Once produced, plastics are formed into a range of products that are used for a period of time. Some products, such as packaging, may have a very short use time while other more durable plastic products may remain in use for decades. There can be a short or long lag time between plastic production and its transformation into plastic waste. Plastic waste is created when, intentionally or unintentionally, plastics are taken out of use and enter a waste stream as part of a waste management process or are released into the environment.
This chapter first presents global estimates of plastic waste, followed by a detailed look into U.S. municipal solid waste (MSW) characterization, generation, and management. Other sources of U.S. plastic waste are explored. “Leaks” of plastic waste into the environment are discussed. Lastly, this chapter reviews the current regulatory framework of plastic waste management in the United States. Subsequent chapters identify transport, pathways, distribution, and fate of plastic waste that leak to the environment and ultimately to the ocean.
Plastic waste generation is directly related to the quantity of plastics produced and used. Understanding and estimating plastic waste generation can be challenging; there are a few different estimates from the past few years, which are summarized in Table 3.1. In terms of cumulative generation of plastic waste, Geyer, Jambeck, and Law (2017) estimate
that from 1950 through 2015, 6.3 billion metric tons (BMT) of plastic waste were generated globally (Figure 3.1). In addition, Geyer, Jambeck, and Law (2017) estimated that in 2015, 302 million metric tons (MMT) of global plastic waste were generated. According to World Bank annual estimates, in 2016, the world generated 2.01 BMT of waste, of which 242 MMT was estimated to be plastic waste (Kaza et al. 2018). With cumulative quantities of plastic production projected to reach 34 BMT and plastic waste projected to reach 26 BMT by 2050, the total amount of plastics in the waste stream is projected to grow (Geyer, Jambeck, and Law 2017) (Figure 3.1).
Table 3.1 also indicates national estimates for U.S. plastic waste generation with estimates of 42 MMT in 2016 by Law et al. (2020) and 32 MMT in 2018 by the U.S. Environmental Protection Agency (U.S. EPA 2021c).
Municipal Solid Waste
This chapter describes solid waste management and primarily focuses on MSW, what people throw away every day at home and on the go. It is typically measured in mass per person (per capita) generation rates. This chapter does not include intentional/permitted or unintentional land-based air, water (whether wastewater, stormwater, or other water), or
TABLE 3.1 Recent Estimates of Annual and Cumulative Generation of Plastic Waste in the United States and Globally
|Data Source||Annual Plastic Waste Generation||Cumulative Waste Generation Since ∼1950|
|U.S. EPA 2021c||32 MMT in 2018||–||[1,000] MMT||–|
|Law et al. 2020||42 MMT in 2016||–||–||–|
|Geyer, Jambeck, and Law 2017||–||302 MMT in 2015||–||6,300 MMT in 2015|
|Kaza et al. 2018||242 MMT in 2016|
NOTE: Square brackets indicate “on the order of” or “approximately.” These estimates were completed by the committee using available data.
sludge (e.g., from wastewater treatment plants) discharges that may also contain plastics (usually smaller particles such as pre-production plastics or microplastics from clothing) unless they are disposed of as solid waste. It also does not apply to marine discharges (e.g., lost during shipping, lost or discarded fishing gear) unless recovered and deposited in a solid waste management system. Information on non-solid waste discharges and leakage is included in subsequent chapters.
Municipal Solid Waste Generation
The U.S. per person MSW generation rate ranges from 2.22–2.72 kg/day (4.9–6 lb/day) (EREF 2016, Powell and Chertow 2019, U.S. EPA 2021e). This is 2–8 times the waste generation rates of many other countries (Law et al. 2020). Figure 3.2 can be examined to see other countries’ waste generation per capita. The United States generated about 321 MMT of waste in 2016, amounting to 16% of the world’s waste (Kaza et al. 2018, Law et al. 2020). In 2016, the United States was the top generator of plastic waste (Law et al. 2020). This is despite containing 4.3% of the world’s population (World Bank 2021) and being the third most populous country in the world.
In theory, managed solid waste in the United States should not contribute to ocean plastic waste because it is contained by treatment and/or conversion into other products (recycling, composting, incineration) or contained in an engineered landfill environment. In practice, plastic waste still “leaks” from managed waste systems when blowing out of trash cans,
trucks, and other managed scenarios. Waste not put into the management system, whether intentionally or unintentionally through actions such as illegal dumping and littering, is considered unregulated and illegal waste in the United States.
Data on MSW are compiled by U.S. EPA through a materials flow analysis method. The quantities are estimations based on production, along with lifetimes for various products and sectors to estimate the quantity of waste generated in each sector and for particular products. Data are also measured by other industry and academic groups, states, and even cities to inform local waste management. The management of MSW typically takes place at the city or county level in the United States, and nearly every household is provided with a method to formally manage their waste. Other waste streams in the United States that may contain plastics also are described in this chapter, although little is known about their contribution to ocean plastic waste.
Municipal Solid Waste Characterization
U.S. EPA’s Sustainable Materials Facts and Figures report, which calculates estimates as far back as 1960 and has been published periodically for more than 20 years, focuses on MSW. According to U.S. EPA, the MSW items include “packaging, food, grass clippings, sofas, computers, tires and refrigerators.” However, U.S. EPA does not include in its analysis any materials disposed of in non-hazardous landfills that are not generally considered MSW such as construction and demolition debris, municipal
wastewater treatment sludges, and non-hazardous industrial waste, some of which may be composed of plastics.
According to U.S. EPA, the generation of waste is the
weight of materials and products as they enter the waste management system from residential, commercial, and institutional sources and before recycling, composting, combustion or landfilling take place. Pre-consumer (industrial) scrap is not included in the waste generation estimate. Source reduction activities, such as backyard composting of yard trimmings, take place ahead of generation.
U.S. EPA’s materials flow methodology does not consider any “mismanagement” of waste within the United States, such as illegal dumping or littering.
The U.S. EPA MSW characterization describes waste both by material type—paper, plastics, metal, glass, etc.—and by-products, which are separated into durable goods (typically stay in use more than 3 years), nondurable goods (stay in use less than 3 years), and containers and packaging (typically enter the waste stream the same year they are purchased). Examples of durable goods include appliances, furniture, casings of lead-acid batteries, and other products. Examples of nondurable goods include disposable diapers, trash bags, cups, utensils, medical devices, and household items such as shower curtains. U.S. EPA does not include plastics in transportation products, other than lead-acid batteries, in its management analysis (U.S. EPA 2021e).
U.S. EPA estimated that 12.2% of MSW (by mass) was plastics (32.4 MMT) in 2018. However, the estimate for annual generation of plastic solid waste has been as high as 42 MMT when using waste generation rates derived from waste disposal data from MSW management facilities (Law et al. 2020). Plastics are the third-highest percentage of material (by mass) in MSW after paper and food waste, and are slightly higher than yard waste (Figure 3.3).
The steep increase in plastic production described in the previous chapter has been mirrored by an increase in the percent of plastics in U.S. MSW (by mass)—from 0.4% in 1960 to 12.2% in 2018, with a peak of 13.2% in 2017 (U.S. EPA 2020a). The mass of plastic waste generated has been increasing in the United States since 1960, with the fastest increase occurring from 1980 to 2000 (Figure 3.4).
Municipal Solid Waste Collection
Residential waste is a category of MSW. MSW is broader and includes waste from single-family homes to multi-family housing and waste from commercial and institutional locations, such as businesses, schools, and hospitals. Generally, single-use plastics used in the home and packaging for
any packed food items will end up in the residential waste stream, as will longer-lived durable goods, when disposed of. In the United States, the residential waste and recycle stream usually is picked up at people’s homes by the local community (paid through either fees or taxes) or a private hauler (hired by the resident), or the resident takes the waste to a transfer station or
directly to a management facility (e.g., landfill or recycling facilities called material recovery facilities [MRFs]). Plastic waste generation at the residential level is not measured or monitored directly. Community members typically do not know how much or what kind of waste they generate. Residential waste and mass of items collected for recycling are recorded at the community level through landfill or MRF disposal. Garbage truck weight is measured at the landfill scale houses to calculate tipping fees (e.g., a fee to pay for waste disposal). Outgoing trucks of baled materials (e.g., bales of plastics, such as polyethylene terephthalate [PET] or mixed plastics) that are shipped to processing facilities for recycling are also weighed.
Since solid waste is typically measured in mass (e.g., for solid waste audits, “tipping” fees at disposal facilities), but plastic bulk density is low, it weighs very little for how much space it takes up if uncompacted. The bulk density (the weight of the waste divided by the volume it occupies, including the space between waste items) of uncompacted mixed plastics is approximately 121 lb/yd3 (72 kg/m3). For example, trash may look like it is composed mostly of plastics because film plastics spread out and look large owing to their surface area, and empty plastic containers still take up the space that held the product.
Waste collection methods are often determined by population density. For low population densities, curbside collection may not be economically feasible and residents may be required to take their own waste to a transfer station for drop-off, which puts an extra burden on residents. Rural areas not served by curbside collection may manage more MSW, including plastics, “at home” through open burning and dumping privately/illegally (Tunnell 2008). In Virginia, for example, open burning is still allowed if there is no regular trash collection.1 With population density as a driver for waste generation, higher density areas such as urban and suburban areas generate more plastic waste per unit area than rural areas; however, urban areas have more developed waste management infrastructure (e.g., more curbside collection and recycling) than rural areas. This pattern occurs globally as well as in the United States (Schuyler et al. 2021, Youngblood et al. In Review).
Although plastic waste quantities generated in urban and rural areas differ and the proportion of plastic waste not collected or captured by waste management systems varies, both are sources of ocean plastic waste (see subsequent chapters). Regardless of population density or land use, coastal areas have greater connectivity to the ocean, placing any
1 Code of Virginia § 10.1-1308; Clean Air Act; §§ 110, 111, 123, 129, 171, 172, and 182; 40 CFR Parts 51 and 60. “Open burning is permitted for the on-site destruction of household waste by homeowners or tenants, provided that no regularly scheduled collection service for such refuse is available at the adjacent street or public road.”
uncollected plastic waste from urban, suburban, rural, recreational, industrial, or other human activities at a higher risk of ending up in the ocean. Coastal areas might be subject to greater efforts to reduce, collect, and divert plastic waste sources, but inland areas, especially along waterways, should be managed to reduce plastic wastes moving toward the ocean.
Municipal Solid Waste Management
In 2018, to manage MSW, the United States landfilled 50%, recycled 24%, composted 8.5%, and combusted 12% of all MSW (U.S. EPA 2021e). Of plastics in MSW, 75.6% were landfilled (comprising 18.5% of all landfilled materials, by mass), 8.7% were recycled, and 15.8% were combusted with energy recovery. While both recycling and combustion capacity expanded in the 1980s and 1990s, these percentages have remained relatively consistent over the past 15 years (Figure 3.5).
Decisions about how waste, including plastic waste, is managed are made by state and local governments and other groups, who bear the growing costs and challenges of managing increasing amounts of waste. Plastic products disposed as waste (reported by U.S. EPA in durable goods, nondurable goods, and containers and packaging categories) consist of a wide variety of plastic polymers containing mixtures of chemical
additives that allow for an array of properties (Deanin 1975). Thus, the composition of plastics in MSW is incredibly diverse, which creates challenges in waste management systems, especially when sorting materials for appropriate recycling or composting.
Since the Resource Conservation and Recovery Act (RCRA) passed in 1976, landfills are lined with composite liners to protect the soil and groundwater (e.g., geomembrane and 2 feet of compacted clay), and the liquid that permeates and seeps through the landfill waste is collected and removed. Landfills are sloped to one side with a drainage layer (e.g., sand) so the liquid can quickly run off the liner, collect, and then be pumped out of the landfill. Trucks deposit waste onto the working face of the landfill and bulldozers move the waste. Compactors compress the waste so the landfill is as dense as possible. Once the landfill has reached its fill height, gas wells are installed throughout the landfill to collect released gases (i.e., methane, carbon dioxide, nitrogen, and other trace gases). The landfill is then capped with an impermeable layer, which is similar to the bottom layer. Sometimes soil and grass are placed on top of the landfill. After the landfill is closed, it requires at least 30 years of monitoring.
None of the highest-production plastics (PET, high-density polyethylene [HDPE], polyvinyl chloride [PVC], low-density polyethylene, polyethylene [PE], polystyrene [PS]) biodegrade in a landfill, and they are considered contamination in compost. Since plastic products also contain an array of additives (Deanin 1975), this diversity of plastic waste can challenge recovery and recycling. In addition, plastics can be mixed with food waste, most of which goes to landfills (only 6.3% of food waste is composted, as compared with 69.4% of yard waste, which is restricted from landfills).
With the vast majority (76%) of managed plastic waste disposed of in landfills, there are opportunities to reduce this amount and conserve non-renewable resources, increase energy efficiency, and provide economic and environmental benefits through effective source reduction, recycling, and composting. These options are in line with U.S. policy to prevent and reduce pollution at the source whenever feasible (Pollution Prevention Act). These principles are expressed in the RCRA, where the order of preference in managing materials is source reduction, reuse, recycling, and disposal.
The statistics reported by U.S. EPA on plastic recycling reflect the amount of plastic waste collected for reprocessing into a secondary raw material, primarily by mechanical recycling. Mechanical recycling requires waste items
to first be sorted according to primary material type (polymer resin type), indicated on many household products by the numbered resin identification code (“chasing arrows” symbol). Products might be further sorted according to color, size, or density before being washed of residues or contaminants, then shredded or chopped into smaller particles that can be remelted and formed into a reprocessed material (Ragaert, Delva, and Van Geem 2017).
The increasing diversity and complexity of material and product types present major challenges to recycling, especially when waste is collected in “single-stream” recycling programs, which require mechanical and manual separation at MRFs. Contamination of individual plastic items by food or product residues, and of entire loads by items that are not recyclable (often by people “wish-cycling,” who place items in recycling collection in hopes they might be recycled), increases the difficulty and cost of separation (Damgacioglu et al. 2020). Furthermore, because plastics degrade throughout their life cycle and during reprocessing, recycled materials are frequently used in “downcycling” applications that do not require the same material quality standards as food-grade applications, for example (Ragaert, Delva, and Van Geem 2017). For these reasons and others, such as the low cost of primary (usually fossil) feedstocks used to make virgin plastics and fluctuating market demand for recycled materials, the economics of recycling can be extremely challenging (Rogoff and Ross 2016). Further details on where plastic scrap can be exported are illustrated in Box 3.1.
A suite of chemical processes, many of which are under development, that aim to break plastic waste down into chemical constituents, which may include the monomer building blocks of the original plastic (total depolymerization) or other intermediates (partial depolymerization), are broadly referred to as “chemical recycling” or “advanced recycling”. A major goal of chemical recycling is to produce secondary materials of the same or higher quality than the initial plastic waste itself (“upcycling”), ideally striving for many cycles of polymerization and depolymerization to maximize resource use (Coates and Getzler 2020). Presently, the only forms of chemical recycling utilized in the United States (and only at small scale) are energy-intensive pyrolysis and gasification processes, whose primary products are fuel and other chemical products rather than secondary polymers (Ragaert, Delva, and Van Geem 2017). Priority research opportunities have been identified to inform federal investment in research into new materials, together with the chemical processes to upcycle these materials once they become waste, to move toward a more circular life cycle for plastics (Britt et al. 2019).
Challenges include incompatibility of different plastic types and large differences in processing requirements (Closed Loop Partners 2020, Hopewell, Dvorak, and Kosior 2009, OECD 2018). Addressing these barriers to plastic recycling can produce co-benefits, including improving energy
efficiency, environmental performance, and process efficiency, while creating economic opportunities for new products (U.S. Department of Energy 2021). A variety of prizes or challenge competitions have been designed to stimulate innovation in overcoming the barriers associated with plastic recycling or to minimize reliance upon these difficult-to-manage materials (e.g., Department of Energy Plastics Innovation Challenge, New Plastics Economy Innovation Prize, the REMADE Institute, or the Bio-Optimized Technologies to keep Thermoplastics out of Landfills and the Environment [BOTTLE] Consortium), and some of these efforts have already produced results (Rorrer, Beckham, and Roman-Leshkov 2021, Shi et al. 2021).
High-production plastics such as PE, polypropylene, PS, and PVC are strongly resistant to biodegradation in any environment,
due to the strength of the carbon-carbon bond that constitutes the polymer backbone. Therefore, managed composting is not a suitable management strategy for the vast majority of today’s plastic waste, which would be contaminants in composting environments. A variety of certified compostable plastics (with ester backbones) have been developed to completely biodegrade (defined by complete metabolism by microorganisms in a specified time period) in managed composting facilities that maintain the specific environmental conditions required for material breakdown. However, the benefits of these products are lost if they are not collected and transported to managed composting facilities. In most regions of the United States, such facilities are not available. Even if there are nearby facilities, the consumer must recognize the item as compostable and place it in the correct collection bin, rather than in regular trash or in recycling collection, where it would contaminate the recycling stream (Law and Narayan 2022). Thus, the benefits of compostable plastics can only be realized if sizeable investments in composting infrastructure and consumer education occur.
Management of Plastic Containers and Packaging
Plastic containers and packaging comprise the largest fraction of the plastic waste stream (41%) and enter the waste stream most quickly after production in the year they are produced. Products in this category also commonly leak from the waste management system (see subsequent section on leakage). U.S. EPA defines plastic packaging as bags, sacks, and wraps; other packaging; PET bottles and jars; HDPE natural bottles; and other containers. It does not include single-service plates, cups, and trash bags, all of which are classified as nondurable goods. Plastic containers and packaging were the highest category within plastic materials in 2018 with an estimated 13.2 MMT generated, or approximately 5.0% of total MSW generation (U.S. EPA 2021c). In 2018, 1.8 MMT (13.6%) of plastic containers and packaging materials were recycled. However, this was lower than the quantity combusted with energy recovery, 16.9% (2.2 MMT), while the remainder (more than 69%) was landfilled (Figure 3.6). The two items most commonly recycled were PET bottles and jars at 29.1% (of total PET bottle waste generation) and HDPE natural bottles (e.g., milk and water bottles) at 29.3% (of total HDPE natural bottle generation). The higher rates of recycling are reflective of the product mass, with containers heavier than film plastics, and their more uniform design characteristics (monochromatic and with fewer additives), which makes these products easier to recycle and the recycled material more valuable.
Management by Designing for End of Life
The approach of designing products for end of life is embedded in the U.S. EPA’s Sustainable Materials Strategy and related programs (U.S. EPA 2015). However, there are many barriers, including a substantial mismatch between the materials that are created and the ability of the waste management system to accept and transform these materials into a second use or beneficial product (U.S. GAO 2020), such as being effectively recyclable or biodegradable.
Part of the solution to this mismatch is to adopt an integrated, life-cycle perspective (Walls and Palmer 2001) in the design of plastic products, especially single-use products, that explicitly accounts for direct and indirect costs associated with the product’s end-of-life disposal. This perspective would reduce the social cost of plastic disposal and waste leakage by pushing producers to design and use more easily biodegradable and recyclable/reusable materials, and by enabling consumers to choose products that permit low-impact disposal (Abbott and Sumaila 2019). Green Engineering principles (American Chemical Society 2021), if followed during material development and product design, can reduce the externalities associated with plastics. Circular economy concepts,
designed to promote “a regenerative system in which resource input and waste, emission, and energy leakage are minimized by slowing, closing, and narrowing material and energy loops thanks to long-lasting design, maintenance, repair, reuse, remanufacturing, refurbishing, and recycling” (Geissdoerfer et al. 2017), may be helpful as well.
Developing alternative materials or other product delivery systems can spark innovation and economic growth in the United States. There are several voluntary corporate commitments to change materials, use more recycled materials, and increase material circularity, so materials and infrastructure development to meet those demands are needed.2 Efforts could include sustainable packaging associations (precompetitive collaborations) to develop alternative materials and agree on more homogenized packaging designs for end of life, packaging with more value (e.g., single, homogenous materials; design for recycling/end of life), and designing out problematic items/materials (e.g., certain colors, smaller caps/lids). For composting to be a part of an integrated management approach, there is a need for both biodegradable materials and further development and expansion of composting infrastructure in the United States. For a more detailed approach to materials design, please see the recent article by Law and Narayan (2022).
Municipal Solid Waste Management Disparities and Environmental Justice
U.S. EPA defines environmental justice as “the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation and enforcement of environmental laws, regulations and policies.” (U.S. EPA 2021b). Environmental justice is one of the top priorities of the current U.S. EPA Administrator, Michael S. Regan (U.S. EPA 2021b). Impacts to vulnerable populations occur all along the life cycle of plastics, starting from the extraction of oil and natural gas as feedstocks of plastic production and including the production of plastic resins at refining and chemical processing facilities, the use of plastics from smaller or limited packaging choices, and management and leakage of plastic waste to the environment (CIEL 2019, UNEP 2021b).
Environmental justice efforts around waste began in the United States with communities (e.g., in Houston, Texas and Warren County, North Carolina) fighting landfills and hazardous waste management facilities in areas populated predominantly by African Americans (Bullard 1990, McGurty 2000). These impacts and concerns continued for years, with
research similar to that done on hazardous waste landfills conducted on U.S. non-hazardous solid waste landfills in the contiguous 48 states finding that these landfills are also more likely to be located in counties with higher percentages of poverty and people of color (Cannon 2020). More recently in Houston and Dallas, Texas, studies show people of color are concentrated in neighborhoods closer to MSW landfill facilities where housing prices and median incomes are lower than those just 2 or 3 miles away (Erogunaiye 2019). This research also showed that the magnitude of disparity within 1–3 miles of a landfill had increased over the 15-year period from 2000 to 2015 (Erogunaiye 2019). Additionally, MSW incinerators are disproportionately located in communities with at least 25% people of color and/or impoverished people (Tishman Environment and Design Center 2019). Burning plastics releases toxic chemical pollutants, such as dioxins and furans (Verma et al. 2016), which can have serious health implications for community members (Tishman Environment and Design Center 2019, Verma et al. 2016, and see Box 1.3 for more information on health impacts).
U.S. EPA, in line with the Biden-Harris Administration’s directive to all federal agencies to “embed equity into their programs and services to ensure the consistent and systematic fair, just, and impartial treatment of all individuals,” announced in April 2021 that it was taking steps to address environmental justice across the agency. These steps include strengthening enforcement of violations, incorporating environmental justice across all its work, improving “early and more frequent engagement with pollution-burdened and underserved communities” and tribal officials, and considering and prioritizing “direct and indirect benefits to underserved communities in the development of requests for grant applications and in making grant award decisions as allowed by law” (U.S. EPA 2021b).
Municipal Solid Waste COVID-19 Impacts
The global COVID-19 pandemic has had extensive impacts on the generation and characterization of MSW in the United States. Within 1 week of various city, state, or national mandates for public areas to use and wear personal protective equipment, such as masks, these items were reported as litter through the Marine Debris Tracker mobile app and to programs of the Ocean Conservancy (Ammendolia et al. 2021, Marine Debris Tracker 2020, Ocean Conservancy 2021). In addition, waste collection companies reported decreases in commercial waste collection because people were not commuting to the office or conducting activities outside of home (Waste Advantage Magazine 2020). For the same reasons, residential waste increased by 5–35%, increasing logistical and economic strain on haulers and communities trying to manage MSW (Dzhanova 2020, Redling 2021).
Other Types of Plastic Waste (Non-MSW)
While some waste categories are included in the measurement of MSW, some other sources of plastic waste are identified below. Only some are measured or monitored under existing federal environmental law. The most consistent and well-documented information on U.S. plastic waste comes from data on management of solid waste under RCRA or documentation of waste recovered from or measured in the environment (see Chapters 4 and 5). Because many leakage estimates rely only on MSW data, they are likely conservative estimates. Aside from the National Oceanic and Atmospheric Administration’s (NOAA’s) Marine Debris Monitoring and Assessment Program (Chapter 6), no federal monitoring programs document or monitor the amount of plastic waste contained in air or water discharges, though state and local governments have conducted specific monitoring studies, sometimes with federal support or assistance.
Construction and Demolition Debris
Starting in 2018, U.S. EPA included construction and demolition debris as a separate section outside of the MSW waste generation in its Sustainable Materials Facts and Figures report (U.S. EPA 2021e). In general, construction and demolition debris materials are durable goods and do not enter the waste stream quickly. However, they are sometimes illegally dumped or managed at unregulated construction sites or abandoned lots and it is unknown what quantity may be entering the ocean.3 Construction and demolition debris is also generated in catastrophic events (e.g., hurricanes, tsunamis, floods, etc.), which can generate debris, including plastics, that enters waterways and the ocean. The most prominent example of this occurred when the Tohoku Tsunami hit Japan. Of the 5 MMT of debris generated, 1.5 MMT floated and portions subsequently were transported to the shores of the United States (Murray, Maximenko, and Lippiatt 2018). It is currently unknown how much plastic waste may enter the ocean in U.S. waters from catastrophic events, such as floods.
Industrial waste is any waste (including plastics) generated by manufacturing or industrial processes. As solid waste, it can be classified under RCRA as either hazardous or non-hazardous solid waste, and governed by assigned management requirements (see Appendix C: Legal Framework for more information). Industrial waste can include plastic pellets, also referred to as nurdles.
3 J. Jambeck, University of Georgia, personal communication, 2021.
Industrial waste can also include sludge and liquid waste from industrial facilities regulated and permitted under other statutes, such as the Clean Water Act (U.S. EPA 2021g); however, the Clean Water Act does not identify plastics as a pollutant for discharge monitoring or limits (Appendix C). However, some chemicals used in plastics (and many other industrial applications) may be separately monitored or regulated. Under the Pollution Prevention Act, which promotes pollution prevention and production, U.S. EPA collects and publicly shares data on industrial facility releases of certain harmful chemicals (including unregulated chemicals) that it lists on the Toxics Release Inventory (TRI) (U.S. EPA 2021i). The TRI does not include plastics but does include several chemicals used in the manufacture of plastics (Wiesinger, Wang, and Hellweg 2021).
Plastic Waste in Wastewater and Stormwater
Some plastic waste enters wastewater infrastructure in sewage, sometimes combined with stormwater. Nearly all large plastic items entering sewers and arriving at wastewater treatment plants are removed by bar screens before treatment through biological and chemical processes. Most microplastics remain in the post-treatment sludge (managed typically through landfilling or land application) with a smaller amount discharged in treated wastewater, mostly as small fibers and fiber fragments (Carr, Liu, and Tesoro 2016). No federally mandated monitoring of plastic waste occurs at wastewater treatment plants. A 2021 U.S. EPA multisector stormwater general permit has been challenged in court for not sufficiently addressing plastic pollution from pre-production plastic pellets, flakes, and powders (Center for Biological Diversity 2021, U.S. EPA 2021g).
Transportation systems are sources of plastic waste in the environment, including plastics shed from the operation of transportation systems (e.g., from tires, paints, brake linings), litter from passengers (considered MSW) and cargo, and litter from transportation systems themselves (e.g., plastics and chemicals from road paint and asphalts). Transportation systems also tend to be sources of plastics to stormwater and other drainage systems that transport plastic wastes to local waterways and as far as the ocean, with tire particles being a major source of microplastics (Werbowski et al. 2021), as described in Chapter 4. Some industrial plastics from transportation systems appear to have special forms of toxicity. For example, a tire-rubber-derived chemical called 6PPD-quinone (also known as (N-(1,3-dimethylbutyl)-N' -phenyl-p-phenylenediamine quinone)) has been identified as a cause of mortality for salmon in the
U.S. Pacific Northwest (Tian et al. 2021). Nonpoint source runoff from highways is subject to management guidance under the U.S. EPA Clean Water Act programs, as well as in coastal and Great Lakes areas through a joint program with NOAA under the Coastal Zone Management Act (U.S. EPA 2021f). However, current federal law does not require monitoring of the sources of macroplastics or microplastics in transportation systems (Appendix C).
The disposal of plastic waste from vessels and at-sea platforms into the ocean is prohibited by the 1988 international maritime regulations (MARPOL Annex V). The United States is a signatory to MARPOL Annex V (an optional, non-mandatory annex of MARPOL), which has been incorporated into U.S. law via the Act to Prevent Pollution from Ships (33 USC § 1901 and 33 CFR Part 151). However, enforcement of MARPOL Annex V is challenging and compliance is difficult to assess. In addition, accidental loss of plastic waste at sea occurs, such as from abandoned vessels, lost ships and cargo, and release of plastic products or plastic “nurdles” from shipping containers. Some of these losses are recognized at the state legislative level, such as abandoned vessels, which are subjects of public concern, but are not well quantified in the United States or U.S. waters.
One type of maritime-generated ocean plastic waste is abandoned, lost, or otherwise discarded fishing gear (ALDFG). No robust estimates of the total amount of ALDFG generated worldwide or by U.S. domestic fisheries are available (Richardson et al. 2021), though a recent global meta-analysis indicates 5–30% of fishing gear is lost annually worldwide depending on gear type (Richardson, Hardesty, and Wilcox 2019). Industrial trawl, purse-seine, and pelagic longline fisheries are estimated to lose a median of 48.4 kt (95% confidence interval: 28.4 to 99.5 kt) of gear each year during normal fishing operations, but this estimate does not include abandoned or discarded gear; other gear known to become derelict such as pots and traps, poles and lines, and driftnets/gillnets; or gear from nearshore and small-scale fisheries (Kuczenski et al. 2022). The role of illegal, unreported, and unregulated fisheries in the generation of ALDFG, or other plastic waste, is also unknown. Lastly, ALDFG resulting from U.S. recreational or subsistence fishing activities is also a source of ocean plastics that is little quantified or understood. There is also growing attention to the contribution of aquaculture activities to plastic waste at a global scale (Sandra et al. 2020), but U.S. contributions have not been assessed. A full description of the types of ALDFG generated in the United States or resulting from U.S.-based fisheries or aquaculture is beyond the scope of this report.
“Managed” plastic waste is contained by treatment and/or conversion into other products (recycling, composting, incineration) or contained in an engineered landfill. If not effectively “managed” in these ways it may have intentionally or unintentionally “leaked” into the environment. Plastic waste not making it into (e.g., illegal dumping, litter) or leaking out of (e.g., blowing litter or unregulated leaking or discharge) our management systems is categorized as “mismanaged” plastic waste. Figure 3.7 represents ways waste may leak, even from a solid waste management system reaching 100% of the population. Once in the environment, wastes are more difficult to recover for later treatment or disposal.
Because U.S. EPA data on MSW does not quantify mismanaged solid waste that leaks into the environment, researchers have developed approaches to derive such estimates, drawing on U.S. EPA-reported data and other data sources. Law et al. (2020) quantified the U.S. contribution of mismanaged plastic waste to the environment as 1.13–2.24 MMT in 2016. Mismanaged waste included a model estimate for litter, illegal dumping, and estimates of exported plastics collected for recycling that were inadequately managed in the importing country. Litter—solid waste that is intentionally or unintentionally disposed of into the environment despite the availability of waste management infrastructure—was coarsely estimated as 2% of plastic solid waste generation (owing to a lack of mass-based estimates of litter rates). For 2016, the quantity of plastic litter estimated annually in the United States was 0.84 MMT (Law et al. 2020). Law et al. (2020) estimated that 0.14–0.41 MMT of plastics were illegally dumped (i.e., disposed of in an unpermitted area) annually,
despite the availability of waste management infrastructure. This estimate comes from assessment of illegal dumping in three U.S. cities (San Jose, California; Sacramento, California; and Columbus, Ohio).
The final component of mismanaged solid waste in the Law et al. (2020) analysis is exported plastic scrap collected for recycling that is inadequately managed in the importing country (see Box 3.1). Law et al. (2020) estimated that in 2016, 0.15–0.99 MMT of plastics exported by the United States in plastic scrap and paper scrap (in which plastics are included as contaminants) bales were disposed of during processing and likely entered the environment in the importing country (Law et al. 2020). The total quantity of plastic solid waste from the United States entering the environment in 2016 was estimated to be 1.13–2.24 MMT. Comparing mismanaged plastic waste from other countries, Law et al. (2020) concluded that the United States was the 3rd to 12th largest contributor of plastic waste into the coastal environment with 0.51–1.45 MMT in 2016.
Similar to the waste management system categorizing the waste stream by material and products, varying plastic products and materials leak from the solid waste management system in different proportions evidenced by what does, and does not, end up in our environment. Litter surveys and community science efforts (at large scales, see Chapter 6) have shown that while plastics make up a large percentage (70–80%, see Table 3.2) of what is found in the environment as litter, the majority of plastic items are single-use, including packaging, as well as tobacco-related (e.g., cigarette filters, product packaging, and e-cigarette cartridges) (Public Health Law Center 2020) and unidentified fragments from larger items. These large-scale surveys generally do not include the documenting of microplastic or pre-production resin pellets at a more local level (Tunnell et al. 2020).
While historically marine litter studies and land-based work have not always been consistent in terms of methods used (Browne et al. 2015), there has been consistent, even if opportunistic, data collection through a few community science-based initiatives. These include the International Coastal Cleanup, which has been collecting data annually for more than 35 years; NOAA’s Marine Debris Monitoring and Assessment Project initiative; and opportunistic data from the mobile app Marine Debris Tracker (initially funded by NOAA) as well as a scientifically designed targeted data collection event in the Mississippi River corridor in 2021 (Youngblood, Finder, and Jambeck 2021). For more information about these programs, please see Chapter 6 on Tracking and Monitoring.
TABLE 3.2 Top 10 Items Tallied from Each Data Set Compilation
|Data Set||Date Range
(n = number of litter items counted)
|Top 10 in Rank Order|
|Ocean Conservancy’s International Coastal Cleanup (USA only)||2015–July 2021
(n = 18,565,446), 82% plastic waste
|Cigarette butts, food wrappers, plastic bottle caps, plastic beverage bottles, straws, stirrers, other trash, beverage cans, plastic grocery bags, glass beverage bottles, metal bottle caps, plastic lids|
|MDMAP Accumulation of items 2.5–30 cm||2009–2021
(n = 895,417), 84% plastic waste
|Hard plastic fragments, foamed plastic fragments, plastic rope/net, bottle/container caps, filmed plastic fragments, plastic other, cigarettes, plastic beverage bottles, food wrappers|
|MDMAP Accumulation of items 30 cm or larger||2009–2021
(n = 5,561), 58% plastic waste
|Lumber/building material, hard plastics, plastic rope/net, other plastics, cloth/fabric, foam plastics, film plastics, other metal, buoys and floats, other processed lumber, plastic bags|
|MDMAP 2.5 cm + standing stock and using MDMAP 2.0 protocol||2009–2021
(n = 71,306), 86% plastic waste
|Hard plastic fragments, foamed plastic fragments, plastic bottle or container caps, plastic fragments film, plastic food wrappers, other plastics, cigarettes, plastic rope or net pieces, processed lumber–building material, plastic beverage bottles, processed lumber–paper and cardboard|
|Marine Debris Tracker (USA only)||2011–July 2021
(n = 2,333,337), 71% plastic waste
|Plastic or foam fragments, cigarettes/cigars, plastic food wrappers, plastic caps or lids, other (trash), plastic bottle, plastic bags, paper and cardboard, aluminum or tin cans, foam or plastic cups or plates, straws|
|Mississippi River Plastic Pollution Initiative (MRPPI)||March 15–April 25, 2021
(n = 75,184), 74% plastic waste
|Cigarette butts, food wrappers, plastic beverage bottles, foam fragments, aluminum cans, hard plastic fragments, plastic bags, plastic/foam cups, paper and cardboard, film fragments.
Note: PPE was 1–2% of all litter found
NOTE: If an item labeled “Other” was in top 10, the 11th ranking item was also included since “Other” can include a wide array of items. MDMAP = Marine Debris Monitoring and Assessment Project, PPE = personal protective equipment.
The Cost of Leakage
While the drivers for leakage of plastics into the environment are complex and varied (see previous section), the cost and burden are borne by communities, especially residents. The United States spends roughly $11.5 billion on cleanup from trash leakage into the environment (Keep America Beautiful Inc. 2010). States, cities, and counties together spend at least $1.3 billion. Cleanup is often a hidden cost within employee salaries or other projects, which makes it difficult to determine the actual cost to local governments. For example, the Georgia Department of Transportation spends more than $10 million on annual labor and equipment costs necessary for picking up and disposing of trash from state roadways (GDOT 2020). CalTrans costs grew from $65 million in 2016–2017 to $102 million in 2018–2019 to keep trash off of transportation areas (CalTrans 2020).
Starting in the 1970s, the United States created several legal frameworks designed to control and prevent the release of harmful, toxic, or hazardous substances, as well as manage transportation, treatment, and disposal of specific wastes. This body of law applies to many materials originally created for societal benefit that were later found to be harmful to human or environmental health, such as polychlorinated biphenyls or chlorofluorocarbons. These U.S. laws address waste disposal and pollution prevention, control, and cleanup across geographic boundaries (by air, water, and soil) by setting science-based criteria and technology-based limits at the federal level, and use command and control or more flexible compliance methods (e.g., cap and trade incentives). Various levels of delegations are shared with state and local authorities. In addition, states may have delegated or parallel requirements.
In 1976, in the wake of a national hazardous waste crisis, Congress fundamentally changed the way solid and hazardous waste is managed in the United States by enacting RCRA.4 RCRA, implemented by U.S. EPA and the states, created a “cradle to grave” solid and hazardous waste management system. This hazardous waste management system prohibited the previous practice of open dumping and replaced it with requirements to use engineered and regulated landfills, composting, and
4 Resource Conservation and Recovery Act (RCRA), Public Law 94-580, October 21, 1976 (42 U.S.C. §§ 6901-6992; 90 Stat. 2795), as amended by P.L. 95-609 (92 Stat. 3081), P.L. 96-463 (94 Stat. 2055), P.L. 96-482 (94 Stat. 2334), P.L. 98-616 (98 Stat. 3224), P.L. 99-339 (100 Stat. 654), P.L. 99-499 (100 Stat. 1696), P.L. 100-556 (102 Stat. 2779).
recovery systems such as recycling.5 RCRA has management requirements assigned to either “solid waste” or “hazardous waste” and currently treats plastic waste as a subset of “municipal solid waste” for disposal in landfills or by incineration.
Other U.S. environmental laws focus on preventing, controlling, and cleaning up discharges of pollutants, hazardous substances, and other contaminants to air and waters (including coastal and marine waters). These include laws enacted to control the discharge of pollutants or hazardous substances from certain facilities into the environment, such as the Clean Water Act, Clean Air Act, Ocean Dumping Act, and the Toxic Substances Control Act. In 1980, Congress assigned liability for cleanup and compensation for injury and contamination from historic contamination by enacting the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, also known as Superfund). All of these laws are implemented by U.S. EPA as the lead agency. U.S. Coast Guard and NOAA have major roles for cleanup, removal, and damage assessment for injury in coastal and marine environments.
Neither the Clean Water Act nor the Clean Air Act controls or measures releases of plastic waste from littering, mismanaged waste, sewage outfalls, runoff, industrial emissions, or other sources. The legal or regulatory definitions of “pollutants” or “hazardous substances” do not include plastics or plastic pollution, though legal challenges are testing whether some may be included based on toxicity or other regulatory criteria. No specific plastic effluent limits for industrial wastewater, stormwater, and plastic production facilities exist unless established under a Clean Water Act regional protocol to protect certain receiving waters from specific discharges, such as from stormwater systems. These include Total Maximum Daily Load (TMDL) limits for “trash” in local water bodies in various locations. While these TMDLs are not specific to plastics, plastic waste is included in trash. The state of California has set plastic discharge limits to govern pre-production plastic discharges.
NOAA plays a leading federal role in plastic waste prevention, removal, cleanup, and restoration through a range of environmental authorities including the Clean Water Act and Ocean Dumping Act, which relates to ship-based disposal. Its most comprehensive role on ocean plastic waste is under the 2006 Marine Debris Research, Prevention, and Reduction Act, amended in 2012, 2018, and 2020 (Marine Debris Act), which specifies its role in cleanup, government coordination, grantmaking, and research. The Marine Debris Act does not provide specific authority for any federal agency to regulate the production, transportation, or release of plastic waste. The most specific legislative action around plastic
5 Code of Federal Regulations (CFR) Title 40, Parts 239–282.
pollution in aquatic and marine environments was the 2015 Microbead Free Waters Act, which prohibits the manufacturing, packaging, and distribution of rinse-off cosmetics and other products, such as toothpaste, that contain plastic microbeads. U.S. EPA operates the non-regulatory Trash Free Waters program, which engages with states and communities on pilot prevention projects.
Most information available on U.S. plastic waste amounts, management, and leakage derives from solid waste data collected by U.S. EPA under RCRA, with other data from NOAA’s Marine Debris Program, import or export data, and some state and local research, cleanup, or pilot projects.
The potential for mismanaged waste starts at the generation of waste (discarded materials), although reused or donated materials are not categorized as waste. With the scale of U.S. waste generation, there is an opportunity to reduce the amount of waste produced, both for the environment as well as the economy, given that all waste management activities take effort, money, energy, and often transportation. As indicated in this chapter, there are multiple paths by which waste can enter into the environment. The next chapters describe how leaked plastic waste travels through the environment and the ocean.
As illustrated throughout this chapter, there are few data sources to understand sources, types, and relative scale of plastic waste generated and disposed or leaked to the environment beyond MSW in the United States. Specifically, there is a lack of plastic waste data on industrial wastes including pre-production plastics and fibers, nonpoint sources of waste such as runoff, point sources, wastewater treatment outflows, and sludge applications.
Furthermore, direct measurements of plastic waste and leakage, in different geographic regions of the United States and urban/rural environments, are necessary to improve and better constrain source estimates from existing crude (order-of-magnitude) model-based estimates, as illustrated in the U.S. EPA data.
Finding 4: The United States is the largest generator of plastic solid waste, by mass and per capita. Plastic product end-of-life disposal
can be improved by enhancing the capability of municipal solid waste systems to collect, sort, and treat specific materials and products, and by considering end-of-life disposal in plastic material and product design and manufacture.
Finding 5: Although recycling is technically possible for some plastics, little plastic waste is recycled in the United States. Barriers to recycling include the wide range of materials (plastic resins plus additives) in the waste stream; increasingly complex products (e.g., multi-layer, multi-material items); the expense of sorting contaminated, single-stream recycling collections; and the low cost of virgin plastics paired with market volatility for reprocessed materials.
Finding 6: Chemical recycling processes that strive toward material circularity, such as depolymerization to monomers, are in early research and development stages. Such processes remain unproven to handle the current plastic waste stream and existing high-production plastics.
Finding 7: Compostable plastics may replace some products currently made with unrecyclable materials. However, successful management of compostable plastics requires widely available managed composting facilities and consumer awareness on product disposal in dedicated compost collection, neither of which exists today.
Conclusion 2: Materials and products could be designed with a demonstrated end-of-life strategy that strives to retain resource value.
Conclusion 3: Effective and accessible solid waste management and infrastructure are fundamental for preventing plastic materials from leaking to the environment and becoming ocean plastic waste. Solid waste collection and management are particularly important for coastal and riparian areas where fugitive plastics have shorter and more direct paths to the ocean.
Conclusion 4: The United States has a need and opportunity to expand and evolve its historically decentralized municipal solid waste management systems, to improve management while ensuring that the system serves communities and regions equitably, efficiently, and economically.
Conclusion 5: Although recycling will likely always be a component of the strategy to manage plastic waste, today’s recycling processes
and infrastructure are grossly insufficient to manage the diversity, complexity, and quantity of plastic waste in the United States.
Recommendation 1: The United States should substantially reduce solid waste generation (absolute and per person) to reduce plastic waste in the environment and the environmental, economic, aesthetic, and health costs of managing waste and litter.