Dog Waste Is a Hidden National Pollutant: New Model Tracks Where It All Goes

Every year, millions of pet dogs across South Korea produce a stream of urine, feces, plastic pads, and waste bags that vanishes into the environment with almost no accounting. A new study published in Environmental Monitoring and Assessment has, for the first time, built a national-scale model that follows this material pathway by pathway, revealing that pet dog waste is a surprisingly large and largely invisible contributor to both freshwater pollution and greenhouse gas emissions. The research, led by Jaeho Lee, Junbeum Kim, and Dowan Kim of Seoul National University of Science and Technology, offers the first comprehensive framework for quantifying how companion animal excreta moves through municipal solid waste systems, sewer networks, and the wider environment.

The team’s approach is a mass-balance model, a type of accounting tool widely used in industrial ecology to track materials through a system. Rather than treating pet waste as a single undifferentiated mass, the model resolves it into three disposal routes and four material categories. The disposal routes are volume-based waste, the fraction that ends up mixed into general municipal solid waste; the sewer system, which receives waste flushed or washed into drains; and the soil-water pathway, where waste deposited outdoors on walks or in yards is released directly to land and subsequently transported into freshwater bodies. The material categories distinguish urine, feces, disposable pads, and plastic waste bags, each of which carries a distinct environmental signature.

This resolution matters because the environmental consequences of each pathway differ dramatically. Urine deposited on soil during a walk carries dissolved nitrogen that can readily leach into streams and rivers. Feces left uncollected contributes both nutrients and pathogens. Plastic pads and bags, by contrast, contribute little to nutrient loading but add substantially to municipal plastic waste and, through their manufacture and disposal, to carbon emissions. By separating these flows, the model can identify which interventions would actually reduce which pollutants, something aggregate estimates of pet waste have never been able to do.

To populate the model, the researchers drew on an unusually diverse set of data sources. National surveys of companion animal ownership provided the dog population and owner behavior patterns, including walking frequency and pad usage. Veterinary and animal nutrition literature supplied the nitrogen and phosphorus concentrations in canine excreta, as well as fecal dry-matter content, which varies with diet and body size. Product specifications from commercial listings informed the plastic composition and mass of disposable pads and waste bags. Official government statistics on municipal solid waste generation, sewer coverage, and approved greenhouse gas emission factors anchored the model to South Korea’s actual waste and wastewater infrastructure. Soil-to-water delivery ratios, adapted from methodologies used in total pollutant load management systems, determined how much of the waste released on land ultimately reaches freshwater.

The headline finding is a stark picture of where the waste actually goes. Nationally, 57.5 percent of pet dog waste enters the volume-based waste stream, ending up in the municipal solid waste system, often sealed inside plastic bags. Another 30.2 percent follows the soil-water pathway, released outdoors and never collected. The remaining 12.3 percent enters the sewer system. In other words, nearly a third of everything the country’s pet dogs excrete bypasses formal waste management entirely and becomes a diffuse source of environmental pollution.

The consequences for freshwater quality are dominated by that outdoor fraction. The model estimates that diffuse releases deliver approximately 2.20 kilotonnes of nitrogen and 157 tonnes of phosphorus to South Korean freshwaters every year, with urine runoff and uncollected feces as the primary carriers. These nutrients are the classic drivers of eutrophication, the process by which excess nitrogen and phosphorus fertilize algal blooms that deplete oxygen, kill fish, and degrade drinking water sources. While agriculture and wastewater treatment plant overflows are the usual suspects in nutrient management planning, this study shows that pet dogs constitute a meaningful and entirely unmanaged contributor to the same problem, one that has never appeared in national nutrient budgets.

The climate story is different but no less significant. Pet dog waste generates an estimated 45.9 kilotonnes of carbon dioxide equivalent per year in South Korea, and the dominant source is not the excreta itself but the disposable pads. These absorbent plastic-backed products, used heavily in apartments and by owners of indoor dogs, embody plastic production emissions and generate waste that must be incinerated or landfilled. The finding echoes earlier international research identifying dog poop bags as a non-negligible source of plastic pollution, but extends it to a product category whose environmental cost has been almost entirely overlooked in national inventories.

One of the study’s most interesting insights concerns behavioral trade-offs. The sensitivity analysis reveals that outdoor walking frequency and disposable pad usage act as opposing drivers that shift waste between the solid waste and sewer systems. An owner who walks the dog frequently and relies on pads sparingly routes more waste outdoors, increasing diffuse nutrient losses to water. An owner who keeps the dog indoors with heavy pad use generates more plastic waste and carbon emissions but fewer nutrient releases to the environment. Neither behavior is environmentally benign; the burdens simply migrate between pathways. This means that policies targeting a single pathway, such as pad disposal programs or park cleanup campaigns, risk displacing pollution rather than reducing it unless they account for these trade-offs.

The sensitivity tests also highlight which parameters most influence the results: pad usage rates, fecal dry-matter content, and hydrologic delivery ratios. This matters for reproducibility and for adapting the framework to other countries, where dog ownership densities, walking cultures, and waste infrastructure differ. South Korea is an instructive case because its high-rise urban living, widespread pad use, and dense dog population combine to create a distinctive waste profile, but the model’s structure is generic. Any nation with data on pet populations, owner behavior, and waste treatment could apply the same pathway-resolved accounting, filling a gap that existing nutrient and solid waste models have left open worldwide.

What emerges from the study is both a warning and an opportunity. The warning is that pet dog waste, amplified by booming companion animal ownership in densely populated countries, has grown into an environmental load comparable to recognized pollution sources yet remains absent from nutrient management plans, plastic reduction strategies, and greenhouse gas inventories. The opportunity lies in the model’s demonstration that behavioral interventions targeting pet owners, such as promoting prompt feces collection, moderating pad consumption, and improving disposal infrastructure in parks and apartment complexes, offer effective and low-cost routes to urban household waste minimization. Because the burdens are pathway-specific, mitigation can be targeted: reducing uncollected outdoor waste attacks eutrophication directly, while cutting pad and bag consumption addresses plastics and emissions. The researchers present their framework as a reproducible tool for integrating pet dog waste into national nutrient management and solid waste planning, and it is easy to imagine municipalities using it to prioritize where collection stations, composting pilots, or public education campaigns would deliver the greatest environmental return. As pet ownership continues to rise globally, the humble dog walk, it turns out, is a matter of national material accounting.

Subject of Research: National-scale quantification of environmental nutrient and carbon loads from pet dog waste across disposal pathways in South Korea

Article Title: A pathway-resolved national model for quantifying environmental loads from pet dog waste: a case study of South Korea

Article References: Lee, J., Kim, J., & Kim, D. (2026). A pathway-resolved national model for quantifying environmental loads from pet dog waste: a case study of South Korea. Environmental Monitoring and Assessment, 198(10), Article 1060. https://doi.org/10.1007/s10661-026-15869-y

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15869-y

Keywords: pet dog waste, mass-balance model, eutrophication, nitrogen, phosphorus, municipal solid waste, plastic pollution, greenhouse gas emissions, wastewater, South Korea, companion animals, nutrient management