As we all know, our daily activities, from production to consumption, have resulted in a rapid increase in waste generation quantities and composition complexity. This combined with the lack of proper waste management systems threatens terrestrial and aquatic ecosystems as well as human health. If current conditions persist, the negative consequences will be further exacerbated. Currently, the debate on waste leakage into aquatic environments is centered mainly on plastic waste, and measures are being internationally discussed to tackle the problem from plastic production to its end-of-life.

However, the waste crisis extends far beyond plastic pollution. Although initiatives to stop plastics from entering the oceans exist, without appropriate waste management systems it is impossible to stop the initial leakage of waste into our ecosystems. A systemic approach integrating political, technical, and behavioral solutions is urgently needed. These solutions must be inclusive and ensure that benefits are equitably shared among all stakeholders. So, if we need to intervene in the waste sector to tackle plastic pollution, why focus on a single stream when we can tackle the problem comprehensively for more types of waste? Do we want to repeat the same process with every single waste stream? Are we aware of all the co-benefits widespread adoption of sustainable waste management systems holds?

In this study, we assessed the benefits of improving the entire waste management system to reduce waste leakage into lakes, rivers, and coastal areas by considering various possible future scenarios. The scenarios represent the following five world developments: 1. A sustainable world in which consumption is reduced, 2. Business as Usual, 3. Regional Rivalry, 4. Inequality, and 5. A world based on fossil fuels and high consumption patterns.   

Our results show that countries with the highest amounts of uncollected waste do not necessarily coincide with those having the highest waste leakage into aquatic environments. The majority (70%) of potential waste leakage into aquatic environments occurs in China, India, South Asia and Africa. We demonstrate that adopting circular waste management systems can be an effective mitigation strategy to prevent waste from entering aquatic ecosystems. These measures include waste reduction, source-separated waste collection, landfill diversion by increasing recycling, composting, anaerobic digestion, and incineration of waste only as a last resort. Implementing such a system will deliver additional benefits by reducing greenhouse gas and air pollutant emissions and supporting the transformation from a linear to a circular economy. However, we found that even in a scenario representing a sustainable world where technical, social, and financial barriers are overcome, and public awareness and participation in reducing, reusing, and recycling waste are high, fully eliminating waste leakage by 2030 is unfeasible. The analysis also shows that universal waste collection remains essential even in a world where measures to reduce waste are implemented.

The outcomes of this study provide science-based evidence to support the development of a new treaty aimed at creating a legally binding instrument to end plastic pollution and highlight the importance of improving waste management systems globally.