy metal pollution. The main culprits are leaded petroleum for old car combustors, wastewater irrigation canals and industrial refineries. Not only industrialization causes heavy metal pollutants but traditional mexican pottery also could be hazardous for accidental heavy metal poisoning from food and drink consumption.

Pb (lead) is one of the major pollutants affecting local people and young children are especially vulnerable. Lead poisoning is very dangerous for young children. They absorb lead 4 or 5 times more than adults due to their still developing nerve system. It causes permanent brain damage. Pb comes from a variety of sources, from contaminated food and water or from pregnant mothers to their babies. To trace the sources of heavy metal, we have to draw a picture of the whole system of how heavy metals contaminate people’s digestive system and inter to the bloodstream. One study conducted for a 7-year-old child of a US Embassy official in Mexico City revealed that lead from traditional pottery continanimate drinks and food.3 Traditional pottery is safe unless the glaze – which may contain lead to facilitate the melting of glaze particles – when the fire process of pottery making is not properly done.

Another form of tradition also causes heavy consumption unexpectedly by the local people since they have done it for thousands of years. Historically, during pre-colonial time, chinampa agriculture was a very effective way of wetland farming. The method itself is relatively safe but in1980s Mexico City became more industrialized and urbanized, the economic boom brought the side effect of environmental problems one is higher heavy metals concentration in soil. The emissions of 2.4 million vehicles and 35,000 factories, by the smoke from burning garbage dumps and the dust thrown up by a dry lake bed, a huge blanket of brownish smog covers Mexico City most days. The stories spawned by the city's pollution are graphic - the 11,000 tons of waste material pumped into the atmosphere daily, the doctors who come from all over the world to study new respiratory diseases, the canary that was left in a cage on a downtown street corner and was dead within an hour.1 Car emissions are from leaded gasoline by Mexico’s state owned oil company Pemex. In 1974, although EPA announced to phase out the lead content in gasoline due to environmental hazards. In 1993, 80% of the gas sold by Pemex was still contained Pb. Study shows that there is a higher concentration of Pb along the road and highway infrastructure compared to other parts of Mexico City. Another problem is that there are few vapor recovery nozzles at Pemex station resulting in the escape of noxious fumes into the atmosphere. Fe, Cu, Zn and Pb are detected and higher bacterial counts and heavy metal concentrations reported during the rainy season due to all the pollutants being washed down the drainage system into the irrigation system.2 Rainfall brings all the hazards heavy metal elements into the wastewater canal system and irrigated agriculture areas in Mezquital. Sewage effluent contaminated by industrial pollution eventually is absorbed by crops and animals which ends up into the human digestive system. The matter didn't get better but worse over the years as a result of the NAFTA agreement with the US and Canada. Mexico City became the main manufacturer for steel. Steel production processes and refineries contain Fe, Zn, Ca and Si in the form of simple or mixed oxides, and also Cu, Mn, Ni, Cr, Cd, Pb etc., present in the raw material or introduced as additives. The study of heavy metals in soils around the steel production facility in Smederevo proves that heavy metals are accumulating due to the steel industry.

A consequence of urbanization and growth of  population also causes environmental concerns about waste treatment. According to studies in Newcastle, waste incinerators are likely to be one of a number of sources of contamination that have caused urban soils to have generally greater concentrations of metals than those in rural areas. Cd, Cu, Hg, Pb, and Zn are found in soil that is related to waste incinerators. In Mexico City, a new billion-dollar waste incinerator brewing from 2018 to generate new energy has been under public scrutiny. Growthing job opportunities in Mexico City attract millions of people to migrate to the city which puts more people to expose under the heavy metal contaminations.

The presence of heavy metals in soils is a serious issue due to its residence in food chains, thus destroying the entire ecosystem. As much as organic pollutants can be biodegradable, their biodegradation rate, however, is decreased by the presence of heavy metals in the environment, and this in turn doubles the environmental pollution, that is, organic pollutants and heavy metals thus present.4 There are various ways through which heavy metals present risks to humans, animals, plants and ecosystems as a whole. Such ways include direct ingestion, absorption by plants, food chains, consumption of contaminated water and alteration of soil pH, porosity, colour and its natural chemistry which in turn impact on the soil quality.


Riding, Alan. “PROBLEMS OF MEXICO CITY: WARNING TO THIRD WORLD.” The New York Times. The New York Times, May 15, 1983.
Baker, George. “Does Modernization at Pemex Meet Consumer Needs? Baker, George.” Business Mexico Vol 3, no. Iss 5 (May 4, 1993): 4–47.
Matte, T.d., D. Proops, E. Palazuelos, J. Graef, and M. Hernandez Avila. “Acute High-Dose Lead Exposure from Beverage Contaminated by Traditional Mexican Pottery.” The Lancet 344, no. 8929 (1994): 1064–65. https://doi.org/10.1016/s0140-6736(94)91715-9.
Musilova J, Arvay J, Vollmannova A, Toth T, Tomas J. Environmental contamination by heavy metals in the region with previous mining activity. Bulletin of Environmental Contamination and Toxicology. 2016;97:569-575

Mezquital

Michele Turrini

The mezquital valley is an agricultural region located north of Mexico City which has been irrigated with the urban wastewater since 1890. The use of wastewater for agricultural purposes has been contributing to the fertility of the soil within the region, with a generous amount of organic matter spreading over the fields through each irrigation. On the other hand, irrigation with wastewater is responsible for the accumulation of heavy metals within soil, and it has been a cause of concern for the risk of  entering the food chain with all the associated health problems for animals, plants, bacteria and humans.

Although the presence of metals in soil is a natural occurrence and can be traced back to volcanic activities, some metals are considered harmful in high proportion and non necessary to living organisms for performing their life processes, those include heavy metals such As, Ag, Cd, Hg, Pb. Heavy metals like Pb rarely occur as a consequence of volcanic activity, they are most commonly found in soil due to industrial human activities such as mining and smelting of metalli- ferrous ores, electroplating, gas exhaust, energy and fuel production, fertilizer and pesticide application, and generation of municipal waste and are brought to the Mezquital by wastewater irrigation practices.

The characteristic properties of the soil of the Mezquital are due to past volcanic activity and the consequent accumulation of alluvial pyroclastic material. Its form  is given by the normal faulting of the crust where tensional forces stretched the crust and caused a downwards shift of land establishing the Mezquital graben. A series of layered volcaniclastic tuff deposits (known as Tarango Formation) lay at the base of the Mezquital and are topped by a layer of colluvio-alluvial sediment deposition. This layer can be classified  within the valley as either haplic soil or vertic Phaeozem soil.

The topsoil within the mezquital is mostly composed of clayey soil, with a high proportion of smectite minerals and  with originally little organic matter content which has then been constantly added through  years of wastewater irrigation . In fact the addition of organic matter changed dramatically the soil composition whilst also changing the soil classification,  in the region are classified as Calcaric Phaeozem (50 years irrigation) and Leptic Calcaric Phaeozem (100 years irrigation).

Heavy metals availability in soil is dependent on characteristics such as organic matter, clay, silt, Phosphorus and pH, the latter being the most important factors in the retention and solubility of heavy metals. In fact heavy metals are less available in soil containing high clay percentage (11-60% within the Mezquital) and with a basic pH  which in the Mezquital varies from 6.7 to 8.4, depending on the time of irrigation. Throughout irrigation the heavy metals particles having positive charge, bind with the negatively charged clay particles. Heavy metals are not subject to degradation, this means that less and less binding sites will be available to heavy metals in the future, with possible health risks due to plant intake or heavy metals leakage to underground aquifers.

In addition soils which have been irrigated for more than 100 years tend to have the lowest pH values (slightly acidic),this is due to the loss of the active limestone in the clay caused by intensive irrigation, therefore resulting in higher metal bioavailability. Whilst increasing organic matter content, long term irrigation has also an impact on the quality of organic matter available, which by becoming more hydrophilic tends to reduce its capacity of restricting heavy metals movement.

All those factors play a fundamental role in the future of the Mezquital, essentially it is a matter of time before the clay particles will exhaust all the available binding sites making the heavy metals available for plant intake and with the reduction in organic matter quality the possibility to restrict heavy metals movement will thin out, making possible the pollution of underground aquifer due to the leakage of heavy metals from the topsoil.




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E.R, Orhue & Uzu, Frank. (2011). Fate of some heavy metals in soils: a review. Journal of Applied and Natural Science. 3. 131-138. https://doi.org/10.31018/jans.v3i1.171.
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Dalkmann, Philipp, Elisha Willaschek, Henning Schiedung, Ludger Bornemann, Christina Siebe, and Jan Siemens. 2014. "Long-Term Wastewater Irrigation Reduces Sulfamethoxazole Sorption, but Not Ciprofloxacin Binding, in Mexican Soils." Journal of Environmental Quality 43 (3) (May): 964-970. http://search.proquest.com.ezp-prod1.hul.harvard.edu/docview/1549961361?accountid=11311.

Mexico City

Olivia So (MLA I  ‘21)

Mexico City’s sewer system, servicing 18 million residents, is connected with the irrigation channels of the Mezquital Valley’s agriculture fields. The wastewater generated possesses the excretion of drugs, in its unaltered form or modified by the human body. A study examining the wastewater of the “Central Emitter” identified ibuprofen, naproxen, and diclofenac, alongside Metformin and Carbamazepine, throughout the irrigation channels in the Mezquital Valley. Within the urban wastewater in Rio San Ángel, a neighborhood in Mexico City, paracetamol, salicylic acid, sulfamethoxazole, and ofloxacin was found in the wastewater. To understand the concentration of pharmaceuticals found within the wastewater, we must understand how Mexico City's urban landscape influences public health, nutrition, and the resultant wastewater composition.

Neighborhoods throughout Mexico City do not have equal access to water as the city has 8,000 miles of failing pipes that waste 40% of the water running through it or is illegally stolen. Because residents’ taps may only release water once a week or less, and when it does the quality is questionable, residents store and ration water in buckets or rooftop tinaco (water tank) when pipas, or large water trucks, deliver water.


Haner, Josh, photographer. “[A pipa in the San Andrés Totoltepec neighborhood.]” Photograph. From Kimmelman, Michael. “Mexico City, Parched and Sinking, Faces a Water Crisis.” The New York Times, The New York Times, 17 Feb. 2017.

This unreliable access to drinkable water contributes to the consumption of packaged drinks, especially sweetened beverages.This is a complex issue as some portions of the population also prefer sweetened beverages over plain water as reported by Elizabeth Roberts, especially when sweetened beverages were cheaper than bottled water until 2014. The tax on sugar-sweetened beverages did decrease purchases, however longer term studies need to exist to understand whether this trend continues or if consumers substitute to cheaper brands or untaxed foods and beverages, not changing nutrition consumption. The prevalence of sweetened beverages and packaged foods contributes to the obesity rates and sugar intake among urban residents. It is not that “food deserts” exist, as fresh fruits and vegetables are available throughout most neighborhoods in Mexico City, rather “food swamps” where these calorie dense foods greatly affect the nutrition available. In Bridle-Fitzpatrick’s study, low-income and middle-income neighborhoods possessed higher access to small vendors and convenience stores that sell junk food and beverages.

Mexico is well-documented with the highest obesity and overweight rates in the world and diabetes prevalence at 14.4% in 2006, with almost half the cases undiagnosed. Rafael Meza states that “1 in 3 to 1 in 2 individuals [could be] getting a diabetes diagnosis in their lifetime.” In order to treat these chronic illnesses, purchasing medication in Mexico is both easier and cheaper than in the United States. Pharmacies are not only abundant in major cities but also most medications do not require a prescription, excluding antibiotics. A study completed by Núria Homedes and Antonio Ugalde examines pharmacies on the Mexico-United States border and the Mexican tendency to self-prescribe. Their study also found that “antibiotics were frequently used inappropriately, regardless of whether they had been prescribed by a physician” and that many workers within pharmacies are not formally trained and rely on medication information obtained from promoters of particular brands. A common model for pharmacies is to partner with an adjacent physician, allowing for ease in obtaining a prescription if necessary. This demonstrates the potential unethical issue of doctors prescribing more expensive medications to the pharmacy they are in contract with. The ease of pharmaceutical access and the tendency for Mexicans to self-medicate leads to excess consumption that will end up in waste water in the end.

The unique relationships between water access, nutrition, and pharmaceuticals in Mexico City contributes to the composition of the wastewater irrigating the fields in the Mezquital Valley. However it is not just a matter of what Mexico City residents are ingesting, but also the failing water infrastructure, a broader network of the nutrition that is available to them, and the chronic illnesses affecting the entire nation.



Bridle-Fitzpatrick, Susan. "Food Deserts or Food Swamps?: A Mixed-methods Study of Local Food Environments in a Mexican City." Social Science & Medicine 142 (2015): 202-13. https://doi.org/10.1016/j.socscimed.2015.08.010

Calderón, Aarón, Mónica Meraz, and Araceli Tomasini. "Pharmaceuticals Present in Urban and Hospital Wastewaters in Mexico City." Journal of Water Chemistry and Technology 41, no. 2 (2019): 105-12. https://doi.org/10.3103/S1063455X19020073

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Homedes, Nuria & Ugalde, Antonio. (2012). “Mexican Pharmacies and Antibiotic Consumption at the US-Mexico Border.” Southern Med Review. 5. 9-19. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3606934/

Kimmelman, Michael. “Mexico City, Parched and Sinking, Faces a Water Crisis.” The New York Times, The New York Times, 17 Feb. 2017. https://www.nytimes.com/interactive/2017/02/17/world/americas/mexico-city-sinking.html

Meza, Rafael, Tonatiuh Barrientos-Gutierrez, Rosalba Rojas-Martinez, Nancy Reynoso-Noverón, Lina Sofia Palacio-Mejia, Eduardo Lazcano-Ponce, and Mauricio Hernández-Ávila. "Burden of Type 2 Diabetes in Mexico: Past, Current and Future Prevalence and Incidence Rates." Preventive Medicine 81 (2015): 445-50. https://dx.doi.org/10.1016%2Fj.ypmed.2015.10.015

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Mezquital

Kymberly Ware (MLA II  ‘21)

The Mezquital Valley is a microcosm of Mexico’s economic, ecological, and public health landscape in the wake of the North American Free Trade Agreement. From land privatization to the use of wastewater irrigation that is highly concentrated with anti-diabetic, anticonvulsant drugs and their byproducts, this ground has been witness to the beginning and end of a food system that has fueled a public health crisis.

Policy changes at the close of the twentieth century marked the beginning of the ecological shift for this landscape. Before the passage of the 27th amendment to the Constitution of Mexico in the late 1980s, the country’s agricultural land ownership primarily took the form of communally based ejidos. Since the establishment of the ejido system in 1917, farmers had autonomy over their cultivation practices and were able to produce economically viable crops while creating seed banks to strengthen the genetic resources from which new cultivars could be bred. For example, farmers had developed diverse varieties of rain-fed maize (Zea mays), or corn, that could be used for multiple outputs in addition to consumption including handicraft, fuel, building material and medicinal production. Following the passage of the 27th amendment, the Mexican agricultural lands were parceled to open up the land for possible private ownership. When NAFTA exponentially increased the amount of corn produced in the United States and exported to Mexico, the economic viability of small-scale domestic corn production fell, forcing many farmers to sell their land to private agribusinesses like ConAgra to raise large scale commercial mono-crops of irrigated corn. Some ejido parcels remain in Mexico, and the Mezquital Valley has some of the largest ejidos still left in the country.

The corn produced in the intensively managed, large-scale system in both Mexico and the United States is primarily dent and sweet corn. While sweet corn is used for consumption, the output of dent corn is largely used for livestock feed or to produce processed goods such as high fructose corn syrup (HFCS). Depressed prices and overproduction of corn post-NAFTA exacerbated the proliferation of cheap highly processed food products that depend on HFCS and hydrogenated vegetable oil. The increased availability of these byproducts like sugar-sweetened beverages, chips, and other calorie-dense, nutrient-deficient foods has led to increased obesity rates in Mexico. The pharmaceuticals found in the wastewater, soils and groundwater of the Mezquital Valley tell this story of the food system and public health issues of Mexico City.

Medications used to treat chronic diseases associated with obesity are the most concentrated in all levels of the wastewater irrigation system of the Mezquital. Of the dense pharmaceutical cocktail that enters into the region’s irrigation canals every day, the anti-diabetic medication Metformin and anticonvulsant drug Carbamazepine are the most persistent—showing in high concentrations in deeper levels of the soils, reaching groundwater, recirculating through drinking wells and even translocating to the tissue of certain crops.

Deuschle, L. “Landrace: Zea Mays and the NAFTA Landscape.”Scapegoat. Issue 6 (2014)

Anchoring the corn and facilitating the movement and concentration of pharmaceuticals, the clay soils of the Mezquital are an archive of an economically, culturally and ecologically disrupted landscape in the wake of trade liberalization. In this reframing of soil classification, we can begin to understand soils as a record of how humans not only interact with the ground but are impacted by its outputs as a result of those interactions.



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Eggen, T. and Cathrine Lillo, “Antidiabetic II Drug Metformin in Plants: Uptake and Translocation to Edible Parts of Cereals, Oily Seeds, Beans, Tomato, Squash, Carrots, and Potatoes.” Journal of Agricultural and Food Chemistry. No. 60. (2012): 6926-6935.

Perramond, Eric P. “The Rise, Fall and Reconfiguration of the Mexican Ejido.” Geographical Review. Vol. 98, No. 3 (2008): 356-71.

Mexico City

Haoyu Zhao (MLA I ‘20)

The project investigates the chemosphere in the soil of Mezquita valley and its connection to Mexico City. Each day, a large number of pharmaceuticals and their metabolites are released to the city’s sewer system and drained to the Mezquita valley, where the untreated water directly irrigates the agricultural soil. The research understood the material flows of pharmaceutical production, consumption, and the environmental fate of several significant pharmaceuticals. By representing the soil in the language of pharmaceuticals breakdown products, we unraveled the dynamic landscape of health, economy, and political struggle in Mexico City and its consequence in the agriculture in Mezquital valley.

In Lesser’s investigation on 218 organic contaminants found in Mezquital Valley, Metformine, Caffeine, Cocaine, and its metabolites, and DEET has been found most prominent in the soil. The four pharmaceutical reveal a direct connection to the consumption of pharmaceuticals in Mexico City.

Metformin is a pharmaceutical targeted for type 2 diabetes, the recent growing population suffering from type 2 diabetes in Mexico City explained the wide distribution of these chemicals in the soil of Mezquital Valley. However, Galega officinalis, the base for metformin extraction, is a typical temperate plant thrives in Europe and Asia. The consumption and normalization of Metformin stimulate the oversea imports of Metformin and create a landscape of globalization that the chemical residues in the agricultural soil are alien to its native chemosphere. Metformin enters the aquatic environment through human waste, suggesting domestic bathroom, and toilet and the blackwater is the major venue where the chemicals exposed to the environment. Recent studies have also suggested that Metformin, although resistant to the human metabolic system, once released to the water, can be transformed into Guanylurea in the chlorination process of water treatment plants. Guanylurea is a chemical that is more resistant to biodegradation, and few studies have been able to understand its environmental impact.

Cocaine and its metabolite, Benzoylecgonine, also reveals the drug abuse problem in Mexico City. The use of cocaine and other drugs has been partly attributed to the drug trafficking activities in Mexico. Cocaine consumption first rises in the 90s and stay growing afterward, and the population related to cocaine use varied in ages and income levels. Even only makes up a little portion of the total organic contaminant detected in the water of Mezquital Valley, cocaine and its environmental fate is better understood than other pharmaceuticals due to its criminal nature. Similar to Metformin, Cocaine and Benzoylecgonine enters the environment through human waste.

For DEET and Caffeine, both of the drugs are subjects to daily usage. Caffeine enters the environment through urine. DEET, as a widely used insect and acarid repellent, it enters the aquatic surface through everyday human activities such as showering or bathing, and laundering of clothes has been applied with DEET.


Lesser, Luis E, Abrahan Mora, Cristina Moreau, Jürgen Mahlknecht, Arturo Hernández-Antonio, Aldo I Ramírez, and Héctor Barrios-Piña. "Survey of 218 Organic Contaminants in Groundwater Derived from the World's Largest Untreated Wastewater Irrigation System: Mezquital Valley, Mexico." Chemosphere 198 (2018): 510-21.

“Galega Officinalis.” Wikipedia. Wikimedia Foundation, April 14, 2020. https://en.wikipedia.org/wiki/Galega_officinalis.
Scheurer, Marco, Amandine Michel, Heinz-Jürgen Brauch, Wolfgang Ruck, and Frank Sacher. "Occurrence and Fate of the Antidiabetic Drug Metformin and Its Metabolite Guanylurea in the Environment and during Drinking Water Treatment." Water Research 46, no. 15 (2012): 4790-802.
Brouwer, Kimberly C, Patricia Case, Rebeca Ramos, Carlos Magis-Rodríguez, Jesus Bucardo, Thomas L Patterson, and Steffanie A Strathdee. "Trends in Production, Trafficking, and Consumption of Methamphetamine and Cocaine in Mexico." Substance Use & Misuse 41, no. 5 (2006): 707-27.

Zooplankton, Needle, Toilet, Tire, Stethoscope, Lilac



Mezquital

Lu Dai (MLA I AP  ‘20)

The project investigates the chemosphere in the soil of Mezquita valley and its connection to Mexico City. Each day, a large number of pharmaceuticals and their metabolites are released to the city’s sewer system and drained to the Mezquita valley, where the untreated water directly irrigates the agricultural soil. The research understood the material flows of pharmaceutical production, consumption, and the environmental fate of several significant pharmaceuticals. By representing the soil in the language of pharmaceuticals breakdown products, we unraveled the dynamic landscape of health, economy, and political struggle in Mexico City and its consequence in the agriculture in Mezquital valley.

Through the sewage pipe, a large number of pharmaceuticals flow from mexico city to mezquital valley, but only 70 types of pharmaceuticals are detected in the wastewater and 23 types in underground water, which means some pharmaceuticals break down during the transportation process or degrade in the soil.

Among the pharmaceuticals we find in Mezquital Valley, metformin and caffeine are the two most frequently detected while in underground water, a large amount of benzoylecgonine (the metabolite of cocaine) and deet have been found. For metformin and caffeine, they have been highly degraded in soils by bacterias and scientists prove that the break down process are affected by the moisture and temperature in the soil. 1,7-dimethylxanthine(the metabolite of caffeine) and guanyluree(the metabolite of metformin) will stay stable in soil and slowly be mineralized to molecules. However, for benzoylecgonine or deet,since they are stable in soil so they can reach groundwater and pose threat for human drinking water. Furthermore, deet has been proved to be toxic for some fresh water fish like rainbow trout and tilapia, and it has shown negative impact for freshwater zooplankton. Benzoylecgonine on the other hand, are affecting the cultivation of beans and aloes in Mezquital Valley.

These well known metabolisms are only small part of story of pharmaceuticals in the wastewater or Mezquital Valley. We can only test for what we made in our laboratories but cannot identify the unknown chemicals and the breakdown process of all the components.Current research focuses more on the first phase of metabolism but not the second or further degradation. Moreover, the breakdown products which enter the underground water will spread through the water flow that we are unable to track its distribution. Still, how these pharmaceuticals will transform and affect the ecosystem or human health in Mezquital Valley remains mostly undiscovered.