A sweeping new study in the Journal of Environmental Management has amassed the largest-ever continuous dataset on plastic pollution in rivers globally, classifying 66% of the debris analyzed as macroplastic — or large, visible pieces of plastic like bottles, bags, straws and cutlery. Whereas much plastic pollution research relies on models and estimates to make their conclusions, this dataset draws on an unparalleled, locally-led global effort to count trash found in rivers.
“We know that rivers worldwide are clogged with plastic — and that this plastic often ends up in the ocean. Researchers have provided large-scale modeling to show how this plastic travels from land to rivers to the ocean. This is the first on-the-ground data that helps shed light on why plastic is showing up in rivers in the first place, ” said lead author of the study, “Assessing macroplastic debris collected from eight diverse river systems across four continents: Insights from synchronous three-year community-led research efforts,” Chase Brewster, a project scientist in UCSB’s Benioff Ocean Science Laboratory.
The research by experts at the University of California, Santa Barbara, used on-the-ground data from plastic-clogged rivers in Mexico, Jamaica, Panama, Ecuador, Kenya, Vietnam, Thailand and Indonesia. The study provides a valuable source of hard data on the scale of the plastic crisis amid negotiations this week at INC-5.2 in Geneva, Switzerland, to finalize an agreement to end plastic pollution.
“Negotiators and country officials can use this data to assess the river plastic pollution problem in real life, look at differences in pollution in different places, and test ideas about what policies and systems are working,” Brewster said.
Based on their study, researchers offer four key recommendations to help solve the plastic pollution problem:
- Implement policies such as minimum recycled content, bottle deposit fees, and virgin production caps to create market conditions for a circular economy
- Support the informal waste-picking sector while investing in waste management and recycling infrastructure and services
- Conduct more consistent and more transparent monitoring and data collection to inform targeted upstream actions
- Pursue thoughtful, well-designed local and national policies as well as ambitious international frameworks to address the different scales of the problem
To gather data, researchers worked with local partners to collect data from river sites between 2020 and 2023, with teams collectively removing and analyzing 3.8 million kilograms of river debris (equivalent to 380,000,000 single-use plastic water bottles). This large-scale, synchronous effort — rare in its scope and level of coordination — enabled researchers to compare data across diverse social, economic and environmental settings.
Researchers found substantial variation in the amount of plastic pollution intercepted in rivers studied, but all had plastic. Scaling up average plastic collection rates documented in this study would generate a preliminary estimate of 1.95 million metric tonnes (Mt) of plastic traveling down rivers worldwide every year. “That is an immense amount of plastic pollution,” said co-author and Director of the Benioff Ocean Science Laboratory, Professor Douglas McCauley.
Unique among many global pollution studies, the project took a community-led approach that emphasized local autonomy. Local nonprofits and social enterprises led the work in their own communities, sorting plastic waste by item type, polymer category, and other metrics. “Each site was an independent project,” Brewster explained. “They weren’t just collecting data. They were implementing technology to remove plastic from rivers, engaging governments, empowering communities, and improving local conditions.”
Together, these local teams form the Clean Currents Coalition, a global initiative directed by the Benioff Ocean Science Laboratory to intercept plastic before it reaches the ocean while fostering education and employment, restoring habitats, investing in local infrastructure, and cultivating systemic change. Since 2020, the Clean Currents Coalition has removed more than 7.3 million kilograms of debris (over 4.4 million kilograms of it plastic) from rivers worldwide.
“This work is really about turning off the tap of plastic pollution at its source,” Brewster added. “It’s not just cleaning rivers, it’s about doing purposeful science and supporting the communities that are the real leaders that will make this change last.”