Royda Joseph, a 32-year-old mother of three lives in a community next to the PuguKinyamwezi dump in Tanzania. “The dump is on fire every two days,” Royda told the UK NGO TearFund. “Sometimes, when it is on fire, the smoke is so dark and huge that you can’t see the person in front of you or the house next to you. Because of that smoke I get breathing problems and coughing, and eye problems too. The kids also get a lot of breathing problems: they cough a lot.”

In developing cities, from Lagos, to Cairo and New Dheli, air pollution generated by the burning of plastic waste is a daily reality – a 30 metric tonne a year reality according to a new Nature study from researchers at the University of Leeds in the UK. The study found that some 52 metric tons of plastic waste are improperly disposed of every year. And of that, some 57% of that waste is burned openly, launching a slew of toxic chemicals into the air, and disproportionately affecting communities in the Global South. 

The findings have particular meaning for health, which are not well understood. The resulting smoke is a complex mixture of chemicals – including known or suspected carcinogens like bisphenols, phthalates, and dioxins, and a less-understood threat, microplastics. 

The Nature study comes as negotiators gear up for the next round of discussions over an international treaty  on plastic pollution in November in Busan, South Korea. So far, the focus of negotiations has mainly been on the disposal of plastics in landfills and waterways – and not health-harmful air pollution exposures from incineration. 

Model estimated improper waste disposal across 50,000 municipalities worldwide

Using artificial intelligence to model and estimate plastic waste across 50,000 municipalities worldwide, the researchers identified Sub-Saharan Africa, South Asia, and South-East Asia as “hotspots” for improperly burned or disposed of plastics. India, followed by Nigeria and Indonesia, tops the list as the largest pollution emitter, producing one -fifth of global plastic pollution at 9.3 metric tonnes of plastic waste. China, Russia, Pakistan, Cambodia, and Brazil also ranked as high pollution producers.  Some 1.5 billion of the world’s 8 billion people, mainly in the Global South, live without any waste collection services or with highly inadequate services. 

As a result, low- and middle-income countries in the Global South emit roughly two-thirds of the world’s unmanaged plastic waste, defined as un-contained debris that winds up in open landfills, along fields and roadsides, or in waterways – or conversely as incinerated microplastics. Altogether, uncollected waste in lower-middle income countries accounts for 38% of total global plastics incineration emissions and 51% of plastic debris. 

While in developed countries, plastics incineration occurs in high-temperature, high-tech industrial burning sites, with controlled emissions release, in developing countries most of this unmanaged plastics waste is burned in open pits or piles in neighborhoods and streets of cities, towns and villages, or on their periphery, the study notes.

Burning plastics release microplastics, other hazardous chemicals

The resulting smoke is a complex mixture of chemicals – including known or suspected carcinogens like bisphenols, phthalates, and dioxins, and a less-understood threat, microplastics. 

The health effects can be severe, Gauri Sanjeev Pathak, an Associate Professor at Aarhus University in Denmark, told Health Policy Watch. 

“Such emissions have been tied to cancer, respiratory problems, immunological issues, and birth defects, among a host of other human and planetary health issues,” she said. 

“Both open burning and degradation of plastics entering the environment as unmanaged solid waste can produce microplastics,” added Katrina Smith Korfmacher, Professor of Environmental Medicine at the University of Rochester and co-director of the Lake Ontario MicroPlastics center. “Open burning poses well-known threats to human health,” she said.

One study estimated that humans may inhale up to 22 million particles of micro- and nanoplastics annually. Inhaling these pollutants can cause breathing problems, exacerbate existing respiratory conditions, and contribute to air pollution-related diseases.

Gaps in knowledge about the health effects of plastics air pollution exposures

Despite the growing number of studies on the health risks of microplastics, the World Health Organization (WHO) notes that “many gaps remain in the current scientific knowledge of the health impacts of different types of plastics and added chemicals and their breakdown in the environment,” in a December 2023 report to the WHO Executive Board

Along with the direct exposures to humans from incineration smoke, tiny particles of carcinogenic chemicals like dioxins and furans, eventually settle on cropland and in waterways, where they enter the food chain. Dioxins are potentially lethal persistent organic pollutants that can cause cancer and disrupt thyroid and respiratory systems, according to the United Nations Environmental Programme (UNEP). 

Pollution hotspots – South Asia, Sub-Saharan Africa, South-East Asia

Just nine countries account for more than half of mismanaged plastics pollution emissions to the air, land and water, in absolute terms. But some countries with low absolute emissions rank high in per capita terms. For example, China, the world’s fourth largest emitter of plastics pollution has a very low per-capita emission rate, while South Sudan has high per-capita rates but low overall emissions. 

In Latin America and the Caribbean, hotspots for per-capita emissions include municipalities in Paraguay, Belize and Haiti.

The study anticipates that Sub-Saharan Africa will become the world’s largest source of plastic pollution within the next few decades as absolute and per-capita emissions continue to climb. Several megacities stand out as key hotspots, including Lagos, Nigeria; Juba, South Sudan; and Nouakchott, Mauritania.

“Across the continent, there is barely any plastic treatment infrastructure in place,” said a WHO Africa Region article on plastic waste.

Waste scavengers on the front lines of exposures

In lieu of government waste collection, “waste-pickers” in the informal sector generally collect and sort plastics – burning much of it to recuperate valuable metals, including wire and other materials that they can then sell or reuse. 

Globally, nearly 60% of all plastic waste globally is collected by waste scavengers in the informal sector. Over 20 million people around the world earn an income in the informal waste sector, collecting, sorting, and selling materials for recycling or reuse, according to the UN Environmental Programme (UNEP). Around 20% of waste scavengers are women, and an uncounted number are children, a 2021 WHO report estimates. The job is hazardous and exposures to the toxic soup of chemicals, directly and through airborne pathways, can cause respiratory illnesses and skin infections, as well as cancers. In addition, women and children are at risk from adverse reproductive and developmental health effects. 

Advocates for safer conditions urge governments and companies to accept Fair Circulatory Principles so that the human rights of waste pickers and other informal workers are recognized. 

The estimates highlight the huge disparities in how countries are able to grapple with plastic waste.  For much of the Global South, waste mismanagement drives pollution, while the Global North’s robust waste collection and management means that a much smaller fraction of plastic waste ends up in the local environment.

Raising awareness about plastics air pollution exposures – and hopes for consideration in a treaty

The updated estimates of pollution from plastics waste, and particularly from incineration, comes just a few months before the next round of negotiations at the Intergovernmental Negotiating Committee on Plastic Pollution in Busan, South Korea, 25 November-1 December.

The study authors hope negotiators will consider the burden of openly burned plastic, a topic that has “not formed a central part of discussions.”

Pathak stressed that “plastic pollution awareness campaigns or policies that focus only on plastic litter can often lead to increased open plastic burning, as communities and local officials engage in clean-up activities to care for their spaces or to meet waste management goals.

“Given low levels of awareness regarding the harms and the persistence of the toxicants from open burning and a lack of real alternatives to deal with collected wastes, communities often end up burning them. This is why it is crucial that policies and interventions to target plastic pollution, especially global interventions designed in the Global North, take a comprehensive view of the plastic problem and pay attention to local constraints and capacities.”

Korfmacher also echoed the need for research and awareness into “how plastics enter the human body and what effects different sizes, shapes, and types of plastics have on human health.” 

Image Credits: S. Samantaroy, Nature , SweepSmart, Nature/Cottom et al, 2024, WHO,2021.