A group of researchers from IFISC (UIB-CSIC) led by Dr. Ernesto Estrada, has identified the list of countries with the highest risk of saturating their waste management capacity. The article, published in Nature Communications, has reconstructed the world-wide waste web, a set of global exchange networks between countries that import and export waste. The researchers defined a separate web for each of the waste types analyzed using data from the BaC (Basel Convention on the Control of Transboundary Movement of Hazardous Wastes and their Disposal) online database and matched it with each country's individual capacity to manage such waste.
Between 7 and 10 billion tons of waste are produced annually worldwide. This includes between 300 and 500 million tons of hazardous waste, whether corrosive, flammable or toxic. Some of this waste does not stay in its country of origin and travels through the world-wide waste web to be processed elsewhere. This is done, on the one hand, to dispose of the waste more economically in the case of waste exporting countries, and on the other hand, to have easy access to materials collected by recycling these wastes in the case of waste importing countries. That is why the world-wide waste web is a directional and weighted network, i.e., waste travels from country A to B, but not the other way around or in the same quantity as from A to C, for example. This characteristic is evident in the great asymmetry in the import and export of hazardous waste between developed (typically exporting) and developing (typically importing) countries.
However, the capacity to process these wastes 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 able to manage without compromising the environment. To quantify this, the researchers used the Enviromental Performance Index (EPI), a ranking that indicates "which countries are best addressing the environmental challenges facing each nation" and provides information on capacity to manage different types of waste. This index, together with the structure of the world-wide waste web, makes it possible to identify those countries with a high risk of quickly becoming congested if their EPI does not match the amount of hazardous waste they import. Of the 57 countries that are at high risk, 29 of them are in Africa, 16 in Asia, 5 in the Americas, 4 in Europe and 3 in Oceania. The impact of these countries at high risk of congestion can be verified by analyzing chemical fingerprints, chemical elements generated by waste that leave quantifiable traces in the environment in the form of heavy metals, volatile organic compounds or persistent organic pollutants.
Regarding the structure of the world-wide waste web, the study states that the density of connections has decreased between 2001 and 2019, in addition to observing that many countries are becoming either exclusively waste importers (such as Mexico) or exclusively exporters (such as China).
The authors conclude that this study opens the door to more efficient hazardous waste management and allows the implementation of measures to ensure better control of hazardous waste.
Johann H. Martínez, Sergi Romero, José J. Ramasco, and Ernesto Estrada. The world-wide waste web. Nat. Comm. DOI: 10.1038/s41467-022-28810-x