52 million tons of plastic slips into the environment every year

An estimated 52 million metric tons of plastic is spilling uncontrolled into the environment every year, according to a new study (Nature 2024, DOI: 10.1038/s41586-024-07758-6).

By weight, 43% of this waste ends up as litter. People dispose of the other 57% by burning it in waste pits or by other unregulated methods that lack environmental controls. This uncontrolled waste accounted for over 20% of all of the plastic waste generated from municipal sources in 2020.

The researchers, at the University of Leeds, used a machine learning model to find that the amount of such plastic pollution was highest in southern and southeast Asia and sub-Saharan Africa. According to this model, the world’s biggest emitter of plastic pollution was India at about 9.3 million metric tons of plastic pollution per year. India is also the world’s most populous country, with around 1.43 billion people in 2023, according to the World Bank. In lower-income countries, uncollected trash tends to be the biggest source of plastic pollution, while littering is often the main source in higher-income countries.

“The global plastic pollution crisis is the most important emergent global challenge of our times,” says Costas Velis, an environmental engineer at Leeds and one of the authors of the paper. To solve the problem, policymakers need to know how much plastic pollution is generated, where it comes from, and where it goes, he says.

Velis and coworkers Ed Cook and Joshua Cottom created a model to answer this question. They looked at plastic that’s disposed outside of regulated channels such as city-run landfills or recycling centers. This includes litter, uncollected waste from areas that don’t have regulated trash or recycling pickup, and plastic that recycling centers can’t process.

“We took the data from about 500 to 600 municipalities, which represent around 12% of the global population, and we extrapolated that to just over 50,000 municipalities,” Cook says. From this city-to-globe approach, the researchers were able to pinpoint areas where government action on plastic pollution is most needed.

“From our model, we think that for around 1.2 billion people worldwide, their waste just isn’t collected,” Cook says. And if your waste isn’t collected, what would you do with it? People in this situation tend to burn it, he says.

The high amounts of plastic pollution in lower-income countries are fundamentally associated with the failure of governments to provide waste collection services to people, Velis says. “And most of it happens in the least affluent places in the world and in the least affluent communities in the world,” he says. “Less-privileged people are those who are really affected by this lack of services.”

This is one reason why India produces so much plastic pollution, the authors say. “The rate of waste collection in India is very low, particularly in some of the rural areas,” Cook says. Past models have put China at the top of this list, but many of them don’t include open burning as a fate of plastic waste, Velis says. “A lot of it is happening in India,” he says. In addition, the Leeds researchers used data that reflects how much the population of India has grown, Velis says.

David Wilson, an expert in resource and waste management at Imperial College London who was not involved in the research, says the information fills a gap. “This work is important because it is the first comprehensive attempt to build an inventory based on an understanding of the different mechanisms by which wastes leak into the environment,” and to add them up from the local to the global level, he says.

The model confirms some things scientists and policymakers have long suspected, Velis says. But now they have quantifiable evidence for the size of the plastic pollution problem and the extent of open burning, he says.

The plastic pollution problem will not be solved unless policymakers prioritize plastic policies at the local and national levels and ensure they are monitored and enforced, Velis says. This model gives a baseline for plastic pollution, allowing policymakers to focus attention and resources where they’re needed the most, he says.