Taking the trash out of our homes can make it feel as though the problem ends once the garbage truck drives away with it. Yet some of our waste ends up on streets, in vacant lots and in bodies of water, where it can remain for months or even become part of more complex systems, such as rivers that flow into oceans.

“Our waste stays behind, even though we think it magically disappears when we put it in the trash,” says Sheila Quintana, a researcher at Tecnológico de Monterrey’s Water Center for Latin America and the Caribbean.

A recent study examined this problem in Arroyo Seco, an urban stream in the municipality of Monterrey, and explored whether the work of people known as pepenadores—informal waste pickers who recover recyclable materials—could be used to clean it up.

Globally, waste is a large-scale environmental and public health problem. In 2022, approximately 2.56 billion metric tons of waste were generated worldwide.

The problem is not only how much waste we produce, but what happens to it afterward. Collection, recovery and final disposal systems are failing to manage everything we generate.

In low- and middle-income countries such as Mexico, collection services cover only a fraction of the waste generated, and much of it ends up in open dumps, is burned or makes its way into bodies of water.

“We need to remember that Monterrey is 200 kilometers from the Rio Grande at the U.S.-Mexico border, and that whatever falls into our streams eventually reaches the Gulf of Mexico and the Atlantic,” says Elfide Mariela Rivas, a research professor at the School of Architecture, Art, and Design (EAAD).

Rivas, Quintana, Andrea Martínez and Sebastián Quibrera, fellows at EAAD, worked on the study, which seeks to propose solutions from a circular economy perspective.

What Waste Pickers Tecover—and what Remains in the Stream

To explore the possibility of using waste pickers’ work to clean up Arroyo Seco, the team conducted fieldwork between May and December 2022. The researchers observed the activities of 49 waste pickers, documented their routes and the materials they collected, conducted interviews, and analyzed the composition of the waste using tools such as the Marine Debris Tracker and the Circularity Assessment Protocol.

During the cleanup efforts, more than 4.3 metric tons of municipal solid waste and approximately 87 metric tons of debris were removed from the banks of the stream. However, only 123.4 kilograms consisted of recoverable materials.

“There was virtually no PET plastic, metal or cans in the stream,” Rivas recalls.

Based on the team’s observations, this makes sense: waste pickers primarily look for materials they can sell, such as PET plastic, cardboard and metal, while leaving behind waste with little commercial value, including textiles, furniture and construction debris.

This led the team to realize that Arroyo Seco cannot be cleaned up simply by relying on the work of waste pickers, because the materials with the greatest economic value are precisely the ones they remove before they reach the stream.

The problem becomes even more complex when it comes to construction waste. During the fieldwork, the researchers observed instances of construction debris being illegally dumped into bodies of water.

“There is a whole clandestine side to this. You see that the companies responsible for ensuring this debris is taken to state-designated disposal sites simply do not do it,” Rivas emphasizes.

This reveals that pollution is tied not only to residents’ disposal habits, but also to failures in the oversight and management of different types of waste.

Urban Recyclers are also Part of the Solution

The study also argues that the work of waste pickers should be recognized because it is part of a materials recovery chain that cities need and that, elsewhere, has been incorporated into formal recycling systems.

“What if we called them something else? What if we called them urban recyclers? There is a great deal of stigma attached to the word pepenador,” Martínez says.

In some parts of Mexico, mechanisms such as identification cards, collection centers and specific rules are in place to recognize and organize this work. In Nuevo León, however, restrictions and regulatory gaps remain.

“In some places, such as San Pedro, this work has already been unionized, while in others it has not,” Quibrera says.

The issue is also shaped by stigma. The team found that public perceptions of the occupation can change when there is some degree of organization or formal recognition. However, formalization is not straightforward, either: some workers may earn more by operating informally, while the prices of recyclable materials fluctuate, leaving much of the economic benefit in the hands of intermediaries.

For this reason, the researchers propose integrating urban recyclers into circular economy strategies, improving safety conditions and creating mechanisms that make it economically viable to recover materials that currently have too little value.

They also recommend strengthening infrastructure and oversight to prevent waste—especially construction debris—from reaching bodies of water.

When Waste Crosses Borders

Arroyo Seco’s connection to other rivers in the Rio Grande basin adds another dimension to the problem.

“Understanding that watersheds extend beyond municipal, state and national borders is crucial,” Rivas says.

The researchers therefore believe waste management must be considered beyond the boundaries of a municipality—or even a country.

For the team, the work begins at home: with how we sort our trash, what we choose to throw away, and what we reuse or recycle.

The study thus shows that the waste problem begins long before an item reaches the stream. It also raises a question about who recovers the materials we discard and under what conditions.

“Government agencies—the state, the municipality and everyone responsible for waste—can no longer keep up,” Quintana says. Looking beyond the solutions already proposed is not merely a suggestion, but a necessity.

Recognizing the work of waste pickers and improving the way waste is managed are necessary steps toward a circular economy and greater environmental justice.

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