Global Trash Network Analysis Reveals Where the Most Hazardous Are Piling Up

Researchers from the IFISC institute have identified 28 countries at high risk of waste congestion, with consequent risks for health and the environment. Among them are Mexico, India and Uzbekistan, which import large quantities of these products considered dangerous. China, Mozambique, Senegal and Afghanistan are those with the greatest chemical contamination produced by garbage.

Each year, between 7,000 and 10,000 million tonnes of waste are produced worldwide, including between 300 and 500 million of hazardous waste, ie toxic, flammable, explosive, corrosive or biohazardous waste. Countries trade with them and in the last 30 years the volume of dangerous has increased by 500%.

Some of this remnant does not stay in its country of origin and travels through a global network of waste, the global waste network, to be dealt with elsewhere. There are economic incentives to market them, however, importing countries often face management and environmental health issues. In some, congestion problems are already appearing, when the quantity of this waste exceeds the quantity of treatment.

Now researchers from the Institute of Interdisciplinary Physics and Complex Systems (IFISC, a joint center of CSIC and the University of the Balearic Islands), have used data from 2001 to 2019 (excluding 2010) to track the trade in 108 categories of hazardous waste. between countries and have developed a mathematical framework to model global waste network.

The results of the study, published in the journal Nature Communicationidentified the net exporters and importers of waste and the countries at greatest risk of congestion, by identifying when they reach their carrying capacity and become saturated with a certain type of waste.

In this way, the authors identified 28 countries that present a high risk of waste congestion, which could lead to improper handling of the material and possible contamination affecting both the environment and human health. This includes Mexico, India and Uzbekistan, which import large volumes of hazardous waste.

The data also shows that countries like Germany, France and the United States have moved from more balanced waste streams to predominant net exporters, with China becoming the top net exporter of hazardous materials.

The countries most polluted by chemical waste are China, Mozambique, Senegal and Afghanistan, and four European countries are at medium risk: Ukraine, Bosnia, Belgium and Bulgaria.

The global trade in waste, “on the one hand consists in disposing of leftovers at a lower cost in the case of countries exporting garbage, and on the other hand, in having easy access to the materials collected by recycling these wastes, in the case of countries importing countries. This is why the global waste network it is a directional and weighted network, i.e. the waste travels from country A to country B, but not in the other direction or in the same quantity as from A to C, for example”, explains Ernesto Estrada, the IFISC researcher who is leading the work.

This feature is evident in the large asymmetry that exists in the import and export of hazardous wastes between developed countries (usually exporters) and developing countries (usually importers).

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Study methodology

To carry out the research, the authors defined a different network for each of the types of waste analyzed from the database. Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal (BaC) and compared with the individual capacity of each country to manage them during the years analysed.

Waste treatment capacity is not the same for all countries, and many of them run the risk of becoming congested, i.e. importing more waste than they are capable of. manage without compromising the environment. To quantify this, the researchers used the Environmental performance index (EPI), a classification that indicates which countries best respond to the environmental challenges each nation faces and provides information on the ability to manage different types of waste.

This index, as well as the structure of the global waste network, identifies countries at high risk of rapid congestion if their PPE does not match the amount of hazardous waste they import. Of the 57 countries that are in this high-risk situation, 29 of them are in Africa, 16 in Asia, 5 in America, 4 in Europe and 3 in Oceania.

The impact of these countries at high risk of congestion can be verified by analyzing chemical fingerprints or chemical fingerprintschemical elements generated by waste that leave quantifiable residues in the environment in the form of heavy metals, volatile organic compounds or persistent organic pollutants.

Spain is in the safe zone, like most European countries, because its infrastructure capabilities and environmental trajectory mean that the waste stream in and out of it does not pose a high risk of environmental impact.“, notes Estrada, “although being in this zone does not mean that a country cannot move to high risk if its waste imports increase beyond its treatment capacities.”.

Among the 28 countries most at risk, there is none from Europe. However, four European countries are in a medium risk situation: Ukraine (the period studied does not include the impact of the war), Bosnia and, although to a lesser extent, Belgium and Bulgaria.

As for the structure of global waste networkthe study claims that the density of connections has decreased between 2001 and 2019, in addition to observing that many countries are becoming either exclusively importers of waste (such as Mexico) or exclusively exporters (such as China).

The authors say their study will help assess global waste scenarios and the impacts that certain policy changes might have, for example due to the pandemic or import bans. They also point out that their work opens the door to more effective management of hazardous waste, which allows the implementation of measures to ensure better control.


Johann H. Martínez, Sergi Romero, José J. Ramasco and Ernesto Estrada. “The Global Web of Waste”. Nature Communication, 2022 to be determined. DOI: 10.1038/s41467-022-28810-x

Source: CSIC/IFISC/Nature

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