A 2021 study published in Science Advances estimated that the Philippines contributes 356,371 metric tons of plastic to the ocean each year, equivalent to 36% of global riverine plastic emissions from 4,820 rivers.
The estimate has since been widely cited in claims that the Philippines is the world’s No. 1 source of ocean plastic pollution. But the figure was generated by a model, not by direct nationwide measurements of plastic entering the sea.
The model used a 2015 baseline and national averages, including waste generation of 0.5 kilogram per person per day and an 81% waste-mismanagement rate. It did not stratify waste generation by income or locality, directly sample household waste segregation, or account for cleanup and waste-management initiatives carried out in later years.
This report examines the assumptions behind that estimate and argues that any updated assessment should incorporate more recent barangay waste audits, direct river-flux measurements and Extended Producer Responsibility compliance data.
It also draws on field observations from Virac, Catanduanes; Bay, Laguna; and the Pasig River, where cleanup efforts and changes in waste management have altered conditions since the baseline data used in the model were collected.
The analysis also considers corporate accountability. Break Free From Plastic brand audits cited in the report have identified Coca-Cola, Nestlé and Unilever among major sources of branded plastic waste in the Philippines, while World Bank reports have emphasized circular-economy infrastructure, policy reforms and improved waste-management systems.
How a modeling paper became a national label
The estimate that the Philippines contributes 36% of global riverine plastic emissions came from a 2021 Science Advances study by Meijer and co-authors on plastic emissions from more than 1,000 rivers.
The study, associated with The Ocean Cleanup, was intended to help prioritize river interventions globally. Its modeling framework, however, was often reduced in subsequent coverage to a ranking of countries by their contribution to ocean plastic pollution.
The Philippines, with 7,641 islands, 421 principal rivers and high rainfall, ranked at the top of the model. The result did not mean Filipinos were necessarily the world’s most wasteful consumers. The model assigns higher probabilities of plastic reaching the ocean to short, steep and densely populated tropical catchments.
Geography, therefore, plays a major role in the result.
The author, a farmer and practitioner in Bay, Laguna, who has also observed conditions in Virac, Catanduanes, questions whether a single national waste-generation average can accurately represent a country with wide income disparities and an active informal recycling sector.
The equation that created the ranking
Meijer and co-authors described their modeling framework in the Science Advances study.
Plastic emissions at a river mouth, or ME, were calculated as the accumulation of mismanaged plastic waste, or MPW, multiplied by the probability that the waste would reach the ocean, or P(E), within a river basin:
ME = S [MPW_ij × P(E)_ij]
MPW_ij represents the mass of mismanaged plastic waste produced in a grid cell, while P(E)_ij represents the probability that the waste will be emitted into the ocean.
The probability of emission was further divided into three components:
P(E) = P(M) × P(R) × P(O)
P(M) is the probability that plastic waste will be mobilized, based on factors such as wind and precipitation.
P(R) is the probability that mobilized waste will reach a river, based on factors including distance from a river, slope and land use.
P(O) is the probability that waste already in a river will reach the ocean, based on distance from the river mouth and river discharge.
One key input, MPW, was calculated as:
MPW = Population × Waste generation per capita × Fraction plastic × Fraction mismanaged
For the Philippines, the model used a 2015 baseline. Population figures came from WorldPop, while the waste-generation figure of 0.5 kilogram per person per day came from the World Bank’s 2018 ‘What a Waste 2.0’ report. The model also used a plastic fraction of 12% to 15% from national waste-composition studies and an 81% mismanaged-waste rate from a 2015 Science study by Jambeck and co-authors.
Under those assumptions, each Filipino was modeled as generating 182.5 kilograms of waste a year, including 23.7 kilograms of plastic, of which 19.2 kilograms was considered mismanaged.
With P(E) estimated at about 17% for Philippine catchments because of factors such as short distances to the sea and heavy rainfall, the model produced an estimate of 3.26 kilograms of plastic per person per year entering the ocean, or 356,371 metric tons nationwide.
The report contrasts this with India, where the model used waste generation of 0.43 kilogram per person per day and an 87% mismanagement rate. Because much of the Ganges basin is more than 1,000 kilometers from the ocean, the model assigned a P(O) of less than 1%, resulting in an estimated 0.09 kilogram per person reaching the ocean.
The comparison shows how sensitive the model is to geography in addition to assumptions about waste generation and management.
Meijer and co-authors also acknowledged substantial uncertainty in the model. Their predictions could vary by a factor of four within a 68% confidence interval and by a factor of 10 within a 95% confidence interval.
Applied to the Philippine estimate, that uncertainty would produce a wide possible range around the central estimate of 356,371 metric tons.
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The 0.5-kilogram per capita figure is based on older averages
The waste-generation figure of 0.5 kilogram per person per day came from the World Bank’s 2018 ‘What a Waste 2.0′ report, which relied on data from 2012 to 2016.
The report argues that applying a single figure nationwide does not reflect differences in waste generation among communities and income groups in the Philippines.
Waste Analysis and Characterization Studies by the National Solid Waste Management Commission and DENR cited in the report show such differences. Metro Manila generates about 0.69 kilogram of waste per person per day, compared with 0.51 kilogram in highly urbanized cities and 0.30 kilogram in rural municipalities. The figure for some rural barangays is cited at 0.15 to 0.20 kilogram.
Those differences matter because applying a uniform national average can assign the same waste-generation rate to households with very different consumption patterns and waste-management practices.
The data used to estimate mismanaged waste have also changed since the model’s baseline year.
Under the Ecological Solid Waste Management Act of 2000, or Republic Act No. 9003, waste collection and disposal systems have expanded. According to DENR figures cited in the report, collection coverage increased from 40% in 2010 to 70% in 2022.
The report also notes that subdivisions and organized barangays in Laguna, Cavite and Virac have adopted segregated collection systems in which biodegradable waste is composted, recyclables are sent to junk shops and residual waste is taken to disposal facilities.
The model classifies waste as mismanaged when its final disposal site is an open dumpsite.
DENR reported 353 open dumpsites operating in 2019. By 2023, the agency had reported the closure of 335 open dumpsites as disposal systems shifted toward controlled facilities and sanitary landfills.
The report argues that the 81% mismanaged-waste assumption reflected conditions closer to the model’s 2015 baseline than to conditions from 2023 onward.
The model also does not separately account for the informal waste sector. The Philippines has an estimated 500,000 informal waste pickers, including magbobote and mangangalakal, who recover recyclable material before it reaches disposal sites.
The report estimates that informal recovery accounts for 20% to 30% of recyclable plastics. Because such activity may not appear in official collection data, the report argues that it can reduce the amount of plastic available to enter rivers without being fully reflected in the model.
The Meijer model identified the Pasig River as the world’s single highest-emitting river, with an estimated 63,000 metric tons of plastic a year, or 17.6% of the Philippine total.
The report says the estimate reflected conditions around 2017 and 2018, when the Pasig River was heavily polluted.
Conditions have changed since then.
The Pasig River Rehabilitation program under the PRRC and DENR, with private-sector participation, reported removing 1.2 million metric tons of waste from Pasig tributaries from 2019 to 2024.
Trash traps have also been deployed in the San Juan River, while The Ocean Cleanup’s Interceptor 001 and 002 have operated in the Tullahan River since 2021. Metropolitan Manila Development Authority River Rangers also conduct regular cleanup operations.
The report argues that these interventions have substantially reduced visible floating macrolitter. Based on the author’s observations, the floating masses of plastic associated with the Pasig River in 2018 were no longer a daily sight by 2025, although the river had not returned to the condition remembered from the 1950s, when people swam in it.
The report notes that the national model has not been recalibrated using post-2021 data from these interventions.
Similar differences can be seen in smaller waterways.
In Virac, Catanduanes, the author observed that the river passing through the poblacion was generally clear of floating plastic. The municipality has an ordinance restricting single-use plastics, along with community cleanup activities and relatively low industrial activity.
In Bay, Laguna, rivers flowing toward Laguna de Bay, including the Calo and Sapang rivers, are not pristine. But after heavy rains, the author observed that the more visible load was often eroded brown soil rather than floating plastic.
The author also observed bottle-return practices at sari-sari stores and barangay material recovery facilities that, while imperfect, capture some plastic before it reaches waterways.
Soil erosion remains another environmental concern.
The Food and Agriculture Organization’s Global Forest Resources Assessment for the Philippines cited a deforestation rate of 157,000 hectares a year from 1990 to 2010. After heavy rains, soil from degraded watersheds can enter waterways and turn rivers brown.
In the author’s observations in Laguna, sediment was often more visually prominent than plastic bottles and was a concern for aquatic ecosystems and fisheries in Laguna de Bay.
What a fair methodology should be
A more current assessment of Philippine plastic pollution would rely more heavily on direct measurement and locally differentiated data rather than a single national average.
The report proposes:
income-stratified waste-generation audits at the barangay level, consistent with the Waste Analysis and Characterization Studies required under Republic Act No. 9003, rather than a uniform 0.5-kilogram-per-person daily estimate;
recognition of plastic recovered by the informal waste sector before it reaches disposal sites or waterways;
direct and seasonal measurements of river plastic flows using collection methods such as nets, rather than relying solely on probabilities derived from rainfall and geography;
consideration of watershed deforestation and soil erosion alongside plastic pollution, particularly in rural rivers; and
regular recalibration of models after major cleanup and waste-management interventions.
The report does not dispute that plastic pollution remains a serious problem in the Philippines, particularly because of the widespread use of sachets.
World Bank figures cited in the report put sachet consumption in the country at 163 million pieces a day, many of which have low recyclability.
The report argues, however, that applying a single waste-generation figure nationwide can obscure significant differences among households and communities. A household that composts organic waste or sells recyclables to informal collectors does not necessarily have the same leakage profile as waste sent to an unmanaged dumpsite.
Direct river-flux studies and field sampling, the report argues, would provide a clearer picture of how much plastic actually reaches waterways and how those flows change across seasons.
The report also points to corporate responsibility.
The Plastic Tort Administrative Complaint cited in the report argues that the production of nonrecyclable sachets and packaging by multinational companies, including Coca-Cola, Nestlé and Unilever, exceeds the capacity of local material recovery systems.
Break Free From Plastic brand audits similarly place greater attention on the producers and brands associated with discarded packaging, rather than assigning responsibility solely on the basis of where waste is found.
Conclusion
The widely cited estimate that the Philippines contributes 36% of global riverine plastic emissions is not a direct measurement of individual behavior or of all plastic physically entering the ocean.
It is the result of a model based on mismanaged plastic waste and probabilities of mobilization, river transport and ocean transport:
MPW × P(M) × P(R) × P(O).
The report argues that the estimate remains useful as a call to address plastic pollution but should be understood within the limitations of the model and the age of its underlying data.
The 0.5-kilogram-per-person daily waste input is an average rather than a measurement of every Philippine household. It does not account for differences in income, locality, recovery practices or waste-management systems.
A more current assessment would incorporate barangay-level waste audits, informal recovery rates and direct river-flux measurements. It would also take into account changes brought by cleanup programs, expanded waste-management infrastructure and the implementation of the Extended Producer Responsibility Act of 2022.
Field observations in Virac and Bay cited in this report suggest that some waterways now contain less visible floating plastic than they did in previous years, even as soil erosion and sediment remain serious concerns.
The author argues that these conditions also connect environmental security with food security: protecting watersheds can reduce soil loss while improved waste management can reduce plastic leakage.
Any updated national assessment would also need to account for changes since the original model’s baseline, including river cleanups, EPR implementation and the expansion of material recovery and sanitary disposal facilities.
The report concludes that empirical sampling and locally stratified waste audits would provide a stronger basis for assessing the Philippines’ contribution to ocean plastic pollution. It also argues that such assessments should consider corporate production and packaging practices, government waste-management systems, informal recovery and community cleanup efforts alongside national estimates of mismanaged waste.